Question

Innervation of heart in the intact animal is primarily meant for
A. initiation of heartbeat
B. regulation of heart beat
C. release of acetylcholine only
D. release of adrenaline only

Answer 1

Hint: The network of nerves which are responsible for the functioning of heart refers to innervation of heart, that is by the sympathetic and parasympathetic fibre from peripheral branches of autonomic nervous system. This nerve network supplying the heart is known as cardiac plexus.

Complete answer:
The SA node of heart initiates the heartbeat, and electrical impulse is reached to the AV node and Purkinje fibres which are carried by nerves and then nerve help to distribute the impulse throughout the heart.

The network of nerve receives contribution from left, right vagus nerve and from sympathetic trunk, which influence the heart rate, cardiac output and contraction of force of heart, that is control under parasympathetic efferent fibres, while in case of sympathetic efferent fibres which are cardiac nerves that are comes from lower cervical and upper thoracic ganglia. The function of such cardiac nerves is to increase the heart rate, increase the forces of contraction of the myocardium.

The other innervation of heart is afferent parasympathetic fibres, which are vagal cardiac that function as feedback on blood pressure. The afferent sympathetic fibres come from upper thoracic and lower cervical ganglia which function on feedback on blood pressure and pain sensation.

The initiation of heartbeat by the SA node, which further distributes the impulse to maintain the rhythm of heartbeat. The regulation of heart beat is carried out by the innervation of the heart.

Ach or acetylcholine is released from parasympathetic nerves, which maintain the minute change in heart rate and cardiovascular function.

Adrenaline is a hormone that is produced by adrenal gland present over the kidney, released in stress conditions, which raise the heart rate, cardiac output, increase blood pressure, and raise the level of blood glucose.

Hence, the correct answer is option (B).

Note: Heart is a four chambered organ present in the thoracic cavity in between lungs on the left side. Heart pumps the blood into the whole body via a double circulation process in which blood sends oxygenated blood, which comes from the lung to the whole body and receives deoxygenated blood from the whole body and sent to the lungs for oxygenation purposes.