Risk Behavior in Youth Essay Example | Topics and Well Written Essays - 2500 words

Risk Behavior in Youth - Essay Example Most of the established studies on young people in Western societies have been devoted to an understanding of their transition within their families and schools towards adulthood and their working lives. During the different stages of their transition, the young people confront or create risks as they go through. Risk behaviours that include tobacco, alcohol, and drug use are common in young adults, and it is a common finding that those who engage in risky behaviours are prone to engage in additional risky behaviours with passage of time. Social sciences have established that as the number of risky behaviours increase, depression as a comorbidity emerges that take away the productive and fruitful time out of the youth (Viner, R. and Macfarlane, A., 2000). Although not universally true, the young people are prone to take risks sometimes to the extent of a risky life. More recent research in Europe, the UK, the US, and Australia demonstrate a out of bound mismatch between the conventio nal models of transition and the attitudes, choices, and experience of young people themselves in reality. The reason may be significant social and economic changes since the early 1970s. These could have introduced elements of uncertainty, unpredictability and risk into the lives of the young (Young, R., Beinum, MV., Sweeting, H., and West, P., 2007). Thus, it can be stated that risk is a useful concept in understanding young people. In the following sections, evidence for that would be analysed in order to find support for this statement, so some solution can be found to prevent this. Endemicity of Risk There is evidence that risk and uncertainty are certainly endemic, and technology and social institutions are unable to eliminate it. The modern notion of risk is guided largely by uncertainty. Harvest failure, pestilence, migrations, new currents in religion, technological developments, and the unforeseen consequences of urbanization have all exerted a powerful and typically unpredicted influence on the problems and difficulties the population including the young face (Case, S., 2006). Traditionally, lack of certainty in life was attributed to "the other" agencies beyond human control: the ignorance of imperfect humanity, divine agency, luck, destiny, or fate. Many events in the history of society have been the eye openers of the fact that risk has accompanied technical development and revealed the weaknesses of institutions for managing the resulting uncertainty. The social scientific study of people's responses to risk tends to focus on either their narrow cognitive or their broad sociocultural roots (Dworkin, J., 2005). The Young There is a diversity of experiences that characterises the lives of the young people. Although they belong to the same generation they have emerged with different aspirations for the future and have made different choices about their personal interests and priorities, and hence they have different life patterns that do not match with any linear assumption or prediction. Research has shown that young people do indeed possess a sense of persistence and determination in the face of frustrated expectations. After education, every

Introduction and conclusion Essay Example | Topics and Well Written Essays - 500 words

Introduction and conclusion - Essay Example The school is an important place in the life of every student. It is their second home and significant source of knowledge and venue for mastering skills. In this regard, the environment of the school must encourage students to have the zeal for education so as to raise their academic performance. Secondarily, schools are where students spend most of their time each day. Therefore, the facilities of schools should offer a variety of ways to appeal to the learners and leave among them a good impression. The classroom is an important environment where students are exposed to aspects of different fields ranging from basic education to professionalism. Recent research has proven the relationship between performance and classroom facilities. Normally, classroom facilities can either engage or deter students from learning, thus affecting student attendance and academic performance. Tailoring classroom facilities to the developmental needs of students can improve the level of student performance in the classroom. Both the physical and social aspects of classrooms should be considered in order to impact positively on students’ academic performance and social adjustment (Syakima et al., 2011). The basic requirements of a classroom are safety and cleanliness to foster good health and safety. Classrooms should be free from falling objects, well-lighted and well-ventilated. In a report by the U.S. Accounting Office (cited in Schneider, 2002), it was noted that 15,000 schools suffered from poor IAQ, thus affecting health of more than eight million children. The statistics show that a lot of efforts are yet to be done to ensure the safety of school classrooms. However, ventilation and sanitation are only basic requirements in every classroom. The future classroom should have more than the basics. It should respond to the needs of future students. To do so, schools should carefully determine and respond to the needs of students. Some of these

Microsoft Corporation Company Review

Microsoft Corporation Company Review INTRODUCTION Computers have come to be vital technologies in every single line of work at present. Bulk of the present obligations and tasks being completed at assorted firms and associations are by now computer-based, and this is a sure signal that they are keen to invest deeply in these technologies to make their procedures far extra competent and productive. Even if the computer multimedia marketplace is loaded alongside tough competitors, there is no mistrust that Microsoft is method in front of the pack in words of being the most reliable and progressive computer multimedia producing firm all above the world. Its large resources and competent people have allowed the association to produce a expansive array of produce that are able to address the disparate computing needs and hobbies of its globe customers. Microsoft’s attendance all above the globe has additionally come to be stronger above the past couple of years as the firm aims to distinct itself from the rest of the contest and h ave a stable grasp at the top spot of the computer multimedia and hardware industry. With CEO Steve Ballmer grasping the date-to-date procedures of the firm, Microsoft has honestly not ever looked back and has stayed forceful and lucrative even as the present commercial disaster has negatively altered the procedures of its competitors. Specialists forecast that Microsoft will tolerate to solidify its by now dominant locale in the computer multimedia and hardware industry above the subsequent couple of years as they retain on maximising their profitability and comprehensive globe reach. COMPANY BACKGROUND Microsoft Corporation is the leading software company with at least one of its product on virtually every computer on this planet. Bill Gates and Paul Allen founded the company on April 4, 1975. Bill Gates is among the top 3 richest person in this world as declared by Forbes Magazine. Microsoft Corporation deals in developing, licensing designing a range of software products. It also manufactures and sells hardware products. The company has products in entertainment consoles like Xbox360 and Kinect for Xbox. Role of organisational behaviour at the company Microsoft Corporation has a wide range of products under its belt. It is critical for a company of this size to manage its organisational strategies and behaviour to sustain in the market and its position. The company functions in five segments: Windows and Windows Live Division, Server and Tools, Online Services Division Microsoft Business Division. In recent times, Microsoft has given importance to the concept of sustainability. It has initiated an unusual strategy of taxing internal fee on carbon. It will charge its clients for every ton of carbon it produces that means they will charge to recycle every ton of carbon produced. However, it has pointed out a few major reasons this strategy: Behaviour Change – Microsoft aims to reduce the overall carbon emissions and energy utilisation. They have analysed previous reports and emphasised on the use of renewable energy to increase the efficiency. As per the statement by Microsoft’s Chief Environmental Strategist, if someone decides to use carbon based power resources, they’ll be charge an additional fee as a tax to discourage such pathways. Organisation Accountability – Microsoft has learnt from the past to imply new changes to the organisation, it needs to divide it into smaller divisions. The executives that run that facility will be empowered to address any sustainability concerns to drive better efficiency figures and adopt greener power resources. It initiated to tax on carbon power use internally before charging its external clients. Risk Reduction – Microsoft has encouraged all its employees to understand the energy related risks. Microsoft has begun to address its employees and customers to operate through cloud-based services. They utilize significantly their own power and reduce predictable variable cost that brings down the costs and adds to the renewable energy figures. Sales at Vendor Choice – Through its customer feedbacks and previous reports analysis, they have found that the customers are in search of reliable service providers at lower costs and lower carbon emissions. Thus, they have emphasised on alternative energy resources to land new customers and expand their operations with existing clients. (http://blogs.hbr.org/2012/05/microsoft-taxes-itself/) Human Resource Management Human Resource at Microsoft is a priority as the company drives on the path of success based on their employee’s performance. In the beginning, Microsoft used to recruit employee based on their experience over intelligence. But during the slow down of the company’s success, it realised that their employee performance was going down. Bill Gates re-invented the recruitment strategy model by recruiting intelligent staff over experienced staff. According to his experience, he found that intelligence drives aggression in performance. CEO Steve Ballmer says, â€Å"whenever you meet a kick-ass guy, get him† (Bartlett 2). They re-modeled the human resource hiring strategy policies: Attract retain employees, Increase organizational insight, Store and access employee information, Personalize Role Centers to speed productivity Provide online access with employee Portal. Soon, realizing that employee’s are the greatest assets of a company. Microsoft’s strate gies started to reflect this philosophy. The human resource management had the following steps: Recruitment selection, Employee motivation, Employee loyalty satisfaction and Employee rewards. They broke down projects and decided to coherent a strategy of center of excellence to enhance project timing and coordination. Thus, you can measure Microsoft’s success in the recent years based on their employee performance and efficiency. (http://www.microsoft.com/dynamics/en/za/products/ax-hr-management.aspx) (http://mgmt.talkingvillage.com/article.x/1866) International Business Technology Management Microsoft partners with CA Technologies to address its top IT needs. IT companies face fierce competition and challenges like sustainability, IT innovation, management and greener computing. It delivers solutions combine current technology with advanced technology. Technology helps to maximise investments along with security and redundancy to match with the current and future business goals. (http://www.ca.com/us/partners/spotlights/microsoft-corporation.aspx) Analysis of entrepreneurship and innovation at the company Future Strategies Management Adaptive Systems and Interaction: The Adaptive Systems Interaction group (ASI) pursues research on automated reasoning, adaptation, and human-computer interaction. Interests of the group include principles and applications of decision-making and learning, computation in the face of complexity, techniques for information management and search, and the development and evaluation of innovative designs for visualization and interaction. Research goals include both the pursuit of basic science and the development of computing and communications applications that demonstrate new functionalities and flexibility. ASI is at the center of user modelling at Microsoft Research, focused on inferring the goals and needs of users from multiple sources of information about activity and interests. The group is also home to research on information retrieval and management, including work in automated text classification and clustering. The ASI team continually attempts to identify new means for enriching the user experience through advances in automated reasoning and user interface design. (http://research.microsoft.com/en-us/groups/adapt/) Speech technology: Our main aim is to craft requests that make computers obtainable everywhere, and work alongside our product-side partners to make this vision a reality. We are interested not merely in crafting state-of-the-art articulated speech constituents and additionally in how these disparate constituents can come jointly alongside supplementary modes of human-computer contact to form a fused, consistent computing environment. We are pursuing countless undertakings to aid us grasp our vision of a fully speech-enabled computer. (http://research.microsoft.com/en-us/groups/srg/) Natural Language Processing: The aim of the Natural Speech Processing (NLP) group is to design and craft multimedia that will examine, comprehend, and produce tongues that humans use naturally, so that in the end you will be able to address your computer as nevertheless you were addressing one more person. This aim is not facile to reach Understanding speech way, amid supplementary things, knowing what thoughts a word or phrase stands for and knowing how to link those thoughts jointly in a meaningful way. Its ironic that usual speech, the signal arrangement that is easiest for humans to discover and use, is hardest for a computer to master. Long afterward mechanisms have proven capable of inverting colossal matrices alongside speed and grace, they yet flounder to chief the basics of our articulated and composed languages. We address these setbacks employing a blend of knowledge-engineered and statistical/machine-learning methods to disambiguate and answer to usual speech input. Our work has implications for requests like text assessing, data retrieval, question responding, summarization, gaming, and translation. The syntax checkers in Workplace for English, French, German, and Spanish are outgrowths of our research; Encarta uses our knowledge to reclaim answers to user questions; Intellishrink uses usual speech knowledge to compress cellphone messages; Microsoft Product Prop uses our contraption translation multimedia to elucidate the Microsoft Vision Center into supplementary languages. As our work evolves, we anticipate it to enable each span whereas human users can benefit by conversing alongside their computers in a usual way. (http://research.microsoft.com/en-us/groups/nlp/)

