PYC2603 Revised Chapter 3 Longevity and Physiological aging PDF

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Revised Chapter 3 Longevity and Physiological aging

Revised Chapter 3 Longevity and physiological aging. -theories of biological aging -sexual and reproductive functioning

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Orientation: The nature of individuals’ biological aging and life expectancy determined by complex interaction between genetical (biological) and psychological characteristics, and socioeconomic / environmental factors; this interaction brings individual differences strongly to the fore.

THEORIES OF BIOLOGICAL AGING

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Outcomes: knowledge of the genetic and environmental factors, and the lifestyle factors, that could influence life expectancy / rate of aging & what will improve the quality of later years. Theories of biological aging and why some people ‘age well’ and others ‘age quickly’. Sensorimotor changes (vision, hearing, muscular strength, endurance, reaction time and coordination). How these changes are dealt with so that life still has meaning. 

theories of biological aging

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genetic-programming theories

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variable-rate theories

comparing genetic-programming and variable reate theories

Theories of biological aging:     o o

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Questions of longevity and quality of life intimately connected with what happens to body as we age. As people age, their physical differences increase. The onset of senescence – the period of the life span marked by obvious declines in body functioning generally associated with aging – varies greatly. Two theories: Genetic programming theory Variable rate theory Genetic-programming theories: Bodies age according to a normal developmental timetable built into the genes. Species pattern of aging predetermined and inborn, subject to only minor modifications. Genetically decreed maximum lifespan. Hayflick’s experiment with cells which go through same aging process as body implies environmnet have little or no impact

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Failure of human body may come through programmed senescence, specific genes “switch off”, eg. hearing, sight, motor control etc. Biological clock may act through genes which control hormonal changes, or cause problems in immune system, leaving the body vulnerable to infectious disease. A variant of genetic-programming theory is that genes are programmed to enable humans to live long enough to reproduce. Gene therapy not currently viable due to various factors.

GENETIC PROGRAMMING THEORIES 1. Programmed senescence: Aging is the result of the sequential switching on and off of certain genes, with senescence being defined as the time when ageassociated deficits are manifested.

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Endocrine Theory: Biological clocks act through hormones to control the pace of aging.

3. Immunulogical theory: a programmed decline in immune system functions leads to an increased vulnerability to infectious disease and thus to aging and death.

Variablerate  

theories: (also called error theories) Aging as a result of processes that vary from person to person; influenced by both the internal and the external environments. 1. Wear-and-tear theory: Cells and tissues have vital parts that wear out. As body ages, damage to system accumulates; problems develop as ‘its parts wear out’. Stress big factor. However, body capable of selfreparation. 2. Free-radical theory: Accumulated damage caused by unstable atoms and molecules formed during metabolism radicals causes cells and eventually organs to stop functioning. Damage to cell membranes, cell proteins, fats carbohydrates and even DNA. Accumulates with age... arthritis muscular distrophy, cataracts, cancer. Parkinsons, late diabetes. Not sure whether this is a cause of or an effect of aging. 3. Rate-of living theory: The greater an organism’s rate of oxygen basal metabolism, the shorter its life span. Thus speed of metabolism determines length of life. The faster the body works, the faster it wears out. 4. Error-catastrophe theory and somatic-mutation theory: as body cells divide, errors (destruction / changes in cellular structure) occur. External and internal stressors, such as exposure to toxic substances and ultraviolet light, may alter the composition of cells, thus brain, liver other organs. Older, less able to repair themselves. Theory says that accumulation of erroneous occureces causes deteriotation of body parts, malfunctioning and death. Somatic mutation: Genetic mutations occur and accumulate with increasing age, causing cells to deteriorate and malfunction. 5. Cross-linking theory: errors are attributed to links/ bonds that form between cellular proteins. Eg: cross-linking of protein collagen makes skin less flexible.

Accumulation of crosslinked proteins damages cells & tissues, slowing down bodily processes. Diabetes in eyes, kidneys etc. Comparing Genetic-programming and variable-rate theories:  If aging is variable, the lifestyle and health practices may influence it.  Variable-rate theories seem better able to explain the wide variations in physiological aging.  Genetic programming may limit the max length of life, but environmental and lifestyle factors may affect how closely a person approaches the max & in what condition. Primary aging: is a gene-coded gradual, inevitable process of bodily deterioration that begins early in life and continues through the years. Secondary aging: consists of results of disease, abuse, and disuse – factors that are often avoidable and within people’s control.

