Question

Describe the effect that the sympathetic nervous system has on the function of the heart.

Answer 1

Sympathetic system is a part of autonomous nervous system (ANS).

Sympathetic suuply to the heart is via post ganglionic fibers from the sympathetic trunk.

Sympathetic fibers supply the SA node and AV node of the heart.

The postganglionic fiber innervating the SA node releases Noradrenaline neurotransmitter , this activate the beta 1 adrenergic receptors on the SA node and ncrease the Heart Rate . and also act on the AV node and increases the force of contraction of the heart.

Another function of sympathetic system is to maintain the Blood pressure

When the baroreceptor in the carotid sinus detect a drop in the Blood pressure , it wil activate the Sympathetic fibers , it further act on the heart and increases the heart rate and cardiac output and thereby increases the Blood pressure in to normal level.