michael powell :: essays research papers

(Michael Powell) Federal Communications Commission (FCC) Chairman Michael K. Powell announced last week that he is leaving the powerful independent agency . In his resignation letter to President Bush, Powell said he was stepping down with a "mixture of pride and regret." "Having completed a bold and aggressive agenda, it is time for me to pursue other opportunities and let someone else take the reins of the agency," Powell stated in the letter. "The seeds of our policies are taking firm root in the marketplace and are starting to blossom.(www.Britancica.com) He gave no indication of his future plans other than spending some time with his family. In addition to opportunities in the private sector, Powell has been mentioned as a possible Virginia gubernatorial candidate.Powell was appointed to a Republican seat on the FCC by President Clinton in 1997, only one year after Congress passed the landmark 1996 Telecommunications Act. President Bush selected him as chairman in 2001, replacing Democrat William Kennard. Powell was appointed to a Republican seat on the FCC by President Clinton in 1997, only one year after Congress passed the landmark 1996 Telecommunications Act. President Bush selected him as chairman in 2001, replacing Democrat William Kennard. Powell and the Republican majority that(www. Alwayson-network.com) gained control of the FCC following Bush's 2000 election brought a different and often controversial approach to telecommunications and the Internet. Powell aggressively supported moving voice, video and data transmissions away from the copper legacy networks of the Bells to a variety of minimally regulated broadband platforms. Often accused by consumer groups of serving the Bells' interests, Powell said competition, particularly in the then nascent broadband industry, was better served by multiple platforms providing bundled packages than the Kennard approach to mandating that the Bells provide open access at government-mandated prices to all competitors. The courts repeatedly sided with Powell. "For four years, Chairman Powell fought hard to promote competition and deregulation in key parts of the telecommunications arena," U.S. Rep. Cliff Stearns, a member of the House Subcommittee on Telecommunications and the Internet, said in his statement. "It was a difficult job that often made him a target for criticism, but I believe his leadership on many of these issues will serve the industry and Ameri can consumers very well in the years to come." When Michael Powell assumed the role of chairman on January 22, 2001, there were roughly 130 million wireless subscribers in America. michael powell :: essays research papers (Michael Powell) Federal Communications Commission (FCC) Chairman Michael K. Powell announced last week that he is leaving the powerful independent agency . In his resignation letter to President Bush, Powell said he was stepping down with a "mixture of pride and regret." "Having completed a bold and aggressive agenda, it is time for me to pursue other opportunities and let someone else take the reins of the agency," Powell stated in the letter. "The seeds of our policies are taking firm root in the marketplace and are starting to blossom.(www.Britancica.com) He gave no indication of his future plans other than spending some time with his family. In addition to opportunities in the private sector, Powell has been mentioned as a possible Virginia gubernatorial candidate.Powell was appointed to a Republican seat on the FCC by President Clinton in 1997, only one year after Congress passed the landmark 1996 Telecommunications Act. President Bush selected him as chairman in 2001, replacing Democrat William Kennard. Powell was appointed to a Republican seat on the FCC by President Clinton in 1997, only one year after Congress passed the landmark 1996 Telecommunications Act. President Bush selected him as chairman in 2001, replacing Democrat William Kennard. Powell and the Republican majority that(www. Alwayson-network.com) gained control of the FCC following Bush's 2000 election brought a different and often controversial approach to telecommunications and the Internet. Powell aggressively supported moving voice, video and data transmissions away from the copper legacy networks of the Bells to a variety of minimally regulated broadband platforms. Often accused by consumer groups of serving the Bells' interests, Powell said competition, particularly in the then nascent broadband industry, was better served by multiple platforms providing bundled packages than the Kennard approach to mandating that the Bells provide open access at government-mandated prices to all competitors. The courts repeatedly sided with Powell. "For four years, Chairman Powell fought hard to promote competition and deregulation in key parts of the telecommunications arena," U.S. Rep. Cliff Stearns, a member of the House Subcommittee on Telecommunications and the Internet, said in his statement. "It was a difficult job that often made him a target for criticism, but I believe his leadership on many of these issues will serve the industry and Ameri can consumers very well in the years to come." When Michael Powell assumed the role of chairman on January 22, 2001, there were roughly 130 million wireless subscribers in America.

Notes Eagle Industry With Solutions

Demand Management Volume Leveraging Address factors such standards, requirements, policies reduce related internal demand Aggregate like goods/services across organize,anal units order leverage negro,ate belle pricing terms, condo,ions Source: Cross (2007) 3 procurement decision must consider the Total Cost of Ownership, not just the purchase price. 4 The Formal Strategic Sourcing Process Conduct Opportunity Assessment Profile Us apply Market Develop Issue RFC Negotiate Implement and Manage Performance What buy? From whom? How buy did it oh t? 5 Eagle Industries Case Questions 2. . 4. 5. 6. Why are office products frequently chosen as a lead commodity in strategic sourcing efforts? What observations can you develop about Eagle's SKIS usage, prices they pay and contracts they currently use? Discuss potential implementation barriers. Perform a supplier market analysis and discuss strategic sourcing leverage points you observe. Use information given in the case to estimate potential sav ings. I am looking for specific numbers here. Use the information you assembled thus far to develop a sourcing strategy for Eagle. A. B. C. D. 7.Should they pursue a centralized or decentralized strategy? Should they use contract, catalog, or Internet suppliers? Should they deal with a single supplier or multiple suppliers? How should they structure the contract for Super As, A, B, and C items? What is your recommendation for implementing the strategy? Copyright 2013 Elena Kate, University of 6 Office Products rage Spend: typically $200 – $1 500 per employee. Widely available Many suppliers: potential for competition Implementation barriers often lower/reasonable Administrative purchasing often causes problems.

Everything You Need to Know About Kenya Essay

Kenya is a country in the continent of Africa, on the Indian Ocean coast of East Africa. This country has land on both sides of the equator. This report is going to tell you all about this fascinating country. Jambo (Hello), and we can begin our safari (journey). â€Å"Jambo† and â€Å"safari† are Kiswahili words, one of the languages of Kenya. Kenya is about two times the size of Nevada. It’s slightly smaller than Texas and slightly larger than California, our 2nd and 3rd largest states respectively. The countries that border Kenya are Ethiopia, Sudan, Somalia, Tanzania, and Uganda. Kenya is not landlocked because the Indian Ocean borders Kenya to its right. Kenya is in both the northern and eastern hemispheres. Some major landforms in Kenya include the Kenyan Highlands, Mt. Kenya, the Great Rift Valley, Mau Escarpment, and Mt. Marsabit. The highest elevation is Mount Kenya at 17,057 feet, which is also one of the tallest in Africa. The capital of Kenya is Nairobi. The distance from Nairobi (the capital of Kenya) to Washington D.C. is 7,548 miles. The geography of Kenya supplies some advantages. One area that displays this is the highlands. The highlands provide Kenya with one of the best agricultural regions in Africa. There is rich soil and fertile ground. There is plentiful rainfall and mild climate perfect for farming. High altitude is also great for growing coffee and tea. Kenya is the 4th largest tea producer in the world. Farming provides jobs to the people that live there. Exporting crops such as coffee and tea help provide money in the country. The one and only type of natural vegetation in Kenya is tropical grassland. They have no active volcanoes, but a few centuries ago Mt. Kenya was a volcano. The distance from Nairobi, the capital of Kenya, to the equator is approximately 216 miles. The climate of Kenya is varied. However, overall, the one-month it rains the  most in Kenya is in April when they get 6.3 inches. The average temperature in January is about 68 degrees while in July it’s 63 degrees. The many climates in Kenya include tropical wet, tropical wet and dry, arid, and semiarid. Arid is a dry region and receives approximately 5 inches of rain per year. In the summer Kenya gets .6 inches of rain and in the winter receives .1 inches. The temperature in the summer is 81 degrees Fahrenheit and the winter about 55 degrees Fahrenheit. Semiarid is considered a dry climate type. Summers average 79 degrees Fahrenheit and in the winter averages 51 degrees Fahrenheit. The yearly rainfall is 10 inches in the summer 3.4 and .2 in the winter. Tropical wet and dry is considered a tropical climate. It’s hot all year, averaging 79 degrees all year. It receives about 50 inches of rainfall per year with 10 inches in the summer and .2 inches in the winter. I will now tell you about the history of Kenya before European exploration. Early tribal groups have started to settle in Kenya as far back as 2000 BC. The main reason tribes came here was for the rich, fertile ground, which would be good for farming. Both the highlands and the Rift Valley provided this in southern Kenya. The first migrants to arrive were pastoral nomads from Ethiopia who were in search of fertile ground, which they could use to graze their flocks. They were soon forced to leave and go into central Tanzania because of the climate changes over the centuries and water had begun to be scarce. The Yaaku, or Eastern Cushites, came 1,000 years later and settled in central Kenya. It seems that the Yaaku had been the leader and many more tribes came as the followers and by 100 AD there has been nearly 1,400 pastoral communities in the Rift Valley region. Next, I will tell you about the people of Kenya. The population of Kenya is 31,138,735 people. There are 2,310,000 people living in Nairobi. The population  density is 139 people per square miles in Kenya. Kenya is rural in most  areas, but urban in the capital. The official language of Kenya is English and Kiswahili (Swahili). The major ethnic group of Kenya is Kikuyu, which makes up 22% of the population. The major religion of Kenya is Protestant. 45% of the people follow the Protestant religion. The literacy rate in Kenya is 78.1% overall. Males are 86.3% literate, and women are 70% literate. Many areas lack good education. The life expectancy for women is 48 while the men are expected to life to 46. The population trend is growing greatly at 1.15% per year. One major illness that Kenyans suffer greatly from is HIV/AIDS. I will now tell you about the economy. The major type of economic activity is agriculture including herding and farming. Approximately 75-80% of the working population are in agriculture. It is a primary activity. The main agricultural product is tea. Kenya relies on coffee, tea, and flowers as their limited amount of cash crops. Although they have areas for farming, due to the large population and climate and weather problems, Kenya suffers with both starvation and famine. Some of their leading exports include coffee, tea, and flowers. They have a trade deficit with 3.1 million dollars imported and 1.8 million dollars exported. The major trading partners with Kenya are UK, Tanzania, and Uganda. The major imports Kenya receives are machinery and transportation equipment, petroleum products, motor vehicles, iron and steel, resins, and plastics. The per capita GDP is $1,000 per person. The major natural resource is hydroelectric power. Other natural resources include gold, limestone, s oda ash, salt barites, garnets, and rubies. The currency is called a Kenyan Schilling. A US dollar is worth 77 Kenyan Schillings. I will now tell you about the politics and government of Kenya. The type of government in Kenya is a republic. Recently, the government has not changed. The current leader of Kenya is President Mwal Kibaki. The date Kenya was granted its independence was on December 12th, 1963. The country got its name when Europeans mispronounced the name Kikuyu (what Kenya was then called) for Kenya. The same occurred with the name for Mt. Kenya. There have been no recent civil wars. The ambassador to the US is Yusuf Abdulraham. The name of the major political party is the Forum for the Restoration of Democracy also known as FORD. The international organizations Kenya is a  part of include the UN (The United Nations), IMF (International Monetary Fund), WB (World Bank), OAU (Organization of African Unity), and ISO (International Organization of Standardization). The flag of Kenya has many meanings. The shield represents the pride and tradition of Kenya. The black represents the people. The red represents the blood. Green represents the fertile ground. Finally, the white represents peace. I feel that Kenya is still in the developing stage. Much of the area is rural, with an increasing population, particularly in and around the capital. They have many citizens with HIV AIDS, and have many more suffering from starvation. One strength that Kenya has is that they get 40 inches of rainfall per year. That makes it good for farming, in the areas that they can farm. Another strength is the high altitude and Great Rift Valley that not only allows tea and coffee to grow, but it offers more jobs, which is important with a high population density country like Kenya to have. I think that Kenya will not improve in the future unless they reduce the incidence of Aids and eliminate starvation. Due to limited education, lack of a cure for Aids, and weather conditions that cannot be controlled, the future does not look very promising for Kenya.

