PYC4805 FINAL EXAM PREP 2021 .

BIOLOGICAL THEORIES OF AGEING AND HOW IT EXPLAINS BIOLOGICAL AND PHYSIOLOGICAL CHANGES Introduction Scientists and philosophers have for ages have observed why people grow old and why they die, this stimulated researchers to create a collection of theories based on biological and physiological processes. This included many hypothesises that have not proved accurate finding and to date about more than 300 existing theories have not provided a complete explanation of all normative changes experienced by humans. My answer will focus at the theories that are based on basic biological and psychological processes but it must also be noted that in all these developed theories there is still a shortfall of complete explanation of aging. 1. Rate of living theories This theory of aging makes apparent common sense by postulates that organisms have only so much energy to expend in a lifetime and that couch potatoes may like and use this theory as a reason why they are not physically active. The idea is that the rate of a creature's metabolism is related to how long it lives an survives. Several changes in the way hormones are produced and used in the human body have been associated with aging. Some researchers indicated significantly reducing the number of calories consumed by people and humans may increase longevity but studies conducted on rodents and monkeys shows that longer lives do not always result from reducing calories furthermore thus reduction could have an effect on the quality of one's life. Because the caloric restrictions in this research tends to be extreme it raises questions on the quality of life that would result from people who has had their diets restricted, this questions the strategy of diet restriction. These restrictions could further cause a drop in human's functionality and their ability to engage in important activities to obtain high quality of life. 2. Cellular theories a) Hayflick limit The focus here is on the number of times cells divide which is presumed to limit the lifespan. This theory has exhibited how cells grown in a laboratory culture dishes undergo a fixed number of divisions before dying and this number of possible divisions dropping depending on the age of the donor organism. This theory attests to the fact that cells from the human fetal tissue are capable of 40 to 60 divisions and cells from an adult human has a capability of only about 20. Chromosomes called telomeres play a major role in aging by adjusting the cell's response to stress and growth and when healthy they help by regulating the cell division and reproduction process. Telomeres which are small tips of chromosomes play a role because they contain an enzyme telomerase which is needed to replicate telomeres when cells divide. Eventually chromosomes become unstable when the replication of telomeres becomes shorter and cannot replicate as they become too short. Some researchers believe that in some cancer cells increase rapidly because telomeres are not able to regulate cell growth and reproduction. Chronic stress may accelerate changes that occur thereby shorten one's life. b) Cross linking This theory is based on the observation that certain proteins in human cells interact randomly thus produce molecules that are linked in a way that makes the body stiffer. A body protein which is collagen makes up roughly one third of protein in the body. Collagen in soft body tissues act much like reinforcing rods in concrete, the more cross-links there are the stiffer and less functional the tissues become and as we age the number of cross-links increases. This explains why muscles such as the heart and arteries become stiffer with age. However there is few scientific data which shows that cross-linking hinder metabolic processes that would constitute a basic course of aging. Even though cross linking occurs it has not been established whether it is the primary cause of aging. c) Free radicals A third type of cellular theory proposes that aging is caused by unstable molecules called free radicals which are highly reactive chemicals produced randomly in normal metabolism. When these free radicals interact with nearby molecules problems may arise for example they may cause cell damage to the heart by changing oxygen level in the cells. The most important evidence that free radicals may be involved in aging comes from research with substances that prevent the development of free radicals in the first place. A growing body of evidence shows that consuming antioxidants delays the appearance of age-related diseases such as cancer, cardiovascular and immune system dysfunction but there is no direct evidence yet that concludes that eating high food in antioxidants increase lifespan. 3. Programmed cell death theories These theories are based on the assumption that aging and death are built into the genetic blueprint of all organisms. Programmed cell death appears to be a function of physiological processes, the innate ability of cells to self destruct, and the ability of dying cells to trigger the key processes in other cells. There is increasing evidence that many diseases associated with aging such as Alzheimer's disease have genetic aspects. 4. Implication of developmental forces There are genetic components that the body's chemistry lab sometimes produces which are incorrect products and lead to errors occurring in the replication of DNS. Therefore from this perspective of basic developmental forces, the biological theories provide ways to describe the biological forces. The implication of this dynamic interactive process is that diagnosis and treatment of health related concerns must also include many perspectives. It is not only enough to have your physical functioning that is biological checked to establish whether you are healthy or not but you are need checkups' of psychological and social functioning. Results of all of these examinations must be placed in the context of overall lifespan. Biological involves forces which include all genetic and health related that affect development examples include menopause, facial wrinkling, greying of the hair, loss of hair and changes in major organ system. Psychological factors include all internal perceptual, cognitive emotional and personality factors that affect development furthermore these factors that affect development furthermore these forces provide us with characteristics we notice about people that make then individuals. Examples are forces provide us with characteristics we notice about people that make then individuals. Examples are forces provide us with characteristics we notice about people that make then individuals. Examples are someone who suffers from Alzheimer how people think and reason, children can be different personalities but born of same parents. and ethnic factors that affect development and further provide the overall contexts in which we develop for instance circumcision is a determiner of adulthood in certain cultures. Socio-cultural forces include interpersonal, societal, cultural Lastly life-cycle forces reflect differences on how the same event or a combination of the other two forces affect people at different points in their lives. They also provide context for developmental differences of interest in adult development and ageing. Conclusion It is clear that none of the theories discussed can fully explain the process of aging therefore also based of the above discussion one can conclude that biological aging is an accumulation of processes whose effects may be greater than sum of its parts. Therefore a unified theory approach to aging would have to account for a wide array of changes relating not only to biological forces but to other forces as well.