17 - Physiology of Aging Flashcards
Describe characteristics of aging
Universal, progressive, and irreversible
Aging does not equal illness, but there’s increasing susceptibility to many conditions.
How do blood vessels change with age? What changes in concentration in the aorta?
They becomes calcified and stiffen with age - called arteriosclerosis.
Total peripheral resistance also increases with age.
Calcium content in the aorta increases with age.
How does pull contour change with arteriosclerosis?
There is increased pulse pressure, which is needed to counteract the increase in resistance in the vessels.
What are adrenal changes that occur with age?
Norepi increasesm epi is unchanged.
Aldosterone is decreased, and cortisol is unchanged.
How does blood pressure change with age?
Systolic BP increases with age and diastolic decreases with age.
MAP increases increases slightly.
Holds true for both men and women.
How does the heart change with age?
Increased weight, thickened LV, sinus/AV node infiltration with fatty connective tissue, and increase in disease.
How does cardiac output change with age?
It decreases.
How does the maximum oxygen consumption (VO2 max) with exercise change with age and why? What is this a measure of?
Declines progressively with age due to loss of lean muscle mass, loss of max HR, and deconditioning.
Measure of overall cardiopulmonary function.
How do signs of alzheimer’s/dementia differ from typical age-related changes?
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.
What is the definition of dementia? What are types of dementia?
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.
What is the prevalence of dementia?
5.3 million in the US.
What do postmortem studies chow in alzheimers patients?
Senile plaques and neurofibrillary tangles (NFT) in the cerebral cortex.
What are senile plaques and neurofibrillary tangles (NFTs)?
Senile plaques: extracellular accumulation of insoluble fragments of B-amyloid.
NFTs: intracellular accumulation of hyper-phosphorylated tau strands
Compare healthy neurons to alzheimers neurons?
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
What are the major cholinergic changes in alzheimer’s disease?
Depletion of ACh, especially in moderate to severe stages.
Decline in choline acetyltransferase (ChAT)
Loss of cholinergic neurons - muscarinic Ms receptors and nicotinic receptors.
Risk for dementia increases with what characteristics?
Age, female gender, head trauma, family history, apoliprotein E4, mutations on chrom 1, 14, or 21, and down syndrome.
Describe early onset alzheimers and the chromosomes involved. What disease does each chromosome problem correspond with?
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.
What chromosome is late-onset Alzheimer’s associated with? What gene?
Chromosome 19 - Apoliproprotein E gene.
How does total body potassium change with age for men and women?
Men: large decrease over time
Women: decreases only slightly
How does fat-free mass (ffm) change with age in men and women?
Men: decreases with age
Women: remains about the same (may slightly decrease)
How do the components of the major body compartments change with age?
There is more fat, less water, and less cell solids with age.
What are renal changes that occur with age?
Renal perfusion rate and creatinine clearance both decrease with age.
Creatinine clearance dramatically decreases with age.
What is the regression equation for creatinine clearance? What is the range of creatinine excretion per day?
133 - 0.64 (age in years) = creatinine clearance.
3.7-19.7 mg/kg body weight
What is the Cockgroft Gault equation for creatinine clearance?
(140-1ge) X weight in kg / 72 xScr
For women multiply by 0.85
What happens to the thyroid with age?
Fibrosis of the gland, cellular infiltration, and follicular atrophy.
What are ovarian changes that occur with age?
Loss of follicles, vessel obliteration, parenchymal fibrosis with atrophy of corpora lutea and albicania.
How does release of gonadotrophic hormones change with age in men and women?
Women: steep increase with menopause and then peak and decline
Men: slight increase
What hormone decreases post-menopause?
Estrogen.
What are the clinical effects of ovarian failure and estrogen loss?
Vulvar atrophy, atrophy of uterus and vagina, vasomotor instability, cessation of menses, and accelerated bone loss.
What changes occur in the male gonads?
Prostate enlargement, patchy degeneration of leydig cells and seminiferous tubules.
How does testosterone secretion change with age?
It peaks at about age 20 and then continues to decrease.