Differentiation of bone marrow derived stem cells in articular cartilage repair Essay Example

Differentiation of bone marrow derived stem cells in articular cartilage repair Essay Example Differentiation of bone marrow derived stem cells in articular cartilage repair Essay Differentiation of bone marrow derived stem cells in articular cartilage repair Essay ( Martini et al, 2009 ) with matrix diffusion providing the necessary foods. This means that the ability of gristle to self-repair is highly limited, and harm to articular gristle can bring forth long term complications ( Aigner et al,2003 ) . The limited ego fix abilities of gristle have lead to the development of techniques aimed at cut downing hurting and replacing the damaged gristle. One attack is arthoscopic lavage and debridement which aims to unclutter the articulation of loose gristle that causes mechanical symptoms ( Moseley et al, 1996 ) . While this may supply a impermanent solution to mechanical issues such as locking the symptoms frequently return. It is besides debateable whether the process provides any existent alleviation, as investiagations utilizing placebo operations have found little or no difference between patients having the process and those who underwent a sham-operation ( Moseley et al, 2002 ) . Another technique is microfracture surgery in which the subchondral bone, or the bone beneath the gristle, is drilled exposing marrow-rich blood and bring oning replacing of the damaged articular gristle with a loanblend of hyaline and fibrocartilage, ( Hendrich et al, 2003 ) , ( Steadman et al, 1997 ) . This process has been proven to cut down hurting in a sensible sum of patients, ( Steadman et al, 1997 ) but the gristle produced in chiefly fibrocartilage nto articular gristle. This is non every bit lasting as articular gristle and can intend farther surgery is needed subsequently on in life. The concluding attack requires the organ transplant of osteochondral transplants onto countries of damaged gristle. This normally uses transplants of healthy gristle taken from elsewhere in the joint ( an autoplasty ) and transplants it onto the debauched country ( Werner et al, 2003 ) . This technique replaces the damaged gristle with the hyaline gristle similar to the natural province. This has a sensible success rate in the short term, ( Outerbridge et al, 1995 ) but can take to deformaties in the flexing of the joint. Besides, transplants are sometimes taken from other persons ( an homograft ) , potentially exposing the receiver to infection ( Fox et al, 2002 ) . These attacks have creat ed the possibility of mending articular gristle harm, but are far from perfect schemes with legion complications and frequently necessitating multiple extremely invasive surgeries. However recent probes have created the possibility of cell-based attacks which may an option to the typical processs or gristle fix, really renewing damaged gristle instead than merely replacing it, ( Peterson, 2003 ) . The first cell-based attack used efficaciously is autologous chondrocyte organ transplant or ACT ( Hendrich et al, 2003 ) . In this procedure chondrocytes isolated from little gristle transplants are cultured and injected back onto the site of debasement ( Jobanputra et al, 2001 ) . Consequences of probes into the ACT have been assuring with some demoing about complete regeneration of the gristle ( Roberts et al, 2003 ) . The ability of this attack to renew damaged gristle indicates that cell-based processs could supply the Restoration of normal joint map to persons enduring from articular gristle defects. If chondrocytes can successfully renew harm articular gristle, the following measure in cell-based attacks may be to happen new beginnings of chondrocytes to utilize in gristle fix, and one promising beginning is bone-marrow. Bone marrow contains stems cells called bone marrow root cells or BMSCs, these are normally used by the organic structure for regeneration or fix ( Grove et al, 2004 ) . These cells are made up of both haematopoietic root cells ( HSCs ) and mesenchymal root cells ( MSCs ) . Despite the original location of these cells in bone marrow, they are thought to hold to ability to distinguish into other types of cells under the right conditions ( Orlic et al, 2003 ) . MSCs isolated from bone marrow have been shown in animate being trials to be able to distinguish and graft onto tissues such as myocardium ( Shake et Al, 2002 ) and tendon ( Young et Al, 1998 ) . This indicates that bone marrow derived root cells could supply a method for fix of damaged or diseased tissues, ( Barry, 2003. ) MSCs are of peculiar involvement in gristle fix as they are the primogenitor cells for chondrocytes, which are the cells that make gristle ( Ghadially, 1983 ) . Experimental grounds has shown that bone marrow derived MSCs have besides been able to distinguish into chondrocytes ( Pittenger et al, 1999 ) and appear to make new gristle ( Gun-il et Al, 2001 ; Wakitani et Al, 2001 ) .If these MSCs can be isolated, cultured, and injected they could give rise to hereafter processs used to reconstruct articular gristle. This paper aims to look into non merely the current methods of gristle fix, but to find the degree of cognition on the possible usage of bone marrow derived root cells. This will let opinion on whether or non bone marrow derived MSCs could supply an alternate intervention for articular gristle harm. Section 1 Cartilage, CARTILAGE DAMAGE, AND CURRENT REPAIR TECHNIQUES Cartilage is a connective tissue found in legion countries around the organic structure ( Stockwell, 1979 ) . It is considered to hold belongingss between musculus and bone, being non every bit flexible as musculus but non every bit ridgid as bone ( Marieb et al, 2007 ) . Its belongingss enable it to defy shearing and compaction forces found at countries such as articulated surfaces ( Yuehuei et al, 2003 ) . It is consists of specialized cells called chondrocytes which exist in and assist bring forth an extracellular matrix known as the gristle matrix ( Marieb et al, 2007 ) . Chondrocytes are moderately sparse in the tissue, doing up merely 5 per centum of the matrix s volume ( Yuehuei et al, 2003 ) . The chondrocytes produce both collagen fibers and proteocglycans and combined with the ( Martin et al, 1998 ) high per centum ( up to 80 per centum ) of H2O in the matrix, which helps to give the gristle its compaction resistant belongingss ( Marieb et al, 2007 ) . Cartilage is besides avascular, intending it lacks direct blood supply or lymphatic drainage and therefore relies on the diffusion through this matrix for alimentary exchange ( Stockwell, 1979 ) . The matrix is surrounded by perichondrium which attaches the gristle to environing constructions such as bone and contains the matrix itself ( Martini et al, 2009 ) . There are three chief types of gristle found in the organic structure and are determined by their location and do up. Hyaline gristle is dense in collagen fibers and is the most common ( Martini et al, 2009 ) being found at articulated surfaces of articulations like the articulatio genus ( Martin et al, 1998 ) . Elastic gristle contains elastic fibers and signifiers structural constituents such as the pinnule of the ear ( Martin et al, 1998 ) . The last type is hempen gristle and it besides contains a big figure of collagen fibers. It frequently lies in countries of high compaction such as between the spinal vertebrae ( Martini et al, 2009 ) . Articular gristle is a form hyaline gristle and is found at the jointing surfaces of articulations such as the articulatio genus, frequently on the femoral condyles and the top of the shinbone ( Yuehuei et al, 2003 ) . At these articulations it plays a figure of functions such as daze soaking up, transmittal of forces to cram, and the decrease of clash and rubbing between surfaces ( Ghadially, 1983 ) . It is able to execute these functions because of the alone administration of its assorted fibers and constituents. The basic administration of articular gristle is shown below in figure 1 from ( Martin et al, 1998 ) . The distribution of collagen fibers and proteoglycan is different depending on the distance to the articular surface. There is a higher per centum of collagen fibers at the articular surface and a higher per centum of proteoglycan nearer the bone ( Martin et al, 1998 ) . The collagen fibres near the surface aid defy the tensile emphasis while the proteoglycan deeper in th e matrix helps to cover with compressive forces. The agreement of collagen within the articular gristle is besides different depending on deepness and creates a figure of beds. The lamina splendens contains closely packed thin collagen fibers and helps defy tensile forces and Acts of the Apostless as a barrier to the gristle matrix. The digressive zone contains somewhat thicker collagen fibers and flattened chondrocytes. The transitional zone contains larger still collagen fibers and more chondrocytes ( Martin et al, 1998 ) . The tidemark is the boundary line between the un-calcified and calcified countries of gristle, and helps to defy shearing forces as collagen fibres cross this grade and associate the transitional zone to the calcified gristle ( Martin et al, 1998 ) . Figure 1 Administration of Articular Cartilage Diagram demoing the structural beds of articular gristle ( Martin et al, 1998 ) . Due to the of import function articular gristle plays harm or defects in it can be serious, cut downing motion and quality of life ( Siliski, 1994 ) . The most common types of hurts are due to the unnatural injury such as overloading or emphasis ( Siliski, 1994 ) . These kinds of emphasiss can make gristle lesions which are loosely separated into partial or full thickness lesions ( Hendrich et al, 2003 ) . Partial lesions do non make the subchondral bone and hence do non go through all the manner through the gristle ( Hendrich et al, 2003 ) . They may merely perforate the lamina splendnes or make other countries of gristle such as the transitional zone. Full thickness lesions on the other manus go all the manner through the articular gristle to the subchondral bone ( Hendrich et al, 2003 ) . Both types of lesions damage the gristle matrix ( Siliski, 1994 ) and do an initial inflammatory response. Lesions can besides be more accurately classified depending on the nature of the lesion and its location, and the supposed method of hurt ( Siliski, 1994 ) . An overview of this lesion categorization system is shown in figure 2 below, which uses information from ( Siliski, 1994 ) . Categorization Lesion Type Damage Location Cause Type I Linear Crack Crack of variable deepness in articular surface Weight bearing countries Shearing Forces Type II Stellate Fracture Diverging clefts and flaking at centre Weight bearing countries Direct Trauma Type Three Flap type Flap of basally attached articular gristle Weight bearing countries Pivoting emphasiss Type Four Crater type Full thickness ( to subchondral bone ) Weight bearing countries Numerous breaks and loose organic structures Type V Fibrillation type Fibrillations of gristle surface Lateral, weight bearing country, of Femoral condyle Degenerative arthritis Type VI Degrading type Fraying, soft gristle Weight bearing countries Arthrosis Figure 2 Table of Cartilage harm Classification. Information taken from ( Siliski, 1994 ) . As can be seen in figure 2, there are a figure of different types of gristle runing from the less terrible type I to the serious degrading gristle of type VI. There are besides a broad scope of causes of articular gristle harm from mechanical hurts and diseases, the major disease being Osteoarthritis. Osteoarthritis is a common disease that can do debasement of articular gristle, exposing subchondral bone ( Dickson et al, 2003 ) . It can do intense hurting and decreased mobility, and while it typically affects the aged, early phases can be seen in younger persons ( Buckwalter et al, 1998 ) .The disease has a figure of causes including familial and mechanical causes such as emphasiss and the growing of gristle lesions ( Goldring, 2000 ) . Osteoarthritis causes the break the gristle matrix and cleaving of collagen fibers, this consequences in loss of tensile strength and farther lesion formation ( Goldring, 2000 ) . Overtime the articular gristle is degraded and due to its avascular na ture and the inability of it to self fix, it is non replaced. Therefore the lone method of replacing the debauched gristle and reconstructing full articulation map is through surgical intercession. Current fix techniques rely on non-cell based attacks which fall under three classs, lavage and debridement, microfracturing, and osteochondral grafting. The first technique known as lavage and debridement arthroscopy and aims to unclutter already damaged gristle from a joint. The procedure requires two stairss, the first being lavage where the articulation is washed with fluid and any loose gristle flushed out of the joint ( Moseley et al, 2002 ) . The following phase is the debridement phase in which unsmooth articular gristle is shaved or vacuumed off, farther taking any clogging harm ( Moseley et al, 2002 ) . This debridement forms a smooth skiding surface and allows the articular surfaces to recover most of their orginal map. This process is thought to supply initial alleviation of some symptoms of gristle harm and is frequently the first measure used when gristle harm is less terrible, such as in type I and II harm ( Hendrich et al, 2003 ) . Despite the short term benefits the procedure does non replace the gristle, go forthing the single unfastened to farther degredation. In add-on to this, surveies such as the one performed by B. J. Moseley and co-workers in 2002 suggested that affects of lavage and debridement intervention may be strictly perceived by the patient ( Moseley et al, 2002 ) . Out of 180 patients and equal figure were assigned to lavage, debridement, and a placebo operation. The consequences showed that similar Numberss of patients in the three groups reported decreases in articulatio genus hurting ( Moseley et al, 2002 ) . This raises serious inquiries over the viability of lavage and debridement arthroscopy, and it clearly can non be considered a successful method of handling gristle harm. Another of the chief gristle fix therapies used today is called microfracturing, which relies on the induced incursion of subchondral bone to created replacing gristle on the articular surface ( Steadman et al 1997 ) . Multiple holes are drilled into the subchondral bone to the bone marrow ; this causes blood rich in marrow contents to coagulate in the countries environing the holes. Mesenchymal primogenitor cells from the marrow rich blood are so thought to make new chondrocytes which replace the damaged gristle ( Hendrich et al, 2003 ) . This method provides a longer-term solution than lavage and debridement, as consequences surveies such as a 1997 survey by Steadman et al show. In this survey 75 % of patients reported decreased articulatio genus hurting between 3 and 5 old ages after intervention ( Steadman et al 1997 ) . However the gristle produced chiefly fibrocartilage ( Kreuz et al, 2006 ) which is non every bit lasting as natural articular gristle and finally degrades under the conditions in articular articulations ( Kreuz et al, 2006 ) . The process may besides make complications in the motion of articulations following boring of the bone. These complications may include unnatural flexing and agreement under tonss or lockup of the joint ( Steadman