Question

Discuss one of the four parasympathetic outputs exiting out of the brainstem via cranial nerves.

Answer 1

the parasympathic nervous system activates the relaxation, or ''rest-and-digest,'' respones. roughiy the opposite of the''fight-or-flight'' response of the sympathetic nervous system , the relaxtion response invoives restoration of energy resevers and other''peace time'' functions,such as repair and reproduction. the parasympathetic nervous system controls many of these functions thorugh 4crainal nerves: the oculomotor, facial, glossopharyngeal and vagus, which ars also known as cranial nerves III, VII, IX and X.

cranial never III, the Oculomotor never

the Oculomotor never controls several muscles of the eye.As with all parasympathetic cranial nerves, its signals originate in hebrain cells, or neurons, in the brainstem andtravel down long,this extension called never's target is the eye.its parasympathetic never fibers control the muscles that dilate or consteictenlarhe or shrink--the pipils. they also control the muscles that dilate or constrict-enlarge or shrink--the piplis. they also control the muscles that change the shape of the lens to allow the eyes to focus on near or fan Objects. when the parasympathetic response is activated,muscles contactl to constrict to constrict the pipils and make the lens rounder, to optimize focusing on close objects.

cranial never VII, the facial never

the facial never has both sensory and motor nevers endings throughout the face, which are responsible for sensation and muscle movement. parasympathetic fibers in the facial nerve control a number of glands that secrete fluid or muces.One such gland is the lacrimal gland, which makes tears to keep the eyes moist. in the mouth, parasympathetic facial nerve fibers control the submaxillary/submandibular and sublingual glands, which are glands, which are glands that secrete saliva. parasympathetic fibers also stimulate the release of mucus by the numerous mucus-secreateing glands dispersed througtht the lining of the nose, mouth and throat.

cranial Never IX, the Glossopharyngeal nerves

the glossopharyngeal never has a number of functins related to taste and eating, parasympatheic fibers in this nerve control the parotid glands, the largest of the sailvary glands. salimulation evokes a good flow of saliva. in contrast, sympathetic stimulation may producr a small flow of saliva or none at all,leading to a dry mouth.

cranial never X,the vagus nerver

OF all the parasympathetic cranial nerves, the vagus never,which contains about 80 percnt of all parasympathetic fibers in the body, influencing almst every organ below the neck-- including the heart, lunges, esophagus,trachea, stomach,small intestine, first part of the colon, liver, gallbladder, pancreas and ureters. parasympathetic activation of the vagus nerve therefore has a broad range of effects, in cluding reducting the heart rate and blood pressure, increasing the production of stomach acid, stimulating the movement of food through the intestines and keeping the larynx open for breathing while constricting the air passages in the lungs.