How will the baroreceptor reflex function to help maintain mean arterial pressure after a blood donation?

Question

What will be an ideal response?

Answer 1

Answer: The baroreceptor reflex is triggered by baroreceptors, which are stretch-sensitive mechanoreceptors located in the walls of many of the major blood vessels. The most important of these are located in the carotid artery and aorta, although there are also some in the walls of pulmonary arteries and in the heart. These baroreceptors, under normal conditions send a steady stream of action potentials to the CNS. The cardiovascular control center in the medulla oblongata integrates these inputs, and sends out efferent signals via autonomic neurons that control heart rate, stroke volume, and vasomotor and venomotor tone, thus influencing blood pressure. Increased blood pressure causes arterial walls to stretch, increasing baroreceptor firing frequency which, through the integrating activity of the medulla oblongata, decreases output of sympathetic fibers resulting in vasodilation. In combination with an increase in parasympathetic output, this will additionally result in decreased cardiac contraction force and rate. This lowers blood pressure.