Study Unit 3.2

SEXUAL AND REPRODUCTIVE FUNCTIONING Outcomes: understand statements: ‘human beings are sexual beings from birth to death’; ‘sexual expression can b pleasurable if older people accept their sexuality’; ‘relationships at all ages have both physical and psychological aspects of expressing love and affection, which may be highly individual’. Difference between female menopause and the male climacteric (male menopause) with intention to eliminate false ideas of this developmental period.

Menopause      

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when a woman stops ovulating and menstruating and can no longer conceive a child – generally to occur one year after the last menstrual period. Perimenopause / climacteric / “change of life”: over period of several years a woman experiences physiological changes that bring on menopause. From the thirties, production of ova begins to decline imperceptibly, Nearing 50, less estrogen is produced (small amounts of estrogen continue to be secreted, even after menopause, by the adrenal and other glands). Menstruation becomes irregular, eventually ceases. Menopause occurs when the ovaries no longer produce enough estrogen to sustain full menstrual cycles. Approx 45-55yrs (51 usually). Psychological Effects: Previously the attitude was expressed that a woman’s usefulness ends with her ability to reproduce. Women experience mixed emotions.

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Psychological problems more likely through attitude than anatomy. American culture of problem with aging is negative, although those who have gone through it is positive. For many, menopause a sign of transition into the second half of adult life, a time of role changes, greater independence, and personal growth. Some cultures ignore menopause. Some cultures welcome it, as it removes responsibilities and taboos.

The Male Reproductive system:  Testosterone levels decrease gradually from late teens onward,  Up to 30 – 40% reduction by age 70.  Male climacteric refers to a period of physiological, emotional and psychological change involving a man’s reproductive system and other body systems.  “Male menopause” is more gradual than female menopause.  The prostate gland may enlarge, causing urinary and sexual problems  Other symptoms: depression, anxiety, irritability, insomnia, fatigue, weakness, lower sexual drive, erectile failure, memory loss, and reduced muscle and bone mass and body hair.  The psychological adjustments (as for women) may stem from events such as worries, death of loved ones, illness, negative cultural attitudes to aging.  Often, lessening of sexual activity due to nonphysiological causes rather than aging.  Sperm count declines late forties or fifties.  Some men from 50 up experience erectile disfunction.

Comparison of the characteristics and effects of the female menopause with those of the male climacteric: Female menopause: Characteristics and effects Cessation of ovulation and menstruation, End of a women’s ability to reproduce

Ovulation stops permanently terminating women’s reproductive ability. Physiological changes

Male Climacteric Characteristics and effects: Physiological, emotional and psychological changes to reproduc-tive and other body systems. Prostate gland may enlarge, possible urinary and sexual problems. Although the sperm count declines, men retain their reproductive ability. Testosterone levels

such as the decline in the production of ova, estrogen and progesterone during the perimenopause (female climacteric) begin 30’s. Between +- 45-55 yrs, sudden drop in hormone production. Psychological symptoms such as depression, irritability and anxiety cannot always be associated with menopausal changes, but may, eg, be the result of attitude towards menopausal changes, illness, worries and life experiences. Cultural views of aging (those that devalue the aging process) may also play a part. Individual differences are prominent.

decrease gradually, hormone production does not suddenly drop. Decrease in testosterone levels from late teens, by the age of +- 70 years; still only a 30 to 40 % reduction. Psychological symptoms such as depression, irritability and anxiety cannot always be associated with male menopausal changes, but with, eg, work-related problems, illnesses, worries, life experiences or negative cultural views of aging.

Individual differences are prominent.

Summary & Key terms  Life expectency has increased greatly as a result of medical advances and is expected to continue to rise. Race and gender are factors in life expectancy.  Research on extension of life span in several species, especially through caloric restriction, has yielded promising results. However, survival curves suggest a geneticall detemrined limited to human life.  Biological aging in two categories: genetic programming theories, (body programmed to fail at a certain point) and variable rate theories (environment and lifestyle play important role). Sexual & reproduction functioning:  Menstrual cycle reglulates hormones until menopause 

PMS common among women in 30’s +

 Menopause (50) sharp decline in estrogen and progesterone levels, physical symptoms. 

Psychologically, women take it in their stride.

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Males, testosterone decline gradually until age 60.

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Male climacteric begins +- 10 years later than female climacteric.

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Male experience more changes in sexual functioning than women

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Male responses slower, need for sexual activity less frequent.

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Impotence and erectile disfunction increase with age....