Question

In relation to heart rate, which parameter is affected by sympathetic, but not parasympathetic, innervation?

a) Stroke volume
b) Cardiac output
c) Heart rate
d) Blood pressure

Answer 1

Blood pressure (option d) is the parameter affected by sympathetic but not parasympathetic innervation, as the sympathetic system stimulates vasoconstriction through hormones, elevating blood pressure.

Step-by-step explanation:

In relation to heart rate, the parameter that is affected by sympathetic but not parasympathetic innervation is d) Blood pressure.

The sympathetic nervous system, through the release of hormones like epinephrine and norepinephrine, increases heart rate and stroke volume which in turn can elevate blood pressure. These hormones cause the contraction of smooth muscle in the walls of blood vessels (vasoconstriction), thus increasing the blood pressure. On the other hand, the parasympathetic system has limited impact on the systemic blood vessels, and therefore doesn't significantly influence blood pressure.