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PSYC 3490 (60)
Chapter 2

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PSYC 3490
Heather Jenkins

Biological Theories of Aging: • The number of caloric intake has as influence on aging • Rodents and rhesus monkeys suggest that reducing this lowers risk of premature death • In some cases results in longer life spans than normal diets • Okinawans eat 60% of normal Japanese diet and have 40 times centenarians o Also decrease in cardiovascular disease, diabetes, and cancer • Another variation of rate-of-living involves hormonal regulatory system’s adaptation to stress • A second family of ideas point to causes of aging at cellular level. • One notion focuses on the number of times cells can divide which places limits on the life span of a complex organism • There is a fixed number of divisions before dying, and the number of possible divisions drop depending on the age of donor of organism • Cells from human fetal tissue are capable of 40-60 times division, human adult is only 20 • Evidence suggests that the tip of the chromosomes, telomeres, play a major role • An enzyme, telomerase, is needed in DNA replication to fully replicate telomeres but the enzyme is usually not present in cells to with every replication telomeres becomes shorter. Eventually chromosomes become unstable and cannot replicate because telomeres become too short • Second cellular theory is cross-linking where certain proteins in human cells interact randomly and produce molecules that are linked in such a way as to make the body stiffer. • The proteins makeup one third of the protein in the body, and called collagen. As we age, the number of cross-links increase and explains why muscles like heart and arteries become stiffer with age o This process is important in the treatment of disease like hypertension • 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 o May cause cellular damage which impairs functioning of the organ or may block effects of important molecules o Some substances like antioxidants prevent the development of free radicals by preventing oxygen from combining with susceptible molecule to form free radical o Antioxidant: vitamin A, C, E and coenzyme Q o Evidence shows that ingesting antioxidants postpones age related diseases like cancer, cardiovascular disease and immune system dysfunction o But no evidence in increases life-span directly • Zheng concludes cell death offers one promising explanation for development of mobility problems • Body’s chemistry lab produces incorrect products at times and there are errors in the operation and replication of DNA • One needs not only a typical bodily physical but a psychological and sociocultural functioning • Examinations must be places
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