Question

The heart rate is increased by a nerve which belongs to the following division of nervous system.
I. Autonomic
II. Central
III. Peripheral
IV. Sympathetic

• A. I and IV only
• B. II and III only
• C. I, II, and III
• D. I, III, and IV
• E. II, III, and IV

Answer 1

The correct option is A I and IV only

The autonomous nervous system controls the heart beat rate via cardioregulatory centre in the medulla oblongata. The emergency conditions activate the sympathetic motor nerve and make the adrenal medulla release epinephrine and norepinephrine which in turn increase the heart beat rate. Hence, the nerve which increases heart beat is part of autonomic and sympathetic nervous system. The central nervous system includes brain and spinal cord only. The peripheral nervous system includes all cranial and spinal nerves; the 12 pairs of cranial nerves, except Vagus nerve, are part of the peripheral nervous system and are mostly concentrated in head, neck and facial region of the body. Vagus nerve conducts the parasympathetic motor impulses which in turn slow down the heart beat rate by the effect of acetylcholine; a neurotransmitter released by the parasympathetic nervous system.

Therefore, the correct answer is option A.