Question

9. Which is/are TRUE about the arterial baroreceptors:

A) Decreased stretch of the arterial baroreceptors triggers the “baroreceptor reflex” to dilate veins,

decreasing stroke volume

B) The “baroreceptor reflex” has very little direct effect on blood pressure in the brain since there is very

little autonomic input to the arterioles in the brain

C) Increased stretch of the arterial baroreceptors leads to increased activity of the sympathetic nerves to

the heart

D) The arterial baroreceptors are not active when mean arterial pressure is within a person’s normal at-

rest range

E) A and B

10. Which of the following is/are FALSE?

A) Sympathetic inputs to the SA node increase the rate of pacemaker potentials by

increasing the permeability of funny NA+ channels and T-type Ca++ channels

B) Parasympathetic inputs to the SA node slow pacemaker potentials by increasing K+ permeability

C) Both sympathetic and parasympathetic inputs to the SA node affect T-type

Ca++ channel permeability but in opposite directions.

D) A and B

E) None (all are true)

11. Which of the following is/are FALSE?

A) Total peripheral resistance is equal for the systemic and pulmonary circuits.

B) The pressure gradient between the aorta and the right atrium is much greater

than the pressure gradient between the pulmonary artery and the left atrium.

C) In the systemic circuit, the biggest drops in pressure are in the arterioles and capillaries.

D) As blood travels away from the heart, smooth blood flow (without fluctuations

in pressure) is first observed in the capillaries.

E) In terms of patterns of blood flow, the pulmonary and systemic circuits are in

series with each other while within each circuit blood flows in a parallel fashion

among the organs and capillary beds.

Answer 1

Option a is wrong as the Baroreceptor will only be stimulated when the stretch receptors sense increase in the stretching of the carotid or the aortic blood vessels due to increased blood pressure. Dilation of blood vessel will only inhibit the baroreceptors

Option b is the answer as the blood supply to the brain is not controlled by our baroreceptor and Marley's reflex . So it will not cause the regulation of blood flow to the brain as Brain had its own blood flow control mechanism and is not affected by the Baroreceptors . So it is the correct answer

Option c is wrong as the Baroreceptor reflex will reduce the sympathetic activity and cause the reduction in Heart rate to reduce blood pressure.

Option d is wrong as the Baroreceptors are always active but will only get stimualated when the reception senses a change in bp