Question

Which of the following statements is correct regarding neural regulation of cardiac activity?
A. The cardiac centre lies in medulla oblongata in brain
B. Sympathetic nerve fibres accelerate the rate of heartbeat and parasympathetic nerve fibers retard the rate of heartbeat
C. Sensory fibres extend from the receptors present in the walls of aortic arch, carotid sinuses and vena cava to the cardiovascular centre in medulla oblongata.
D. All of the above.

Answer 1

Hint:- The main function of our heart is to contract and pump the oxygenated blood to all the parts of the body and then gets relaxed and pump the deoxygenated blood to the lungs for its purification, this cycle needs control and coordination of certain cardiac centres associated with brain.

Complete answer:
Option A, which is cardiac centre, lies in medulla oblongata in the brain is absolutely true. In the sympathetic system the nerves fibres which originates from thoracolumbar region of the spine which increases the heart rate whereas in contrast parasympathetic system the nerve fibres has preganglionic neurons that arise from neurons in the midbrain, pons and medulla oblongata which decreases the heart rate. And finally, the statement “Sensory fibres extend from the receptors present in the walls of aortic arch, carotid sinuses and vena cava to the cardiovascular centre in medulla oblongata'' which exactly same as it is mentioned so the correct option is (D) All of the above. So, by reading the extract above we can conclude that the heart is not the only factor that needs support and coordination of our brain and nerve fibres to accomplish cardiac activity. Both sympathetic and parasympathetic stimulations flow through a paired complex network of nerve fibres called cardiac plexus present near the base of the heart.

Note:- The cardiovascular system is controlled and influenced by not only an intrinsic conduction system, but also by an autonomic nervous system. The Autonomic nervous system has two parts that is a sympathetic and parasympathetic system which further has an important role in cardiac functioning.