Body Fluids and Circulation Question 58
58. How do parasympathetic neural signals affect the working of the heart?
[2014]
(a) Reduce both heart rate and cardiac output.
(b) Heart rate is increased without affecting the cardiac output.
(c) Both heart rate and cardiac output increase.
(d) Heart rate decreases but cardiac output increases.
Show Answer
Answer : a
Hints & Solutions
(a) Control of heart beat by nervous system can be done by medulla oblongata. Medulla oblongata has two regulatory centre:
(i) Accelerator centre - It functions through sympathetic nervous system (SNS) and increases heart beat by the secretion of epinephrine or adrenaline.
(ii) Depressor centre - It functions through parasympathetic nervous system (PSNS) by the secretion of acetylcholine. It decreases heart beat, speed of conduction of action potential and thereby the cardiac output.
