Justify the antagonistic action of the sympathetic and the parasympathetic nerves taking heart beat as an example?
Answers
An organ related to the ANS can receive a variable amount of stimulation from both sympathetic and parasympathetic systems simultaneously, resulting in a spectrum of effects.
The muscles in the somatic nervous system don't need to have an antagonisticsystem working against them, they are simply in a state of being contracted or relaxed. This means that the neurons at the neuromuscular junction are fired and the muscle is contracted to some extent or the neuron is inhibited and the muscle is relaxed.
This means that the somatic system simply has one neural pathway that is regulated as being “on” or “off” whereas the ANS controls organs via two different neural pathways that are both in various competing degrees of being “on”.
Another reason for this difference would be that the body constantly needs to properly regulate its internal homeostatic environment. In this sense the body might be better suited for rest and digestion (parasympathetic), whereas other times might elicit the “fight or flight” system (sympathetic). Regardless, the somatic system simply needs to be capable of voluntarily contracting muscles at the given times and is not subject to such a high level of regulation.
Antagonist action defines as the ability of muscle to oppose or resist the action or effect of another muscle. Therefore in heart pacemaer is present which produce action potentials which results in the contraction of cardiac muscles, and this is under the control of sympathetic and parasypathetic nervous system. The sympathetic nervous system increase the frequency of action potential thus increases heart rate whereas antagonistically parasympathetic nervous system dcrease the frequency of action potential thus decreases heart rate.