Crash course : Parasympathetic Nervous System

Parasympathetic Nervous System

The "rest and digest" division of the autonomic nervous system that promotes energy conservation and body maintenance.

Craniosacral Outflow

The origin of parasympathetic nerves from the brainstem and S2-S4 spinal cord segments.

Terminal Ganglia

Parasympathetic ganglia located close to or within the target organs.

Vagus Nerve (CN X)

The primary parasympathetic nerve carrying about 75% of all parasympathetic fibers to thoracic and abdominal organs.

Oculomotor Nerve (CN III)

Cranial nerve that carries parasympathetic fibers for pupil constriction and lens accommodation.

Facial Nerve (CN VII)

Cranial nerve that carries parasympathetic fibers for tear production and salivation

Glossopharyngeal Nerve (CN IX)

Cranial nerve that carries parasympathetic fibers for salivation from the parotid gland.

Muscarinic Receptors

Type of cholinergic receptor found on parasympathetic target organs.

Miosis

Pupil constriction caused by parasympathetic activation.

Accommodation

The process of focusing the lens for near vision, controlled by parasympathetic system.

Bradycardia

Slow heart rate caused by parasympathetic activation.

Bronchoconstriction

Narrowing of bronchial tubes in the lungs caused by parasympathetic activation.

Salivation

Production of saliva stimulated by parasympathetic activation.

Gastric Secretion

Production of stomach acid and enzymes stimulated by parasympathetic activation.

Intestinal Motility

Movement of the digestive tract stimulated by parasympathetic activation.

Lacrimation

Tear production stimulated by parasympathetic activation.

Sacral Parasympathetic Outflow

Parasympathetic nerves originating from S2-S4 that control pelvic organs.

Detrusor Muscle

The smooth muscle in the bladder wall that contracts during parasympathetic urination.

Anabolic State

The energy-building state promoted by parasympathetic activation.

Ciliary Muscle

The eye muscle that controls lens shape during accommodation.

Sphincter Pupillae

The circular muscle in the iris that constricts the pupil.

Enteric Nervous System

The nervous system of the digestive tract heavily influenced by parasympathetic input.

Vagal Tone

The constant parasympathetic inhibition of the heart rate via the vagus nerve.

Cholinergic Crisis

Overstimulation of muscarinic receptors that can occur with certain toxins or drugs.

Dual Innervation

Most organs receive input from both sympathetic and parasympathetic divisions.

Homeostasis

The balanced internal state maintained by the opposing actions of the autonomic divisions.