et al 1997 ) . The concluding process in common usage is osteochondral grafting. This techniques uses transplants of healthy articular gristle and grafts them on the countries of harm or degredation. Grafts may come from less to a great extent loaded countries of the joint ( an autologous transplant ) ( Schenettler et al, 2008 ) , or may be a gristle transplant from another person ( an homograft ) . Holes are drilled in the country of subchondral bone under the debauched gristle and transplant of healthy tissue is pressed into it, covering the damaged country. This is a technique is utile because it replaces the damaged gristle with the same hyaline gristle that would be found at that place of course, and this has proven to be effectual over the long term in a sensible sum of patients ( Schenettler et al, 2008 ) . However the process besides comes with a figure of serious complications such as transmittal of infection during the usage of homografts ( Fox et al, 2002 ) . Additionally, the transplant may neglect to attach decently with both the surrounding gristle and the subchondral bone, or the transplant itself can interrupt up taking to what is known as graft failure ( Fox et al, 2002 ) . The interruption up or relaxation of the transplant can make loose organic structures inside the joint and lead to greater limitation of joint motion. Section 2 -DIFFERENTIATION OF BONE MARROW DERVIED STEM CELLS AND POTENTIAL FOR REPAIR Bone marrow is a squashy tissue found inside castanetss and can be divided into xanthous bone marrow and ruddy bone marrow ( Matini et al, 2009 ) . The chief maps of bone marrow are to bring forth new blood cells and to renew damaged tissue found in the organic structure ( Kauser et al, 2007 ) . The ability of bone marrow to renew damaged tissue is due to cells found in bone marrow called bone marrow root cells ( BMSCs ) , which consist of hematopoietic root cells ( HSCs ) and mesenchymal root cells ( MSCs ) ( Grove et al, 2004 ) . HSCs were foremost discovered in 1970 ( Kauser et al, 2007 ) , and act as the primogenitor cells for blood cells such as ruddy blood cells and myeloid cells like as macrophages and neutrophils ( Sherwood, 2010 ) . MSCs do non give rise to blood cell line of descents but have been shown to distinguish into a scope of connective tissue cell types like apidocytes, chondrocytes, and bone-forming cells ( Grove et al, 2004 ) . The ability of BMSCs to distinguish and give rise to different cell types may hold opened the possibility of new interventions for tissue fix around the organic structure ( Grove et al, 2004 ) . Tissues that could potentially be repaired and regenerated by BMSCs include skeletal musculus, cardiac musculus, and even tissue in the cardinal nervous system. Muscle growing and harm is controlled stem-cells called orbiter cells, which are merely found in musculus ( Campion, 1984 ) . These cells act as the primogenitor cells for myofibres which make up the musculus construction and can be localised to countries of harm or debasement. BMSCs may be able to give rise to skeletal musculus cells in a similar manner to the orbiter cells and therefore may be able to assist renew musculus fibers ( Ferrari et al, 1997 ) . Evidence of this can be seen in a 1997 probe by G. Ferrari and co-workers, who used transgenic mice to find the consequences of shooting uniform BMSCs into damaged musculus. The mice, which expressed a particular marker B-Galactosidase cistron, received injections of BMSCs into the tibialis anterior musculus which had antecedently damaged ( Ferrari et al, 1997 ; Grove et Al, 2004 ) . After a clip period of 2-5 hebdomads the repaired musculus was inspected and was found to incorporate musculus fibers showing the marker cistron. Thi s indicated that musculus fibers had differentiated from the injected BMSCs, proposing that BMSCs could play a function in musculus fix ( Ferrari et al, 1997 ) . However, when compared to a control group of mice that were injected with satellite cells it was found that the orbiter cells were incorporated into the musculus at a much higher rate ( Ferrari et al, 1997 ; Grove et Al, 2004 ) , which inquiries the virtue of utilizing BMSCs over extracted orbiter cells. In add-on to this farther survey has suggested the distinction of BMSCs into skeletal musculus may be due to merger of the BMSCs with bing musculus ( Ye et al, 2003 ; Grove et Al, 2004 ) , intending the ability of BMSCs to mend skeletal musculus may hold been overstated. The ability of BMSCs to distinguish into cardiac musculus has besides been investigated, with the purpose of happening cell-based therapies for cardiac musculus harm caused by myocardial infarction and other upsets ( Orlic et al, 2003 ; Grove et Al, 2004 ) . Work by Tomita S. Et Al in 1999 showed that BMSCs can organize cardiac-like cells and potentially better bosom map ( Tomita et al, 1999 ) . In this survey chemicals were used to bring on distinction of troponin marked BMSCs into myogenic cells, and these were injected onto damaged cardiac tissue. The cells formed cardiac-like cells and even linked together and formed myotubules ( Tomita et al, 1999 ) , demoing high degrees of distinction. Not merely did these cells successfully integrate into the damaged myocardium, but they besides showed an betterment in bosom map with additions seen in peak systolic force per unit area and ventricular volume ( Tomita et al, 1999 ) . This probe was really successful in turn outing the potency o f BMSCs in cardiac fix and regeneration, and in the writer s sentiment should be considered as an alternate graft cell to mend damaged myocardium , ( Tomita et al, 1999 ) . In add-on to simple musculus harm BMSCs are thought to be able to distinguish into other tissues and cells such as those found in the cardinal nervous system or CNS. This is peculiarly utile because CNS tissue is normally non-renewable and hard to mend, and replacing of losing cells appears to be the lone manner to handle harm ( Grove et al, 2004 ; Gage et Al, 2000 ) . Glial cells of the CNS are thought to be dervied from BMSCs in the human organic structure ( Eglitis et al, 1997 ) , which suggests the potency of BMSCs to be used to replace losing or damaged cells. A survey done in 2000 by Sanchez et Al, showed that BMSCs can be differentiated into nervous cells under certain conditions ( Sanchez et al, 2000 ) . In the survey, BMSCs were isolated and cultured with extracted nervous root cells and a differentiation medium incorporating neural growing factors, in order to bring on distinction. A figure of the BMSCs successful differentiated into cells showing the neural marker NeuN, a nd although probes into the potency of BMSC to CNS distinction are ongoing, suggests that BMSCs have the possible to be used in replacing therapies for CNS harm or debasement ( Sanchez et al, 2000 ) . Section 3 CELL-BASED THERAPIES AND BONE MARROW STEM CELLS IN THE REPAIR OF ARTICULAR CARTILAGE As mentioned before, articular gristle is really hard to reapair, chiefly due to its avascular nature ( Martini et al, 2009 ) . The current interventions for articular gristle harm are successful to a certain grade, particularly in the short term, but come with legion complications and frequently fail to reproduce gristle of a similar construction and strength ( Hendrich et al, 2003 ) . Cell-based attacks utilizing the abilities of BMSCs may supply a more successful method of intervention. One of the first cell-based therapies developed is autologous chondryocyte organ transplant or ACT, which uses cultured chondrocytes to renew harm gristle ( Peterson, 2003 ) . In this procedure a subdivision of gristle is removed and the chondrocytes cultured for a clip period of 2 to 3 hebdomads ( Bittenberg et al, 1994 ) , and so injected back into the damaged articulation with a flap of periosteal to incorporate them. One of the earliest probes into ACT was performed by Bittenberg et Al in 1994, on full thickness defects of the articulatio genus ( Bittenberg et al, 1994 ) . Of the patients who underwent the surgery, 100 % reported short term hurting alleviation and increased motion ( Bittenberg et al, 1994 ) . The consequences after a long term period of 2 old ages were besides assuring, with 14 out of 16 patients with old harm to fermoral chondylar harm demoing distinguishable betterment and coverage less hurting. In add-on to the patient feedback reviews of the grafts showed tha t they had integrated with the environing gristle and showed similar belongingss to natural articular gristle ( Bittenberg et al, 1994 ) . Despite the little figure of complications such as transplant wear doing hurting, this probe showed that ACT is a successful method of fix and the process has been in common usage since 1987 ( Peterson, 2003 ) . The success of this process is visualised in figure 3 below which shows the same subdivision of gristle before and after ACT. The repaired gristle can be seen in the after exposure on the right, demoing complete integrating into environing gristle. However, even though ACT shows promising consequences and is now a normally performed process, it still requires the remotion of gristle from the joint to bring forth chondrocytes for organ transplant ( Peterson, 2003 ) , this may go forth other countries of the joint without equal gristle and is really invasive. Due to the find of the malleability of BMSCs and their ability to distinguish into chondrocytes ( Pittenger et al, 1999 ) , it may be possible to make condrocytes from stray bone marrow civilizations. Chondrogenic distinction of bone marrow derived MSCs was investiaged by Johnstone B. et Al in 1998, in which MSCs were isolated and induced to undergo chondrogenesis in a cell sum. After approximately 5 yearss in civilization, the visual aspect of collagen II fibres, similar to that produced by chondrocytes was noted ( Johnstone et al, 1998 ) . When examined, the cell aggregates besides contained proteoglycans of a similar nature to those produced by chondrocytes, which suggested that chondrogenic distinction had occurred in the civilized bone marrow derived MSCs ( Johnstone et al, 1998 ) . These consequences were supported by work done by Mackay A. M. et Al in 1998, who attempted to bring on chondrogenesis in MSCs utilizing Decadron and transforming growing factors ( Mackay et al, 1998 ) . The survey besides found grounds of collagen II and proteoglycan production and besides noted the formation of an extracellular matrix similar to that found in natural articular gristle ( Mackay e t al, 1998 ) . Although the ability of MSCs to give rise to chondrocytes is interesting, for it to hold a clinical impact on countries such as gristle fix, methods must be made to present the differentiated MSCs to the country of damaged gristle. Such a method may hold been devised utilizing distinguishing MSCs into chondrocytes on a biodegradable polymer concept ( Tuan, 2003 ) . In this method the concept is press-coated into a civilization of stray MSCs which were so induced into chondrogenic distinction utilizing Decadron and grow factors. After chondrogenic distinction, chondrocyte-like cells coat the concept and even get down to bring forth a cartilage-like extracellular matrix, dwelling of collagen fiber and proteoglycans ( Tuan, 2003 ) . The gristle covered concept can so be transplanted onto an country of gristle harm or debasement, where it could incorporate with the remainder of the gristle and renewing new articular gristle. Other scaffold-like constructions have besides been developed s uch as three-dimensional amalgam scaffolds and nanofibrous scaffolds ( Tuan, 2003 ; Li et Al, 2005 ) , which rely on similar methods but require the chondrogenic cells to be seeded onto them alternatively of the press-coating method mentioned before. While the potency of these scaffold based methods is good, probes on really patients are still in the early phases and consequences are ill-defined. Discussion The ability of BMSCs to distinguish into a broad assortment of non-hematopoietic tissues provides the potency for new interventions of diseases and harm in skeletal musculus, cardiac musculus and in the CNS ( Ferrari et al, 1997 ; Orlic et Al, 2003 ; Sanchez et Al, 2000 ) . However it is the ability of BMSCs to distinguish into chondrocytes which is possibly the most interesting in a clinical sense due to the limited ego fix of gristle and the big sum of people affected by disease such as degenerative arthritis ( Dickson et al, 2003 ) . Yet despite the comparative successes of probes into MSCs to chondrocyte distinction, inquiries are still being raised over how effectual the can be and the viability of these cells in intervention of gristle harm. The first job is the success of chondrogenic distinction, which although possible, can happen at changing rates in different surveies. In the 1998 survey by Johnstone et Al, grounds suggested that stray MSCs had been successfully differentiated into chondrocyte-like cells and could reproduce a similar extracellular matrix as seen in gristle. However, the sum of cells that differentiated was widely variable as was the production of collagen fibers and the extracellular matrix ( Johnstone et al, 1998 ) . Variation was besides seen in the morphology of the cells as the forms changed depending on concentration of growing factors. While much of the difference in size, figure and form was attributed to different concentrations of growing factors ( Johnstone et al, 1998 ) . , the variableness of the consequences suggests that, despite grounds of successful chondrogenesis, the process used to bring on chondrogenesis demands to be farther developed to make consistent chondrogenic cells. The existent ability of BMSCs to distinguish may besides be overstated as surveies have suggested that a phenomenon known as cell merger may make the semblance of cells being more pluripotent ( Ye et al, 2003 ; Grove et Al, 2004 ) . This was investigated in paper by Wang X. et Al in 2003, which investigated bone marrow derived hepatocytes whether or non they could be formed by bone marrow HSCs. Despite the successful creative activity of hepatocytes the findings suggested that they arise from the HSCs undergoing cell merger ( Wang et al, 2003 ) . Another illustration of this was seen in a 2002 probe done by Terada N. Et Al, which suggested BMSCs merely follow the phenotype of certain cells and that cistrons of giver cells could easy be misinterpreted as cistrons of differentiated cells, giving the visual aspect of trans-differentiation when there was none ( Terada et al, 2002 ) . Further inquiries about the malleability of BMSCs have been raised by probes that suggest BMSCs do non di stinguish into certain tissue types. For illustration, a survey done by Castro R. F. Et Al, failed to observe a B-galactosidase marker in cells they thought would distinguish into nervous root cells, bespeaking that BMSCs could non give rise to nervous cells ( Castro et al, 2002 ) . Assuming that the root cells found in bone marrow can distinguish into cells of different tissues such as gristle, the inquiry has to be asked whether or non bone marrow is the best beginning these root cells. Mesenchymal root cells, which are thought to give rise to chondrocytes under the right conditions ( Grove et al, 2004 ) , are besides found in tissue such as adipose tissue ( Zuk et al, 2001 ) . The advantages of utilizing adipose tissue include the big measures, minimum uncomfortableness, and less invasive nature necessitating far simpler and less complicated surgeries ( Zuk et al,

