Lecture Eleven

Question 1

What ages is adulthood (young, middle and older), what are the generations, what is ageing and senescence?

Answer 1

• 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

Question 2

Why do we age?

Answer 2

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

Question 3

What are the causes of ageing and the stages of it?

Answer 3

-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

Question 4

What does ageing do to arterial elasticity?

Answer 4

-Reduction in arterial elasticity 
o	= increased stiffness of arteries and aorta 
= elevated aortic pressure 
= left ventricular hypertrophy
-Can cause an increase in increased

Question 5

What does ageing do to cardiac tissue?

Answer 5

-Cardiac tissue
o Accumulation of lipids and collagen
= Increase in cardiac muscle stiffness and less compliant

Question 6

What does ageing do to heart valves?

Answer 6

-Heart valves become less flexible
o Primarily the semilunar valves
= abnormal functioning

Question 7

What does ageing do to SA nodes?

Answer 7

-SA node cells decrease

o Electrical activity alters

Question 8

What does ageing do to heart rate?

Answer 8

-HR
o Maximum HR declines
-220 - age
-Response to epinephrine and norepinephrine declines

Question 9

What does ageing do to stroke volume?

Answer 9

-SV
o Can decline due to heart being less compliant therefore less blood being ejected
o Can also stay the same

Question 10

What does ageing do to cardiac output?

Answer 10

-CO

o Declines with age

Question 11

What does ageing do to VO2?

Answer 11

-VO2 
o	Declines from aged 50 
-Due to increased fat tissue 
-Decreased CO 
-Decrease in Physical activity

Question 12

What does ageing do to the vital capacity in the respiratory system?

Answer 12

-Vital capacity decreased 
o	Decreased ability to fill lungs 
-Inspiratory reserve volume decreases 
o	Decreased ability to empty lungs 
-Expiratory reserve volume decreases

Question 13

What is the changes in vital capacity due to?

Answer 13

-Weakened respiratory muscles
-Decreased thoracic cavity compliance (ability to stretch and expand)
o Stiffening of cartilage and ribs

Question 14

What does ageing do to the residual volume in the respiratory system?

Answer 14

-Residual volume increases
o Dead space increases
-Due to bronchioles and alveolar ducts expanding
-Loss of elasticity

Question 15

What does ageing do to gas exchange, mucous & tidal volume in the respiratory system?

Answer 15

-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

Question 16

What does ageing do to the urinary system?

Answer 16

-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

Question 17

What does ageing do to the digestive system?

Answer 17

-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

Question 18

What does ageing do to the endocrine system?

Answer 18

• Gradual decrease in secretory activity in some glands

- This maybe secondary to a general decline in physical activity

Question 19

What does ageing do to growth hormone levels and thyroid hormone levels?

Answer 19

• 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.

Question 20

What does ageing do to parathyroid hormone and the thymus gland?

Answer 20

• 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

Question 21

What does ageing do to the skin?

Answer 21

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

Question 22

What does ageing do to thermoregulation?

Answer 22

-Sebaceous gland secretions decrease
-Reduced peripheral blood flow
o Reduced ability to regulate temperature
-Increased risk of heat exhaustion and illness

Question 23

What does ageing do to the sleep/wake cycle, what stimulates melatonin secretion and whats the response?

Answer 23

-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