Lecture Eleven Flashcards
What ages is adulthood (young, middle and older), what are the generations, what is ageing and senescence?
- Adulthood = Age 20 to death
- Young adulthood = 20-40 yrs
- Middle Aged = 40-65 yrs
- Older Adult = 65 yrs to death
- Three generations:
- 65-75
- 75-85
- 85+
- Ageing = the process of ageing
- Senescence = the process of deterioration with age
Why do we age?
o Our cells constantly divide to replace and build
-The chromosomes in those cells become damaged and deteriorate
-Therefore, our new cells are not what they used to be
o Free radical theory of ageing
-Free radicals can alter the structure of molecules
-Resulting in damage/dysfunction
o Decline of mitochondrial DNA
-Result in a decline in ATP production
o Immune system becomes less efficient
o Genetic traits
o Reduced ability to maintain homeostasis
What are the causes of ageing and the stages of it?
-We do know it is: o Complex and o Multifactorial -Three stages of ageing: o Basic homeostasis -e.g. body temp, pH o Decrease in organ mass o Decline in function -Behavioural adaptations
What does ageing do to arterial elasticity?
-Reduction in arterial elasticity o = increased stiffness of arteries and aorta = elevated aortic pressure = left ventricular hypertrophy -Can cause an increase in increased
What does ageing do to cardiac tissue?
-Cardiac tissue
o Accumulation of lipids and collagen
= Increase in cardiac muscle stiffness and less compliant
What does ageing do to heart valves?
-Heart valves become less flexible
o Primarily the semilunar valves
= abnormal functioning
What does ageing do to SA nodes?
-SA node cells decrease
o Electrical activity alters
What does ageing do to heart rate?
-HR
o Maximum HR declines
-220 - age
-Response to epinephrine and norepinephrine declines
What does ageing do to stroke volume?
-SV
o Can decline due to heart being less compliant therefore less blood being ejected
o Can also stay the same
What does ageing do to cardiac output?
-CO
o Declines with age
What does ageing do to VO2?
-VO2 o Declines from aged 50 -Due to increased fat tissue -Decreased CO -Decrease in Physical activity
What does ageing do to the vital capacity in the respiratory system?
-Vital capacity decreased o Decreased ability to fill lungs -Inspiratory reserve volume decreases o Decreased ability to empty lungs -Expiratory reserve volume decreases
What is the changes in vital capacity due to?
-Weakened respiratory muscles
-Decreased thoracic cavity compliance (ability to stretch and expand)
o Stiffening of cartilage and ribs
What does ageing do to the residual volume in the respiratory system?
-Residual volume increases
o Dead space increases
-Due to bronchioles and alveolar ducts expanding
-Loss of elasticity
What does ageing do to gas exchange, mucous & tidal volume in the respiratory system?
-Decreased gas exchange across respiratory membrane
o Alveolar walls are reduced (decreased surface area) and thickened
-Gradual rise in tidal volume
-Mucus builds up
o Cilia decrease in number and movement
What does ageing do to the urinary system?
-Kidneys decrease in size
-Amount of blood flowing through decreases
-Afferent and efferent arterioles twist and become irregular
-Glomeruli are destroyed
o By 80, 40% are not working
-Nephrons and collecting ducts structure alter by becoming shorter, thicker and irregular
-The ability to secrete and absorb declines = ability to produce concentrated urine declines
o Decreases ability to get rid of toxins
o Increased risk of dehydration
-Loss of responsiveness to ADH and Aldosterone
-Decreases in renin secretion
What does ageing do to the digestive system?
-Thinning of the mucosa and submucosa
o Less mucous secreted
-Reduced protection from toxins from the outside
-Reduced ability of the liver to detoxify
-Susceptibility to infections
-Decrease in blood supply
-Decrease in smooth muscle cells
o Reduced mobility
-Less secretions from major secretory organs
-Muscles of mastication are weakened
o Less mechanical digestion
What does ageing do to the endocrine system?
- Gradual decrease in secretory activity in some glands
- This maybe secondary to a general decline in physical activity
What does ageing do to growth hormone levels and thyroid hormone levels?
- GH levels decrease - may explain the decline in muscle and bone mass in the elderly. Greater in those that don’t exercise.
- Thyroid hormones decrease slightly – may be because of a decline in lean body mass. Damage by the immune system, due to aging, may also occur and cause a decline in T3 and T4 production.
What does ageing do to parathyroid hormone and the thymus gland?
- Increase in parathyroid hormone but reduced blood levels of Ca2+ due to reduced dietary intake = loss of bone matrix to maintain blood levels.
- Thymus gland secretes thymosin = development and maturation of the immune system
- Secretion decreases with age causing a reduced efficiency of the immune system and subsequent increase in susceptibility of infection
What does ageing do to the skin?
Integumentary System -Skin is easily damaged due to: o Collagen decreases o Epidermis thins -Skin sags and is wrinkled due to: o Loss of subcutaneous adipose tissue o Loss of dermis elastic fibres
What does ageing do to thermoregulation?
-Sebaceous gland secretions decrease
-Reduced peripheral blood flow
o Reduced ability to regulate temperature
-Increased risk of heat exhaustion and illness
What does ageing do to the sleep/wake cycle, what stimulates melatonin secretion and whats the response?
-Disturbed sleep patterns
o Possibly due to a decrease in melatonin
Melatonin
-Simulation
o A decrease in light entering the eyes
-Response
o Increase in Melatonin
o = inhibit GnRH and may regulate the sleep cycle
-Melatonin increased at night = helps us to sleep
-Melatonin decreased in the morning = helps us wake