Free Essays on Truth And The Rules Of Attraction

The book The Rules of Attraction, by Bret Easton Ellis, is a book that delves into the lives and personalities of young college students. It exposes the startling truth about the way point of view can skew a story. The story jumps around, retelling the same scene, each time narrated by another character. Although each explanation of the characters’ encounters with each other was factually correct to that individual, the stories conflicted. By giving contradictory stories and paradoxical truths, Ellis questions the reader as to what truth really is and whether it exists. Ellis’s use of the rotating first person was very intriguing and thought provoking, as it considers the reality of truth. This book essentially revolved around Sean, Paul, and Lauren. Sean entered the book as a disgruntled realist frustrated with his environment. He was an apathetic lost soul on campus who rarely cared about others. Enjoying his binge-drinking and habitual drug use, he viewed Camden as a college where he had no place. Soon the object of Paul’s affection, he did not describe their relationship to be anything of the romantic nature. He regarded Paul as only an annoying acquaintance, and often did not even extend friendship to him. Paul, an openly bisexual tramp, had innumerable sexual encounters with most the men and women of Camden College. His melodramatic personality often masked the truth by his embellished take on the world. He met Sean and allegedly had a sexual encounter with him that started a romantic relationship between them, although Sean never confirmed their affair. Meanwhile, Sean had slowly become infatuated with Lauren, a girl who was very indecisive with her life. She indulged in alcohol and drugs, just as everyone else on her campus did. She and Sean had a very dysfunctional relationship, one in which the line between love and hate was often blurred. After Sean slept with Lauren’s best friend Judy, Lauren parte... Free Essays on Truth And The Rules Of Attraction Free Essays on Truth And The Rules Of Attraction The book The Rules of Attraction, by Bret Easton Ellis, is a book that delves into the lives and personalities of young college students. It exposes the startling truth about the way point of view can skew a story. The story jumps around, retelling the same scene, each time narrated by another character. Although each explanation of the characters’ encounters with each other was factually correct to that individual, the stories conflicted. By giving contradictory stories and paradoxical truths, Ellis questions the reader as to what truth really is and whether it exists. Ellis’s use of the rotating first person was very intriguing and thought provoking, as it considers the reality of truth. This book essentially revolved around Sean, Paul, and Lauren. Sean entered the book as a disgruntled realist frustrated with his environment. He was an apathetic lost soul on campus who rarely cared about others. Enjoying his binge-drinking and habitual drug use, he viewed Camden as a college where he had no place. Soon the object of Paul’s affection, he did not describe their relationship to be anything of the romantic nature. He regarded Paul as only an annoying acquaintance, and often did not even extend friendship to him. Paul, an openly bisexual tramp, had innumerable sexual encounters with most the men and women of Camden College. His melodramatic personality often masked the truth by his embellished take on the world. He met Sean and allegedly had a sexual encounter with him that started a romantic relationship between them, although Sean never confirmed their affair. Meanwhile, Sean had slowly become infatuated with Lauren, a girl who was very indecisive with her life. She indulged in alcohol and drugs, just as everyone else on her campus did. She and Sean had a very dysfunctional relationship, one in which the line between love and hate was often blurred. After Sean slept with Lauren’s best friend Judy, Lauren parte...

