Question

The sympathetic and parasympathetic nervous systems are antagonistic in their actions. Give any two examples in support of this statement.

Answer 1

Sympathetic and parasympathetic nervous system have antagonistic effects on the organs. This is because of the different nature of the neurotransmitters released by the axons. In PSNS, the neurotransmitters are acetylcholine while in SNS, the neurotransmitters are adrenaline/noradrenaline. If the sympathetic nervous system excites a particular organ, the parasympathetic usually inhibits it. Example:

1. The SNS accelerates the heartbeat whereas the PS neural system slows down the heartbeat.

2. The SNS inhibits the secretion of saliva from the salivary glands whereas PNS stimulates saliva secretions.