Lecture 23 - Biology of Aging Lecture 23 Physiology of...

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1 Biology of Aging Lecture 23 Physiology of Aging Aging of human body Aging versus age-related diseases Gerontology versus geriatrics 1. Aging is a sum of diseases 2. Normal aging is different from pathological aging 3. Something in between: Diseases are systemic failures-weak points of anatomical and physiological design Clinical signs of aging and their relation to molecular changes Aging is very variable between individuals (genetics and environment)
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2 Age-related changes in body composition Ancient Greeks: Aging is drying
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3 Loss of organ mass apoptosis, senescence, decline in stem cell function
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4 Figure 5.2 A comparison of major body components in males aged 25 years and 70 years. The relative decreases in the water and cell solids contents reflects the loss of muscle tissue; the decrease in bone minerals reflects the loss of bone mass; and the increase in fat content reflects the greater proportion of adipose tissue in aged humans and the decreased specific gravity (S.G.).(From Fryer 1962. Columbia University Press.) Fat Water Cell solids Bone mineral Aging changes in the face Loss of muscle tone, droopy appearance Nose, ears Colored spots Wrinkles Eye sockets loose fat Gray hair Iris loses pigment Jawbone loses bone Gums recede
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5 Appearance may improve with age… Age 73 Age 30 Jane Goodall Aging changes in the skin Lucrative area of research Old skin is usually not the cause of death Important for emotional well-being, the largest organ
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6 Aging changes in the skin Wrinkles and sagging: Epidermis becomes thinner (men have thicker dermis originally, appear to age slower) Dermal papillae more shallow, fewer- less tightly attached, loose skin Less subcutaneous fat Rough striatum corneum Fewer melanocytes but melanocytes are larger Changes in connective tissues (collagen loses elasticity due to protein damage) - elastosis Loss of muscle Microvasculature changes- becomes sparse Less oil is produced by sebaceous glands, less sweat by sweat glands Skin blemishes, growths
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8 Effects of aging changes in the skin More susceptible to injury Slow wound healing (4 times slower) Loss of proliferative capacity (senescence) of keratinocytes and fibroblasts Loss of fat, changes in blood vessels- impaired thermoregulation, hypothermia Less sweat - risk of hyperthermia Skin cancer Elastosis (protein damage and crosslinking) is pronounced in sun-exposed areas (sun screen versus vitamin D) Patterns of baldness Male pattern baldness is a sex-linked characteristic that is passed from mother to child. A man can more accurately predict his chances of developing male pattern baldness by observing his mother's father than by looking at his own father.
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