Biology Aqa

16. 8 – Genetic fingerprinting43 Section 9. 1 – Sensory Reception †¢ A stimulus is a detectable change in the internal or external environment of an organism that produces a response. The ability to respond to a stimulus increases an organism’s chances of survival. †¢ Receptors transfer the energy of a stimulus into a form that can be processed by the organism and leads to a response. †¢ The response is carried out by â€Å"effectors† which can include cells, tissues, organs and systems. Taxis – A simple response that’s direction is determined by the direction of the stimulus An organism can respond directly to a change in the environment by moving its body either: 1. Toward the stimulus (positive taxis) 2. Away from the stimulus (negative taxis) Kinesis – Results in an increase of random movements †¢ Organism does not move towards/away from the stimulus †¢ The more intense the stimulus the more rapid the movements †¢ Kinesis is important when the stimulus is less directional such as heat or humidity Tropism – a growth movement of part of a plant in response to a directional stimulus Positive phototropism – shoots/leaves Positive Geotropism – roots Section 9. 2 – Nervous Control Nervous organisation The nervous system can be thought of as having two main divisions: . The central nervous system (CNS) – brain and spinal cord 2. The peripheral nervous system (PNS) – Made up of pairs of nerves that originate either from the brain or the spinal cord The peripheral nervous system This is divided into: †¢ Sensory neurons which carry impulses away from receptors to the CNS †¢ Motor neurons which carry nervous impulses from the CNS to effectors The spinal cord is a column of nervous tissue A reflex – involuntary response to a stimulus (you do stop to consider an alternative) The pathway of neurons involved in a reflex is called a reflex arc. Reflex arcs contain just 3 neurons: 1. A sensory neuron 2. An intermediate neuron 3. A motor neuron There are several stages of a reflex arc: 1. Stimulus 2. Receptor 3. Sensory neuron 4. Synapse 5. Coordinator (intermediate neuron) 6. Synapse 7. Motor neuron 8. Effecter 9. Response Importance of the reflex arc †¢ Involuntary – does not require the decision making power of the brains †¢ Brain can override the response if necessary †¢ Protects the body from harmful stimuli Effective from birth – does not need to be learnt †¢ Short pathway – fewer synapses Synapses – slow Neurons – fast Section 9. 3 – Control of heart rate The Autonomic nervous system Controls subconscious activities of muscles and glands Has two main divisions: The sympathetic nervous system – Speeds up activities and thus allows us to cope with stressful situations (fight or flight r esponse) The parasympathetic nervous system – Inhibits effects and slows down activities. This allows energy to be conserved. Controls under normal resting conditions The two divisions are antagonistic meaning that their effects oppose one another Control of heart rate Changes of the heart rate are controlled by a region of the brain called the medulla oblongata which has two main divisions One division is connected to the sinoatrial node through the sympathetic nervous system The other is connected to the sinoatrial node via the parasympathetic nervous system Control by chemoreceptors Chemoreceptors are found in the wall of the carotid arteries and detect hanges in pH as a result of CO2 concentration When CO2 concentration in the blood is too low, chemoreceptors detect the drop in pH and send impulses to the section of the medulla oblongata responsible for increasing heart rate This section then increases the number of impulses sent to the S. A node via the sympathetic nervous system This results in an increase in heart rate which then causes blood pH to return to normal. Control by pressure receptors Pressure receptors occur in the wall of the carotid arteries and the aorta When blood pressure is too high – impulses are sent to the medulla oblongata which then sends impulses to the S. A node via the parasympathetic nervous system decreasing the heart rate When blood pressure is too low – impulses are sent to the medulla oblongata which then sends impulses to the S. A node via the sympathetic nervous system, increasing the heart rate Section 9. 4 – Role of receptors Features of sensory reception A sensory receptor will: †¢ Only respond to a specific type of stimulus (e. g. light, pressure, etc) †¢ Produce a generator potential by acting as a transducer. This means that it can convert the information to a form that the human body can interpret. This is achieved by using the energy of a stimulus into a nerve impulse called a generator potential. Structure and function of a pacinian corpuscle Responds to mechanical pressure Occurs in ligaments and joints so that it is possible to tell which direction a joint is changing The neuron of a pacinian corpuscle is in the centre of layers of tissue, each separated by gel The sensory neuron of a pacinian corpuscle has stretch-mediated sodium channels in its plasma membrane †¢ During its resting state, stretch-mediated sodium channels are too narrow to allow sodium through. The corpuscle therefore has a resting potential †¢ When pressure is applied, the membrane of the neuron is stretched causing sodium channels to widen therefore allowing sodium to diffuse into the neuron †¢ The influx of sodium ions cause a change in the polarity of the neuron, creating a resting potential †¢ The generator potential creates a action potential which moves along the neuron Receptors working together in the eye Different receptors respond to a different intensity of a stimulus Light receptors of the eye are found in the retina (the inner most layer) The light receptors in the eye can are of two types, rod and cone cells. Both receptors convert light energy into a nervous impulse and are therefore acting as transducers Rod cells Cannot distinguish between different wavelengths Many rod cells are connected to the same neuron and so can function at low light intensities. A threshold must be reached in the bipolar cells to which they are attached to and so since they can all contribute to reaching this threshold, they will function at lower light intensities Rod cells breakdown the pigment rhodopsin to generate an action potential. Rhodopsin is easily broken down in low light intensity Since more that one rod cell is connected to the same neuron, only one impulse will be generated. It is impossible for the brain to determine which rod cells were stimulate to begin with and so it is not possible to determine exactly the source of light This results in rod cells having a relatively poor visual acuity and so are not very effective in distinguishing between two points close together Cone cells There are three types of cone cells, each of which respond to a different avelength The colour interpreted depends of the proportion of each type of cone cell stimulated Cone cells are connected only to one bipolar cells, this means that they cannot combine to reach a threshold. As a result of this a high light intensity is required to create a generator potential Cone cells breakdown the pigment iodopsin to create a generator potential Iodopsin can only be broken down by a high light intensity Since cone cells are connected to a single bipolar cell, when two adjacent cells are stimulated, two separate nervous impulses will be sent to the brain. This means that it is easier to determine the source of the light. As a result, cone cells are responsible for higher visual acuity since they allow you to better distinguish between two points Light is concentrated by a lens to the centre of the eye called the fovea. This region receives a high light intensity and therefore has more cone cells. The peripheries of the eye receive a low light intensity and therefore consist mainly of rod cells. Section 10. 1 – Coordination Body systems cannot work in isolation and must therefore be integrated in a coordinated fashion. Principles of coordination In mammals, there are two main forms of coordination: 1. The nervous system – Uses nerve cells that can pass electrical impulses along their length. The result is the secretion of chemicals by the target cells called neurotransmitters. The response is quick, yet short lived and only acts on a localised region of the body. 2. The hormonal system – Chemicals are transported in the blood plasma which then reach target certain cells, thus stimulating them to carry out a function. The responses due to secretion of hormones often act over a longer period of time, yet are slower to act. Chemical mediators Nervous and hormonal forms of communication are only useful at coordinating the activities of the whole organism. At the cellular level they are complimented by chemical mediators. Chemical mediators are secreted by individual cells and affect other cells in the immediate vicinity. A common example of this type of coordination is the inflammation of certain tissues when they are damaged or exposed to foreign agents. Two examples of chemical mediators are: 1. Histamine – Stored in white blood cells and is secreted due to the presence of antigens. Histamine causes dilation of blood vessels, increased permeability of capillaries and therefore swelling the infected area. 2. Prostaglandins – Found in cell membranes and cause dilation of small arteries and arterioles. They release due to injuries and increase the permeability of capillaries. They also affect blood pressure and neurotransmitters. In doing so they relieve pain. Hormonal system |Nervous system | |Communication by chemicals |Communication by nervous impulses | Transmission takes place in the blood |Transmission is by neurons | |Transmission is generally slow |Transmission is very rapid | |Hormones travel to all areas of the body, but target only |Nerve impulses travel to specific areas of the body | |certain tissues/organs | | |Response is widespread |Response is localised | |Effect may be permanent/long lasting/ irreversible |Effect is temporary and reversible | Plant growth factors Plants respond to external stimuli by means of plant growth factors (plant hormones) Plant growth factors: †¢ Exert their influence by affecting growth †¢ Are not produced by a particular organ, but are instead produced by all cells †¢ affect the tissues that actually produce them, rather than other tissues in a different area of the plant. One plant hormone called indoleacetic acid (IAA) causes plant cells to elongate Control of tropisms by IAA IAA is used to ensure that plant shoots grow towards a light source. 1. Cells in the tip of the shoot produce IAA, which is then transported down the shoot. 2. The IAA is initial transported to all sides as it begins to move down the shoot 3. Light causes the movement of IAA from the light side to the shaded side of the shoot. 4. A greater concentration of IAA builds up on the shaded side of the shoot 5. The cells on the shaded side elongate more due to the higher concentration of IAA 6. The shaded side of the root therefore grows faster, causing the shoot to bend towards the source of light IAA can also effect the bending of roots towards gravity. However in this case it slows down growth rather than speeds it up. IAA decreases root growth and increases shoot growth Section 10. 2 – Neurons Specialised cells adapted to rapidly carry electrochemical changes (nerve impulses) from part of the body to another Neuron structure Cell body †¢ Nucleus †¢ Large amounts of rough endoplasmic reticulum to produce neurotransmitters Dendrons †¢ Extensions of the cell body sub-divided into dendrites †¢ Carry nervous impulses to the cell body Axon †¢ A single long fibre that carries nerve impulses away from the cell body Schwann cell †¢ Surrounds the axon †¢ Protection/electrical insulation/phagocytosis. Can remove cell debris and are associated with nerve regeneration. Myelin sheath †¢ Made up from the Schwann membrane which produces myelin (a lipid) †¢ Some neurons are unmyelinated and carry slower nerve impulses Nodes of Ranvier †¢ The gaps between myelinated areas †¢ 2 – 3 micrometers long and occur every 1 – 3mm Sensory Neuron †¢ Transmit impulses from a receptor to an intermediate neuron or motor neuron †¢ One Dendron towards the cell body, one axon away from the cell body Motor neuron †¢ Transmit impulses from the sensory/intermediate neuron to an effector †¢ Long axon, many short dendrites Intermediate neuron †¢ Transmit impulses between neurons †¢ Numerous short processes Section 10. 3 – The nerve impulse A nerve impulse is not an electrical current! It is a self-propagating wave of electrical disturbance that travels along the surface of an axon membrane. Nerve impulse – temporary reversal of the electrical p. d across an axon membrane The reversal is between two states The resting potential no nerve impulse transmitted The action potential – nerve impulse transmitted Resting potential †¢ Sodium/potassium are not lipid soluble and cannot cross the plasma membrane. Transported via intrinsic proteins – ion channels †¢ Some intrinsic proteins actively transport potassium ions into the axon and sodium ions out. This is called the sodium potassium pump. Sodium potassium pump 3 sodium ions pumped out for every 2 potassium ions pump in †¢ Most gated potassium channels remain open – potassium ions move out of the axon down their chemical gradient †¢ Most gated sodium channels remain closed The action potential †¢ Temporary reversal of the charge of the membrane from (-65mV to +65mV). When the p. d is +65mV the axon is said to be depolarised †¢ Occurs because the ion channels open/close depending upon the voltage across the membrane †¢ When the generator potential is reached, sodium ion channels open and potassium close, allowing sodium to flood into the axon. Sodium being positively charged causes the axon to become more positive in charge The passage of an action potential along an unmyelinated axon †¢ Stimulus – some voltage – gated ion channels open, sodium ions move in down electrochemical gradient †¢ Causes more sodium channels to open †¢ When the action potential reaches ~ +40mV sodium channels close †¢ Voltage – gated potassium channels open and begin repolarisation of the axon Hyper – polarisation †¢ The inside of the axon becomes more negative than usual due to an â€Å"overshoot† in potassium ions moving out of the axon. †¢ Potassium channels close †¢ Sodium potassium pump re-established the -65mV resting potential Section 10. 5 – The speed of a nerve impulse Factors affecting speed 1. The myelin sheath – Prevents the action potential forming in myelinated areas of the axon. The action potential jumps from one node of Ranvier to another (salutatory conduction) – this increases the speed of the impulse as less action potentials need to occur 2. The greater the diameter of the axon the greater the speed of conductance – due to less leakage of ions from the axon 3. Temperature – Higher temperature, faster nerve impulse. Energy for active transport comes from respiration. Respiration like the sodium potassium pump is controlled by enzymes. Refractory period After an action potential, sodium voltage-gated channels are closed and sodium cannot move into the axon. It is therefore impossible during this time for a further action potential to be generated. This time period, called the refractory period serves two purposes: It ensures that an action potential can only be propagated in one direction – An action potential can only move from an active region to a resting region. It produces discrete impulses – A new action potential cannot be generated directly after the first. It ensures action potentials are separated from one another. It limits the number of action potentials – action potentials are separated from one another, therefore there is a limited amount that can pass along a neuron in a given time. All or nothing principle Nervous impulses are all or nothing responses A stimulus must exceed a certain threshold value to trigger an action potential A stimulus that exceeds the threshold value by a significant amount, will produce the same strength of action potential as if it has only just overcome the threshold value A stimulus can therefore only produce one action potential An organism can perceive different types of stimulus in two ways: The number of impulses in a given time (larger stimulus, more impulses per second) Having neurons with different threshold values – depending on which neurons are sending impulses, and how frequently impulses are sent, the brain can interpret the strength of the stimulus Section 10. 