Parasympathetic and Sympathetic Effects on the Eye, Heart, and Organs

Parasympathetic effect on the eye (iris)

Stimulates sphincter pupillae muscles; constricts pupils (miosis).

Parasympathetic effect on the eye (ciliary muscle)

Stimulates the muscle, making the lens bulge for close vision (accommodation).

Parasympathetic effect on the salivary glands

Stimulates secretion of watery saliva.

Parasympathetic effect on the heart (muscle)

Decreases rate; slows the heart.

Parasympathetic effect on the urinary bladder/urethra

Contracts bladder wall; relaxes urethral sphincter; promotes voiding.

Parasympathetic effect on the lungs

Constricts bronchioles.

Parasympathetic effect on the digestive tract organs

Increases motility and secretion by digestive glands; relaxes sphincters to promote movement of food.

Parasympathetic effect on the liver

Increases glucose uptake from blood.

Parasympathetic effect on the gallbladder

Excites (contracts) gallbladder to expel bile.

Parasympathetic effect on the penis

Causes erection (vasodilation).

Parasympathetic effect on the vagina/clitoris

Causes erection (vasodilation) of clitoris; increases vaginal lubrication.

Sympathetic effect on the eye (iris)

Stimulates dilator pupillae muscles; dilates pupils (mydriasis).

Sympathetic effect on the eye (ciliary muscle)

Weakly inhibits muscle, flattens lens for far vision.

Sympathetic effect on the salivary glands

Stimulates secretion of thick, viscous saliva.

Sympathetic effect on the heart (muscle)

Increases rate and force of heartbeat.

Sympathetic effect on the urinary bladder/urethra

Relaxes bladder wall; constricts urethral sphincter; inhibits voiding.

Sympathetic effect on the lungs

Dilates bronchioles.

Sympathetic effect on the digestive tract organs

Decreases activity of glands and muscles; constricts sphincters.

Sympathetic effect on the liver

Stimulates release of glucose to blood.

Sympathetic effect on the gallbladder

Inhibits (relaxes) gallbladder.

Sympathetic effect on the penis

Causes ejaculation.

Sympathetic effect on the vagina/clitoris

Causes vagina to contract.

Cranial nerves with parasympathetic fibers

Oculomotor (III), Facial (VII), Glossopharyngeal (IX), Vagus (X).

Ganglion and function of the oculomotor nerve (CN III)

Ganglion: Ciliary ganglion; Function: Constricts pupils and focuses the lens for near vision (accommodation).

Cranial nerve controlling tear and saliva secretion

CN VII - Facial nerve; Ganglia: Pterygopalatine (for tears) and Submandibular (for saliva).

Parasympathetic role of the glossopharyngeal nerve (CN IX)

Ganglion: Otic ganglion; Target: Parotid salivary gland; Function: Stimulates saliva secretion.

Organs controlled by the vagus nerve (CN X)

Heart, lungs, stomach, intestines, liver, and other abdominal organs.

Main effect of vagus nerve stimulation on the heart and GI tract

Heart: Decreases heart rate; GI tract: Increases motility and secretion (promotes digestion).

Cranial nerve providing majority of parasympathetic outflow

CN X - Vagus nerve (about 75% of all parasympathetic fibers).

Nerve providing most parasympathetic control of thoracic and abdominal organs

The vagus nerve (CN X).