17 - Physiology of Aging

Question 1

Describe characteristics of aging

Answer 1

Universal, progressive, and irreversible

Aging does not equal illness, but there’s increasing susceptibility to many conditions.

Question 2

How do blood vessels change with age? What changes in concentration in the aorta?

Answer 2

They becomes calcified and stiffen with age - called arteriosclerosis.

Total peripheral resistance also increases with age.

Calcium content in the aorta increases with age.

Question 3

How does pull contour change with arteriosclerosis?

Answer 3

There is increased pulse pressure, which is needed to counteract the increase in resistance in the vessels.

Question 4

What are adrenal changes that occur with age?

Answer 4

Norepi increasesm epi is unchanged.

Aldosterone is decreased, and cortisol is unchanged.

Question 5

How does blood pressure change with age?

Answer 5

Systolic BP increases with age and diastolic decreases with age.

MAP increases increases slightly.

Holds true for both men and women.

Question 6

How does the heart change with age?

Answer 6

Increased weight, thickened LV, sinus/AV node infiltration with fatty connective tissue, and increase in disease.

Question 7

How does cardiac output change with age?

Answer 7

It decreases.

Question 8

How does the maximum oxygen consumption (VO2 max) with exercise change with age and why? What is this a measure of?

Answer 8

Declines progressively with age due to loss of lean muscle mass, loss of max HR, and deconditioning.

Measure of overall cardiopulmonary function.

Question 9

How do signs of alzheimer’s/dementia differ from typical age-related changes?

Answer 9

Alzheimer’s: poor judgement and decision making, inability to manage budget, losing track of date or season, misplacing things and being unable to retrace steps to find them.

Typical: bad decision once and awhile, missing a monthly payment, forgetting which day it is and remembering it later, losing things from time to time.

Question 10

What is the definition of dementia? What are types of dementia?

Answer 10

Major neurocognitive disorder characterized by a decline in memory, cognitive function that results in and functional loss.

Alzheimers, vascular, lewy body, parkinsons, alcoholic, and frontotemporal.

Question 11

What is the prevalence of dementia?

Answer 11

5.3 million in the US.

Question 12

What do postmortem studies chow in alzheimers patients?

Answer 12

Senile plaques and neurofibrillary tangles (NFT) in the cerebral cortex.

Question 13

What are senile plaques and neurofibrillary tangles (NFTs)?

Answer 13

Senile plaques: extracellular accumulation of insoluble fragments of B-amyloid.

NFTs: intracellular accumulation of hyper-phosphorylated tau strands

Question 14

Compare healthy neurons to alzheimers neurons?

Answer 14

Healthy: robust cells with branching connections and abundant signals

Alzheimer’s neurons: dead cells full of tangles, sparse and plaque-damaged cells with withered branches

Question 15

What are the major cholinergic changes in alzheimer’s disease?

Answer 15

Depletion of ACh, especially in moderate to severe stages.

Decline in choline acetyltransferase (ChAT)

Loss of cholinergic neurons - muscarinic Ms receptors and nicotinic receptors.

Question 16

Risk for dementia increases with what characteristics?

Answer 16

Age, female gender, head trauma, family history, apoliprotein E4, mutations on chrom 1, 14, or 21, and down syndrome.

Question 17

Describe early onset alzheimers and the chromosomes involved. What disease does each chromosome problem correspond with?

Answer 17

Occurs <60 yrs old, in 7% of cases. Familial pattern with high penetrance.

Chromosome:
21 - gene BAPP
14 - gene presenilin 1
1 - gene presenilin 2

Shift cleavage site produces AB42 peptide.

Question 18

What chromosome is late-onset Alzheimer’s associated with? What gene?

Answer 18

Chromosome 19 - Apoliproprotein E gene.

Question 19

How does total body potassium change with age for men and women?

Answer 19

Men: large decrease over time

Women: decreases only slightly

Question 20

How does fat-free mass (ffm) change with age in men and women?

Answer 20

Men: decreases with age

Women: remains about the same (may slightly decrease)

Question 21

How do the components of the major body compartments change with age?

Answer 21

There is more fat, less water, and less cell solids with age.

Question 22

What are renal changes that occur with age?

Answer 22

Renal perfusion rate and creatinine clearance both decrease with age.

Creatinine clearance dramatically decreases with age.

Question 23

What is the regression equation for creatinine clearance? What is the range of creatinine excretion per day?

Answer 23

133 - 0.64 (age in years) = creatinine clearance.

3.7-19.7 mg/kg body weight

Question 24

What is the Cockgroft Gault equation for creatinine clearance?

Answer 24

(140-1ge) X weight in kg / 72 xScr

For women multiply by 0.85

Question 25

What happens to the thyroid with age?

Answer 25

Fibrosis of the gland, cellular infiltration, and follicular atrophy.

Question 26

What are ovarian changes that occur with age?

Answer 26

Loss of follicles, vessel obliteration, parenchymal fibrosis with atrophy of corpora lutea and albicania.

Question 27

How does release of gonadotrophic hormones change with age in men and women?

Answer 27

Women: steep increase with menopause and then peak and decline

Men: slight increase

Question 28

What hormone decreases post-menopause?

Answer 28

Estrogen.

Question 29

What are the clinical effects of ovarian failure and estrogen loss?

Answer 29

Vulvar atrophy, atrophy of uterus and vagina, vasomotor instability, cessation of menses, and accelerated bone loss.

Question 30

What changes occur in the male gonads?

Answer 30

Prostate enlargement, patchy degeneration of leydig cells and seminiferous tubules.

Question 31

How does testosterone secretion change with age?

Answer 31

It peaks at about age 20 and then continues to decrease.