6/10. 7 – Structure and function of the synapse / Transmission across a synapse A synapse occurs where a dendrite of one neuron connects to the axon of another Structure of a synapse Synapses use neurotransmitters to send impulses between neurons The gap between two neurons is called the synaptic cleft The neuron that produces neurotransmitters is called the presynaptic neuron The axon of the presynaptic neuron ends in a presynaptic knob The presynaptic knob consists of many mitochondria and endoplasmic reticulum These organelles are required to produce neurotransmitters which are stored in synaptic vesicles Synaptic vesicles can fuse with the presynaptic membrane releases the neurotransmitter Functions of synapses †¢ A single impulse from neuron can be transmitted to several other neurons at a synapse. This means that one impulse can create a number of simultaneous responses †¢ A number of different impulses can be combined at a synapse. This means that several responses can be combined to give on single response Neurotransmitters are made in the presynaptic cleft only When an action potential reaches the presynaptic knob, it causes vesicles containing the neurotransmitter to fuse with the presynaptic membrane The neurotransmitter will the diffuse across the synaptic cleft The neurotransmitter then bind with receptors on the postsynaptic membrane, in doing so generating a new action potential in the postsynaptic neuron Features of synapses Unidirectionality Impulses can only be sent from the presynaptic membrane to the postsynaptic membrane Summation †¢ Spatial summation Different presynaptic neurons together will release enough neurotransmitter to exceed the threshold value to form an action potential †¢ Temporal summation – One neuron releasing neurotransmitter many times over a short period. Eventually the neurotransmitter will accumulate so as to overcome the threshold value of the postsynaptic membrane. Therefore generating a new action potential Inhibition Some postsynaptic membranes have protein channels that can allow chloride ions to diffuse into the axon making it more negative than usual at resting potential. This type of hyperpolarisation inhibits the postsynaptic neuron from generating a new action potential. The importance of these inhibitory synapses is that it allows for nervous impulses to be controlled and stopped if necessary Transmission across a synapse When the neurotransmitter across a synapse is the chemical acetylcholine it is called a cholinergic synapse Acetylcholine is made up of acetyl (ethanoic acid) and choline Cholinergic synapses are more common in vertebrates Cholinergic synapses occur in the central nervous system and at neuromuscular junctions 1. When an action potential reaches the presynaptic knob, calcium channels open allow calcium to diffuse into the presynaptic knob 2. The influx of calcium ions causes presynaptic vesciles containing acetylcholine to fuse with the presynaptic membrane, releasing the neurotransmitter into the synaptic cleft 3. Acetylcholine diffuses across the cleft and fuses with receptor sites on sodium channels found on the presynaptic membrane. When they do so, the sodium channels open, allowing sodium ions to diffuse along their concentration gradient into the postsynaptic knob. 4. The influx of sodium ions, generates a new action potential in the postsynaptic neuron 5. Acetylcholinesterase hydrolyses acetylcholine back into the acetyl and choline which will the diffuse back across the synaptic cleft into the presynaptic neuron. In this way acetylcholine can be recycles and reused and also is prevented from continuously generating new action potentials on the postsynaptic neuron. 6. ATP is released by mitochondria, providing energy to recombine acetyl and choline. Sodium channels on the postsynaptic membrane are now closed due to the absence of acetylcholine attached to receptor sites. Section 11. 1 – Structure of skeletal muscle There are three types of muscle in the body: Cardiac muscle which is found only in the heart Smooth muscle which is found in the walls of blood vessels Skeletal muscle which is attached to bone and is the only type of muscle under conscious control Muscles are made up of many muscle fibres called myofibrils If the cells of muscles were joined together from the end of one cell to another, the point between cells would be a point of weakness Because of this, the muscle cells are fused together into muscle fibres Cells of the same myofibrils share the same nuclei as well as cytoplasm (sarcosplasm). Within the sacroplasm are many mitochondria as well as endoplasmic reticulum Microscopic structure of skeletal muscle Myofibrils are made up of two types of protein filament Actin – thinner, consists of two strands twisted around each other Myosin – thicker and is made up of long rod shaped fibres with bulbous heads projecting outwards Myofibrils have coloured bands The isotropic (I) bands appears lighter since it consists only of actin (no overlap) The anisotropic (A) bands are darker since this is where acting and myosin overlap The H zone is the region in the centre of the sarcomere that is lighter in colour since there is only myosin The z line lies at the centre of the I bands Types of muscle fibre Slow-twitch fibres – Contract more slowly, less powerful. Adapted for endurance/aerobic respiration so less lactic acid forms Adaptations include: Large store of myoglobin, Supply of glycogen, Rich supply of blood vessels, Numerous mitochondria Fast-twitch – Contracts more rapidly with more power but only for a short period of time. Adapted for intense exercise by: Having hicker and more numerous myosin filaments, having a high concentration of enzymes used for anaerobic respiration, a large store of phosphocreatine to provide phosphate to make ATP Neuromuscular junctions Many neuromuscular junctions are spread through the muscle for simultaneous contraction Each muscle fibre has one motor neuron associated with it. The muscle fibre and the neuron make up one motor unit When only a small force is needed only a few motor units are stimulated When a nerve impulse reaches the neuromuscular junction, the synaptic vesicles join with the presynaptic membrane and release acetylcholine which diffuses across to the postsynaptic membrane and stimulates it to allow sodium ions to enter. The acetylcholine is then broken down by Acetylcholinesterase and then diffuses back into the presynaptic neuron. Section 11. 2 contraction of skeletal muscle During muscle contract, actin and myosin slide past each other; hence its name the sliding filament mechanism Evidence for the sliding filament mechanism When a muscle contract, the following changes occur to the sarcomere: The I band becomes narrower The z lines move close to one another The h band becomes narrower The a band does not change as this band is determined by the width of the myosin Myosin is made up of two different types of protein 1. A fibrous protein arranged into the filament called the tail 2. A globular protein that forms a head at each end Actin is a globular proteins thats molecules are arranged into two chains that twist around each other in a helical manner Tropomyosin forms long thin stands that s wound around the actin molecule The process of muscle contraction has a three main stages: Stimulation, contraction and relaxation Muscle stimulation When an action potential reaches the neuromuscular junctions, Calcium ion channels open and calcium ions move into the synaptic knob The Calcium ions cause the synaptic vesicles to move to the presynaptic membrane and fuse with it releasing acetylcholine Acetylcholine diffuses across the synaptic cleft and binds with receptors on the sodium voltage gated channels on the postsynaptic membrane causing it to depolarise Muscle contraction The action potential movies through the fibres by travelling through T – tubules that branch through the sarcoplasm The action potential moves through the tubules until it reach the sarcoplasmic reticulum The action potential opens calcium ions in the sarcoplasmic reticulum Calcium ions diffuse out into the muscle Calcium ions cause tropomyosin to change shape and so that the binding sites on the actin filament are exposed An ADP molecule that is attached to the myosin heads allows it to form a cross bridge with actin by binding with the receptor site Once the cross bridge is formed, the myosin head changes shape and slides the actin across. In doing so it loses the ADP An ATP molecule attaches to the myosin head and thus causes it to detach Calcium ions activate the enzyme ATPase which hydrolyses ATP and releases energy that allows the myosin head to resume its original shape. The myosin head now has a new ADP molecule that will allow it to bind with a new receptor site somewhere along the actin filament Muscle relaxation When the muscle is not being stimulated, the sarcoplasmic reticulum actively transport calcium ions back into it The lack of calcium ions means that tropomyosin can establish its original position, covering the myosin head binding sites Energy supply Energy is needed for the movement of myosin heads and the active transport of calcium ions ATP often needs to be generated anaerobically Phosphocreatine provides inorganic phosphate molecules to combine with ADP to form ATP Section 12. 1 – Principle of homeostasis The maintenance of a constant internal environment By maintaining a relatively constant environment (of the tissue fluid) for their cells, organisms can limit the external changed these cells experience thereby giving the organisms a degree of independence. What is homeostasis? Maintaining the volume, chemical make up and other factors of blood and tissue fluid within restricted limits There are continuous fluctuations; however, they occur around a set point Homeostasis is the ability to return to that set point thus maintaining equilibrium The importance of homeostasis Enzymes and other proteins are sensitive to changes in pH and temperature Water potential of blood and tissue fluid should be kept constant to ensure cells do not burst or shrink due to a net movement of water (osmosis) Maintaining a constant blood glucose concentration ensures that the water potential of the blood remains the same Independence of the external environment – a wider geographical range and therefore a greater chance of finding food shelter, etc Mammals – homeostasis allows them to tolerate a wide range of conditions Control mechanisms The set point is monitored by: 1. Receptor 2. Controller brain analyses and records information from a number of different sources and decides on the best course of action 3. Effector – brings about the change to return to set point 4. Feedback loop – informing the receptor of the changes in the system brought about by the effector Section 12. 2 Thermoregulation Mechanisms of heat loss and gain Production of heat – Metabolism of food during respiration Gain of heat from the environment – Conduction, convection (surrounding air/fluid), Radiation (electromagnetic waves particularly infrared) Mechanisms for losing heat Evaporation of water Conduction – to ground/solid Convection convection (to surrounding air/fluid), Radiation Endotherms derive most heat energy from metabolic activities Ectotherms – obtain most heat from the external environment Regulation of body temperature in Ectotherms Body temp fluctuates with the environment Controlled by exposure to the sun Shelter to the sun/burrows at night/obtains heat from the ground and very little from respiration. Can sometimes change colour to alter heat that is radiated Regulation of body temperature in Endotherms Most heat gained through internal metabolic activities Temperature range 35 – 44 oC – Compromise between higher temperature where enzymes work more rapidly and the amount of energy needed (hence food) to maintain that temperature Conserving and gaining heat in response to a cold environment Long term adaptations: Small SA:V ration Therefore mammals and birds in cold environments are relatively large Smaller extremities (e. g. ears) thick fur, feathers or fat reserves to insulate the body Rapid changes: Vasoconstriction – reducing the diameter of arteries/arterioles Shivering – in voluntary rapid movements and contractions that produce he energy from respiration Raising hair – enables a thick layer of still air to build up which acts as a good insulator. Behavioural mechanisms – bathing in the sun Decreased sweating Loss of heat in response to a warm environment Long term adaptations: Large SA:V ratio so smaller animals are found in warmer climates Larger extremities Light coloured fur to reflect heat Vasodilation – Arterioles increase in diameter, more blood reaches capillaries, more heat is therefore radiated away Increased sweating – Heat energy is required to evaporate sweat (water). Energy for this comes from the body. Therefore, removes heat energy to evaporate water Lower body hair – Hair erector muscles relax. Hairs flatten, reduces the insulating layer of air, so more heat can be lost to the environment Behavioural mechanisms – seeking shade, burrows, etc Control of body temperature Mechanisms to control body temperature are coordinated by the hypothalamus in the brain The hypothalamus has a thermoregulatory centre divided into two parts: A heat gain centre which is activated by a fall in body temperature And a heat loss centre which is activated by an increase in temperature The hypothalamus measures the temperature of blood passing through it Thermoreceptors in the skin also measure the temperature Impulses sent to the hypothalamus are sent via the autonomic nervous system The core temperature in the blood is more important that the temperature stimulating skin Thermoreceptors Section 12. 3/12/4 – Hormones and the regulations of blood glucose/Diabetes and its control Hormones are produced by glands (endocrine glands) which secrete the hormones into the blood The hormones are carried in the blood plasma to the target cells to which they act. The target cells have complementary receptors on the cell surface membrane Hormones are affective in small quantities set have widespread and long-lasting affects Some hormones work via the secondary messenger model: 1. The hormone (the first messenger) binds to receptors on the cell surface membrane, forming a hormone-receptor complex 2. The hormone-receptor complex activates an enzyme inside the cell that produces a secondary messenger chemical 3. The secondary messenger acts within the cell produces and a series of changes Both glucagon and adrenaline work by the secondary messenger model Adrenaline as a secondary messenger 1. The hormone adrenaline forms a hormone-receptor complex and therefore activates an enzyme inside the cell membrane 2. The activated enzyme the converts ATP to cyclic AMP which acts as the secondary messenger.

