Which phrase describes the function of a buffer?

Choice A rationale:

Buffers do not excrete weak acids; instead, they help regulate the pH of bodily fluids by preventing drastic changes in acidity or alkalinity.

Choice B rationale:

Buffers do not secrete hydrogen ions. In fact, buffers can either absorb or release hydrogen ions to maintain a stable pH.

Choice C rationale:

To convert strong acids to weak acids is the correct answer. Buffers are substances that can neutralize both acids and bases, helping to maintain a stable pH in a solution. They achieve this by accepting hydrogen ions from strong acids or donating hydrogen ions to strong bases, converting them into weaker acids or bases, respectively.

Choice D rationale:

Buffers do not convert ammonia to ammonium ions. This conversion is a part of the body's acid-base regulation system, but it is not the primary function of buffers.

Choice A rationale:

Stenosis of the heart valves typically leads to murmurs and changes in heart sounds but does not directly impact blood pressure regulation.

Choice B rationale:

Decreased adrenergic sensitivity might lead to lower heart rate and blood pressure, not an increase in systolic blood pressure as seen in this case.

Choice C rationale:

Increased parasympathetic activity would lead to decreased heart rate, not an increase in systolic blood pressure as observed in the patient.

Choice D rationale:

Loss of elasticity in arterial vessels is the correct answer. With aging, arterial walls become less flexible and more rigid due to the accumulation of calcium and collagen. This loss of elasticity results in increased systolic blood pressure, which is the top number in a blood pressure reading. The diastolic pressure, represented by the bottom number, does not usually increase significantly with age. This change is a result of arteriosclerosis, which commonly occurs in elderly individuals.