Question

Taking the example of heart beat, justify the antagonistic action of thesympathetic and the parasympathetic nerves.

Answer 1

Pacemaker present in the heart produce action potential that results in the contraction of cardiac muscles and hence pumping of blood.

Frequency of action potential produced by the pacemaker is under the control of sympathetic and parasympathetic nervous system.

Sympathetic nervous system increase the frequency of action potential thus increasing the heart rate whereas antagonistically parasympathetic nervous system decrease the frequency of action potential thus lowering the heart beat. Both of them act antagonistically to control the heart beat.