Marketing Essay Example | Topics and Well Written Essays - 250 words - 48

Marketing - Essay Example Further, the retail store provides incentives coupons on its website periodically that can be used only in-store, thus prompting the online consumers to visit the bricks-and-mortar retail stores. The household catalog strongly iterates the availability of products online, providing promotional codes in the catalog that can be used online. The promotional function integrates all of the marketing messages so that customers find consistency in how the business is positioned against competition stemming from its different marketing channels. JCPenney positions on price and affordability against its competition, and the majority of integrated promotions for all three channels focus on pricing differentiation. It could confuse the brand concept if the business used multiple promotional strategies. Promotions are not different in-store, in the catalog, or online since the company maintains a very wide target demographic. Because the business carries products relevant to many different lifestyles and age groups, it must adopt a mass market promotional strategy rather than limiting the business to niche marketing or market

Electronic Banking Case Study Example | Topics and Well Written Essays - 2000 words

Electronic Banking - Case Study Example According to New Dawn Magazine (1995, pg. 1), "Money - in the traditional sense no longer exists. It died two decades ago when Richard Nixon forever abolished the gold standard. Since then, money as we once knew it has been replaced by an unstable new global medium of exchange that is called 'megabyte money'... megabyte money is a threat not only to our country's long-term growth and prosperity, but to the individual as well." The public now has quite a few electronic money counterparts available at their disposal. The United States Bureau of Engraving and Printing still prints greenbacks in sheets of 32. "In fiscal 2007, the government will print about 9.1 billion individual bills. But 95 percent is to replace worn currency, not to expand the supply. THE BUCK STARTS HERE, say signs on some printing presses. In reality, today's buck usually begins (and ends) as a mere data entry" (Samuelson, 2007, pg. 1). * U.S. currency (dollar bills of all amounts) totaled $784 billion in 2006, but probably half or more is held outside the United States by foreigners who prize dollars--especially $100 bills--as a store of value. That suggests that less than $400 billion in currency supports a $13 trillion economy. In 1970, the economy's relative need for cash was almost twice as high. * In 2005, Americans held 1.7 billion credit and debit cards (about seven for everyone over 15), says The Nilson Report, an industry newsletter, and in the past decade, debit-card use has soared. In 1996, checks and cash represented almost 80 percent of consumer payments, estimates Nilson; they're now less than half. (The latest firm figures for 2005 show all paper payments at 50.3 percent of the total, with cash at 20.7 percent; by 2010, Nilson expects electronic payments to exceed 70 percent of the total.) * From a peak of almost 50 billion in 1995, the number of checks written in the United States fell to 36.6 billion in 2003, while the number of electronic payments rose from 15 billion to 44 billion, estimates the Federal Reserve. (The Fed survey doesn't directly measure cash use.) Companies are even marketing products to kids that are supposed to help get them used to the cashless society that supposedly lies ahead. For instance, Mastercard came out with a credit card made just for children. One of the biggest dangers of this card is that it can allow children to go into debt by purchasing and consuming large amounts of products without using cash. "Supporters regard the cards, which are issued by Bluecorner, as the natural step in an increasingly cashless society. They argue that the prepayment cards will familiarise children with plastic without spending too much. The cards are designed to get children used to the fact that cash is obsolete and their money, and the amount they are allowed to spend is controlled by someone else who also profits from their spending" (Watson, 2006, pg. 1). The Role of Information Systems According to New Dawn Magazine (1995, pg. 1), "Certainly there are jumps in technology that have facilitated this. For instance, a product that we market at Norwest is a debit card. It is a Visa Card (credit) but it's a debit card, so the money comes out of your checking account. This year [1994] across the country, Visa's volume (the number of times that the Visa Card is used) is up massively. Check