Theories of ageing

care of elderly- biological theory of ageing

1. THEORIES OF AGEING

2. BIOLOGICAL THEORY PSYCHOLOGICAL THEORY SOCIOLOGICAL THEORY

3. BIOLOGICAL THEORY Biological Ageing Defined as Ageing is a complex biological process in which changes at molecular, cellular, and organ levels result in a progressive, inevitable, and inescapable decrease in the body's ability to respond appropriately to internal and/or external stressors.

4. 1. FREE RADICAL THEORY

5. During aging, damage produced by free radicals cause cells and organs to stop functioning. A free radical is a molecule with an unpaired, highly reactive electron. One type of very reactive free radical is the oxygen free radical, which may be produced during metabolism or as a result of environmental pollution.

6. The free radical cause physiological changes of aging and a variety of diseases. Some of the molecules that may be damaged by free radicals are fats, proteins, and DNA (both in the nucleus and in mitochondria). If membrane fats are attacked, then you get the breakdown of the cell membrane. If it is a red blood cell membrane, you get hemolysis .

7. If proteins are attacked, you get the breakdown of proteins, which may result in the loss of biological function and the accumulation of “catastrophic” compounds. If DNA is attacked, you will get a mutation that may cause aging or cancer.

8. 2. ORGEL/ERROR THEORY The theory proposed by Orgel in 1963. Also known as Catastrophe Theory. Any damage to the enzyme systems that synthesize proteins in the body results in faulty protein synthesis.

9. The faulty proteins continue to accumulate in the cell until they reach a level that damages the cells, tissues, and organ When enough damage accumulates, this may result in cell malfunctioning ( aging) leading to death.

10. 3. WEAR AND TEAR THEORY The theory introduced by Dr. August Weismann in 1882. This theory presumes that body is similar to a machine, which loses function when its part wears out.

11. Years of damage to cells, tissues and organs eventually wears them out, killing both them and the body Example- Wearing out of the skeletal system such as in osteoarthritis Wear and tear can be viewed as a result of aging and not the cause of it

12. 4.CONNECTIVE TISSUE THEORY Also known as cross link theory. Introduced by Lohn Bjorksten in 1942. The accumulation of cross-linked proteins damages cells and tissue, slowing down bodily processes. Example Non-enzymatic glycosylation reactions occur when glucose molecules attach to proteins causing a chain of chemical reactions resulting in a structural change to the proteins. Loss of flexibility of connective tissue Microvascular changes in arteries

13. 1.PROGRAMMED THEORY Also known as biological clock theory. This theory proposes that every person has a biological clock that starts ticking at the time of conception. Each individual has a genetic programme specifying an unknown but predetermined number of cells division.

14. As the program plays out, the person experiences predictable changes such as atrophy of the thymus, menopause, skin changes and graying of the hair • Aging has a biological timetable or internal biological clock.

15. 2. GENE THEORY The gene theory proposes the existence of one or more harmful genes that activate overtime, resulting in the typical changes seen with aging and limiting the life span of the individual. Organism failure occurs in later life because of the presence of imperfect genes activated over lengthy periods of time. Two gene types, one supports growth and vigor, and the other supports senescence and deterioration.

16. 3. NEUROENDOCRINE THEORY Introduced by Prof Vladimir Dilman and Ward Dean This theory elaborates on wear and tear by focusing on the neuroendocrine system. This system is a complicated network of biochemicals that govern the release of hormones which are altered by hypothalamus. The hypothalamus controls various chain-reactions to instruct other organs and glands to release their hormones etc. The hypothalamus also responds to the body hormone levels as a guide to the overall hormonal activity. Accordingly, as ages the secretion of many hormones declines and their effectiveness is also reduced due to the receptors down- grading.

17. 4. IMMUNOLOGICAL THEORY Introduced by F.M Burnet in 1960s and the theory was developed by R.Walford . The immunologic theory proposes that aging is a function of changes in the immune system . The immune system weakens over time, making an aging person more susceptible to disease, increase in autoimmune disease and allergies

18. Over time, cells involved in immune function are less self- regulatory, resulting in cells being misidentified as foreign material and being attacked by the immune system’s own defenses. Eg : rheumatoid arthritis (RA) and lupus.