Question 2#

What is true about baroreceptors?

a. Volume receptors can be activated in hemorrhage with reduction in left atrial pressure
b. Receptors in the aortic arch and carotid bodies inhibit the autonomic nervous system (ANS) when stretched
c. When baroreceptors are stretched, they induced increased ANS output and produce constriction of peripheral vessels
d. None of the above

Correct Answer is B


Baroreceptors also are an important afferent pathway in initiation of adaptive responses to shock. Volume receptors, sensitive to changes in both chamber pressure and wall stretch, are present within the atria of the heart. They become activated with low volume hemorrhage or mild reductions in right atrial pressure. Receptors in the aortic arch and carotid bodies respond to alterations in pressure or stretch of the arterial wall, responding to larger reductions in intravascular volume or pressure. These receptors normally inhibit induction of the autonomic nervous system (ANS). When activated, these baroreceptors diminish their output, thus disinhibiting the effect of the ANS. The ANS then increases its output, principally via sympathetic activation at the vasomotor centers of the brain stem, producing centrally mediated constriction of peripheral vessels.