27 What is the effect direct excitation indirect excitation

27.   What is the effect [direct excitation, indirect excitation, direct inhibition, indirect inhibition] of increased firing of the aortic and carotid baroreceptors on:

o    vasomotor center

o    the cardiac inhibitory center

o    the cardiac accelerator center

o    cardiac inhibitory center

Solution

Answer=

Effect of Increased firing of Aortic & carotid baroreceptors on

1] Vasomotor center = Direct inhibition

When atrial pressure increase ,the aorta & carotid sinuses expand & stretch the baroreceptors,which increase their rate of firing

Impulses from baroreceptors ,inhibit the vasomotor center & excite vagal motor neurone causes vasodilation,decreased heart rate

2] The cardiac inhibitory center = is indirect excitation

3] The cardiac accelerator center =Indirect inhibition

Explaination= the baroreceptor reflex will be activated the loss of blood volume & concomitant decrease in systemic arterial blood pressure will be sensed by baroreceptors

The decresed placed upon these baroreceptors is communicated by way of decresed rate of firing of action potential through peripheral nerves to brainstem as a result cardiac inhibitory center inhibited & accelerator center is activated