Correct option is C
Answer: c) C and D only
Explanation
Baroreceptors located in the carotid sinus and aortic arch are mechanoreceptors that detect stretch (change in arterial pressure).
They play a vital role in short-term regulation of blood pressure via the baroreceptor reflex.
Let’s evaluate each statement:
A. The increased baroreceptor discharge due to high blood pressure stimulates tonic discharge of sympathetic nerves to blood vessels and heart.
Incorrect.
High BP → increased baroreceptor firing → inhibition (not stimulation) of sympathetic output → vasodilation and decreased heart rate.
So this statement reverses the effect.
B. A decline in the pulse pressure without a change in mean pressure increases the rate of baroreceptor discharge.
Incorrect.
Baroreceptors are more responsive to pulsatile (changing) pressures.
A decline in pulse pressure actually reduces receptor activation, not increases it.
C. Baroreceptors are more sensitive to pulsatile change of blood pressure than to constant blood pressure.
Correct.
Baroreceptors respond strongly to rate and magnitude of stretch (pulsatility) rather than steady pressure.
Hence, they are dynamic sensors.
D. The increased baroreceptor discharge excites the vagal innervations to the heart.
Correct.
Baroreceptor afferents → nucleus tractus solitarius (NTS) in medulla → stimulates vagal (parasympathetic) outflow → slows heart rate.
Simultaneously inhibits sympathetic tone.
