Physiology of Parasympathetic nervous system
The parasympathetic nervous system is composed mainly of the cranial and sacral spinal nerves. The preganglionic neurons, arising from either the brain or sacral spinal cord, synapse with just a few postganglionic neurons which are located in or near the effector organ (muscle or gland). The parasympathetic nervous system is responsible for the body’s rest and digestion response when the body is relaxed, resting, or feeding. It basically undoes the work of sympathetic division after a stressful situation. The parasympathetic nervous system decreases respiration and heart rate and increases digestion. Stimulation of the parasympathetic nervous system results in-
- Construction of pupils
- Decreased heart rate and blood pressure
- Constriction of bronchial muscles
- Increase in digestion
- Increased production of saliva and mucus
- Increase in urine secretion