Basic Human Anatomy and Age-Related Changes Flashcards

An elderly resident's systolic blood pressure reads 148 mmHg while supine but drops to 121 mmHg within 2 minutes of standing. This 27 mmHg drop is BEST explained by which age-related vascular change?

Answer: Decreased baroreceptor sensitivity impairing reflex vasoconstriction

Orthostatic hypotension in older adults is primarily caused by reduced baroreceptor sensitivity. Baroreceptors in the carotid sinus and aortic arch normally detect the drop in pressure upon standing and trigger rapid sympathetic vasoconstriction. With age, arterial stiffness blunts baroreceptor stretch responses, slowing or reducing the reflex — allowing BP to fall before compensation occurs. The other options either raise BP or are unrelated to positional changes.

A CNA notices that an 82-year-old resident's skin tears easily with minimal friction and that small wounds form large bruises. Which age-related dermal change is the PRIMARY structural cause of BOTH findings?

Answer: Flattening of the dermal-epidermal junction reducing adhesion

The dermal-epidermal junction (DEJ) normally has interdigitating rete ridges that mechanically lock the dermis and epidermis together, distribute shear forces, and anchor blood vessels. With aging, these ridges flatten, dramatically reducing contact surface area. This causes the epidermis to shear off with minor friction (skin tears) and allows capillaries — no longer cushioned by the interlocking structure — to rupture easily under minimal trauma (senile purpura/bruising). Subcutaneous fat loss contributes to bruising but is not the primary structural cause of skin tears.

Which of the following BEST describes why elderly residents are at higher risk for hypothermia even in moderately cool environments, compared to younger adults?

Answer: Reduced lean muscle mass lowers basal thermogenesis and blunts shivering response

Skeletal muscle is the primary organ for non-shivering thermogenesis and for shivering (the major emergency heat-generation mechanism). Age-related sarcopenia (loss of lean muscle mass) directly reduces both resting heat production and the capacity to generate heat through shivering. Additionally, peripheral vasoconstriction responses are blunted. Decreased sweat glands impair heat DISSIPATION (a hypothermia risk is the opposite), and glomerular changes do not meaningfully affect temperature.

An older adult resident is found to have decreased kidney function. Which combination of age-related renal changes MOST accurately accounts for this decline?

Answer: Loss of nephron mass combined with reduced renal blood flow due to arteriolar sclerosis

Renal function declines with age due to two concurrent structural changes: (1) nephron loss — the kidney loses approximately 30–50% of its glomeruli by age 80 through a process of glomerulosclerosis; and (2) reduced renal perfusion — afferent arterioles undergo arteriosclerosis, decreasing blood flow and GFR even in the remaining nephrons. This combination explains the clinically significant drop in creatinine clearance that necessitates medication dose adjustments in elderly patients.

A CNA is repositioning an 88-year-old resident with kyphosis. The resident's spine curves 55° anteriorly at the thoracic level. Which age-related spinal change is the PRIMARY cause of this structural deformity?

Answer: Compression and desiccation of intervertebral discs causing anterior vertebral wedging

Intervertebral discs lose water content (nucleus pulposus desiccates) and height with age. Because the anterior portion of each vertebral body bears more compressive load, the discs compress unevenly, leading to anterior wedging of the vertebral bodies themselves over time. Accumulated across multiple thoracic levels, this progressive anterior wedging produces the characteristic kyphotic curvature. Osteoporotic vertebral compression fractures can accelerate this process. Ligament calcification and facet fusion occur but are not the primary driver of kyphosis.

Which age-related change to the respiratory system explains why a healthy 78-year-old has a LOWER arterial PaO2 (partial pressure of oxygen) than a healthy 30-year-old, even at rest with no lung disease?

Answer: Reduced alveolar surface area and increased ventilation-perfusion mismatch from loss of alveolar elasticity

With aging, the elastic recoil of lung parenchyma decreases and small airways lose structural support, causing them to collapse prematurely during exhalation. This traps gas in dependent lung zones and creates V/Q (ventilation-perfusion) mismatch — some alveoli receive blood flow but inadequate ventilation, and some receive ventilation but reduced perfusion. Additionally, alveolar walls merge, reducing total surface area for diffusion (senile emphysema). The net result is a measurable drop in PaO2 with age (roughly 0.3 mmHg per year after age 30), independent of disease. Hemoglobin changes affect O2 content but not PaO2.