What is the only primary effect of the parasympathetic syste

What is the only primary effect of the parasympathetic system to change cardiac output?

Solution

Our central nervous system(CNS) is divided into two main divisions depending upon the input and output sources. Whether the input is to CNS from perphery(Afferent division) or the output from CNS to perphery(Efferent division). Both of these divisions i.e. afferent and efferent comes under a division popularly known as perpheral nervous system(PNS). The efferent division is again divided into autonomic nervou system(ANS) and somatic nervous system. The ANS regulates involuntary smooth mucles, cardiac muscles and glands. ANS involves two neurons in the efferent pathway i.e. preganglionic neuron(interacts with postganglionic neuron and pass message to brain) and postganglionic neuron( interacts with target tissue). Based on positions of these neurons ANS is further subdivided into two systems i.e. sympathetic division and parasympathetic division. The sympathetic division activates fight or flight action of body by releasing norepinephrine from postganglionic neurons whereas, parasympathetic works antagonistically and release acetylcholine from its postganglionic fibers. The action of two division is balanced with each other and helps in mainting homeostasis of human system(equillibrium of body).

The parasympathetic division of ANS decrease the heart rate by releasing neurotransmitters like acetylcholine which acts on vagus nerve of heart. acetylcholine binds to the receptors and increase resting potential of nerve thus decrease heart beat. Whereas, sympathetic dvision works oppositely by secreting adrenaline or norepinepherine increase heart rate which makes heart to eject more blood. parasympathetic division works when person is on rest or relaxed. Thus, both division works in sync to maintain cardiac output depending upon the physiological condition of human body.