162. Physiology of Aging and Oxidative Stress, Prevention of Aging and Physiology of Yoga – Quiz

📌 Professor’s Notes: Quick Revision

High-yield revision notes for rapid review before university examinations.

• Aging is a progressive decline in cellular function, tissue repair and physiological reserve. It results from interaction of genetic, molecular, environmental and lifestyle factors. Important changes include DNA damage, telomere shortening, mitochondrial dysfunction, oxidative stress, altered proteins and reduced DNA repair.
• No single theory explains aging. Important theories include mutation theory, pleiotropic antagonism, ecological theory and random damage theories. Current understanding considers aging to result from several interacting mechanisms, including genetic changes, oxidative stress, inflammation and mitochondrial dysfunction.
• Telomeres protect chromosome ends and shorten progressively with repeated cell division. Most somatic cells have limited telomerase activity, whereas stem cells and germ cells maintain telomere length more effectively. Excessive shortening promotes cellular senescence or cell death.
• Excess calorie intake promotes obesity, insulin resistance and chronic inflammation. Moderate calorie restriction without malnutrition may improve metabolic efficiency, mitochondrial function and insulin sensitivity. Severe restriction should be avoided because it can cause nutrient deficiency and loss of lean body mass.
• Oxidative stress occurs when reactive oxygen species exceed antioxidant defenses. Important reactive species include superoxide, hydrogen peroxide and hydroxyl radicals. They can damage DNA, proteins, lipids and cell membranes and contribute to mitochondrial dysfunction and cellular aging.
• Major antioxidant defenses include superoxide dismutase, catalase and glutathione peroxidase. Vitamin C, vitamin E, carotenoids and selenium also contribute to antioxidant protection. The hydroxyl radical is particularly damaging.
• Free radicals have a useful physiological role in phagocytosis. Activated neutrophils and macrophages generate reactive oxygen species through the nicotinamide adenine dinucleotide phosphate oxidase system to destroy microorganisms. Excessive production, however, damages host tissues.
• Lipid peroxidation is oxidative damage to polyunsaturated fatty acids in cell membranes. It decreases membrane integrity, alters fluidity and permeability, and interferes with cellular transport and function.
• Atherosclerosis is a chronic inflammatory disease involving lipid accumulation and fibrous tissue in arterial walls. Major risk factors include hyperlipidemia, obesity, diabetes mellitus, hypertension, smoking, physical inactivity and advancing age. It increases the risk of myocardial infarction, stroke and peripheral arterial disease.
• In older adults, physiological reserve declines in several systems. Important changes include reduced renal filtration, reduced lung and chest-wall compliance, decreased cardiovascular reserve, impaired immune function, loss of muscle and bone mass, reduced sensory function and slower neurological responses.
• Healthy aging is promoted by balanced nutrition, regular exercise, adequate sleep, stress management, avoidance of tobacco, moderation or avoidance of alcohol, vaccination and appropriate screening. Exercise improves cardiovascular fitness, muscle strength, bone health, insulin sensitivity and functional independence.
• Yoga combines postures, breathing, concentration and self-awareness. It may improve flexibility, balance, respiratory efficiency, autonomic regulation, sleep and psychological well-being and should complement, not replace, evidence-based medical treatment.
• Hatha yoga emphasizes postures and breathing; Raja yoga emphasizes mental discipline and includes Yama, Niyama, Asana, Pranayama, Pratyahara, Dharana, Dhyana and Samadhi. Integral yoga emphasizes harmonious development of physical, mental, emotional and higher aspects of life.