Physiology of aging presentation ppt form

aging

1. PY 11.7 Physiology of Aging and Oxidative Stress SGIT

2. Name the theories of aging to understand the basic principle of each. List physiological changes in geriatric age. 3. Outline the basic mechanisms of oxidative stress. Explain the role of free radicals causing degeneration of the body. 5. Appreciate the role of antioxidants in preventing degeneration of the body. 6. Comprehend the role of free radicals in pathophysiology of common diseases LEARNING OBJECTIVES

3. AGING Gradual Deterioration of ability of carrying out Physiological Functions. It is irreversible and inevitable. It is of 2 types 1) Chronological 2) Biological--- Stress, Environment, Food (nutritional status), Lifestyle, Genes etc.

4. SIGNS OF AGING Loss of Hair Pigment Development of Pigmented area on skin Dryness and wrinkling of Skin Loss of Agility Increased body weight due to Fat Poor Vision Forgetfulness Weakness and decreased Immunity Degradation of Organs and Tissues

5. Theories of Aging The biological changes of aging are clearer than the mechanisms that mediate it. The common changes include: Chromosomal abnormalities 2. Increased DNA cross-linking 3. Increased frequency of single-strand breaks in DNA Decrease in DNA methylation 5. Loss of DNA telomeric sequences AGING

6. Increased post-translational changes in proteins Deamination , oxidation, and nonenzymatic glycation of proteins Deformation in mitochondrial structure. Aging is multifactorial There are many theories of aging that are not completely compatible in their explanation. However, they can be broadly divided into two categories: Genetic theories and Random damage theories

7. Genetic Theories of Aging Genetic theories of aging are based on programmed senescence, which means that at the time of birth the time of aging and death has been predetermined. That means the aging is preprogrammed by a biological time table. Three genetic theories have been developed recently: Mutation Theory The first one is the mutation theory. Usually animals die much before completion of their expected life span due to adverse effects of natural forces. Therefore, this theory suggests the importance of mutations that retards long survival. The mutations pile up in the genes that are transferred from generations to generations .

8. Theory of Pleiotropic Antagonism The second one is the theory of pleiotropic antagonism, which proposes that aging is caused by the harmful effects of genes. These unfavorable genetic effects are preserved for the purpose of survival and these properties are imparted prior to reproduction. Ecological Theory The ecological theory applies to the ecological conditions where external hazards are less. In such favorable environments, the mutation is such that the aging process is retarded to allow the animal to reproduce and protect the off springs.

9. Random Damage Theories The random damage theories explain that the aging is due to the loss of balance between ongoing damage and repair. The continuous tissue damage in the body occurs due to constant production of free radicals, and by the processes of oxidation and glycation. However, the damage is immediately repaired by regenerating an anti-stress mechanism. With advancement of age, especially after the age of 40 years, capacity to repair cells, tissues, and organs decline. Regenerative senescence was also suggested to be due to the arrest of the cell cycles at the G1/S phase. This is the phase in cell cycle at which synthesis of DNA starts. Thus, DNA synthesis is impaired.

10. Role of Cell Replication In recent times, the length of telomeric DNA has also been associated to cell replication. Telomeric DNA is present at the ends of chromosomes. Telomeric DNA has following important functions: Prevents chromosomal instability. Slows chromosomal fragmentation and rearrangement. Anchors chromosomes to nuclear matrix. Acts as a buffer between coding regions of DNA and the ends of the chromosomes. It is also necessary for cell divisions

11. Role of Calorie Intake Strongly implicated in aging is excess calorie consumption. Increased calorie intake after the age of 40 has been proved to facilitate aging. It has been observed that calorie restriction delays the onset of aging. The calorie restriction by about 30% of the total calorie intake has been documented to have following effects: 1. Increase in average life expectancy and maximum life span. 2. Delay in onset of age-associated diseases. 3. Decrease in deterioration of physiologic processes like immune responsiveness, glucose metabolism, muscle atrophy, etc.

12. Role of Calorie Intake 4. Influence on gene expression, protein turnover, and crosslinking . The impact of general calorie restriction is different from specific dietary restriction like restriction for fat, etc. However, calorie restriction must be supplemented with vitamins and antioxidants to prevent aging.

13. Role of Free Radicals and Oxidative Stress Due to metabolism, free radicals like peroxide and hydroxyl radicals are continuously produced in the body. These radicals damage the cells and tissues by the process of oxidation. The free radicals damage DNA and proteins and cause peroxidation of lipids in the membranes. This is called oxidative stress. However, simultaneously a scavenging system of antioxidants also exists in the body that neutralizes the toxic effects of free radicals. Antioxidants include glutathione, vitamin E, vitamin A, and vitamin C. Oxidative stress becomes more when production of oxidants is more than the generation of antioxidants. Oxidative stress promotes aging.

14. Atherosclerosis Atherosclerosis is the process of narrowing of lumen of blood vessels due to deposition of lipid materials on the inner endothelial lining of blood vessels. Atherosclerosis is the physiological process that starts almost at infancy. In childhood, atherosclerosis starts in aorta and larger arteries. As age advances, atherosclerosis starts in smaller arteries and arterioles. Due to atherosclerosis, blood supply to organs and tissues of the body decreases that causes structural and functional degenerations. This is the natural process of degeneration (aging) and death. However, the process of degeneration is facilitated by accelerated atherosclerosis in which fibrofatty plaques are deposited in greater amount in the blood vessel lumen and hyperplasia of smooth muscle of blood vessels occur. This causes premature aging and death.

15. The predisposing factors for accelerated atherosclerosis are: Hyperlipidemia (hypercholesterolemia, hypertriglyceridemia ) Obesity Diabetes mellitus Hypertension Smoking Excess eating (increased calorie intake) after 40 years of age Chronic stress Lack of exercise

16. ANTIOXIDANTS Group of Chemical Compounds that deactivate free Radicals and prevent their formation. Stimulate Immune System and protect against all diseases. These are Vitamin C Vitamin E Betacarotene Bioflavaonoids Minerals such as Selenium, Zinc, Copper etc.

17. FACTORS THAT WILL DELAY AGING Not Smoking Cigarettes Maintaining Normal Weight Regular Exercise Overall Good Nutrition