Anatomy of the Autonomic Nervous System

Vocabulary flashcards covering the key anatomical structures, neurotransmitters, divisions, and functions of the autonomic nervous system based on the lecture text.

Somatic Nervous System

The division of the nervous system under voluntary control that regulates skeletal muscle through a single myelinated motor neuron originating in the anterior gray horn of the spinal cord.

Autonomic Nervous System

The involuntary control system for the body's internal workings that utilizes a two-neuron pathway to regulate smooth muscle, cardiac muscle, and gland tissue.

Exteroceptors

Sensory receptors located primarily on the external part of the body that provide input to the somatic nervous system.

Enteroceptors

Sensory receptors that provide sensory input from internal organs to the autonomic nervous system.

Preganglionic Neuron

The first neuron in the two-neuron autonomic pathway, which has a myelinated axon and releases acetylcholine from the central nervous system.

Postganglionic Neuron

The second, unmyelinated neuron in the autonomic pathway that extends from a ganglion to the effector organ, exhibiting relatively slow action potential transmission speed.

Sympathetic Division

Also known as the fight-or-flight division, this branch of the autonomic nervous system helps maintain body functions during emergencies and intense muscular activity.

Parasympathetic Division

Also known as the rest and digest division, this branch of the autonomic nervous system functions to maintain, conserve, and store energy.

Acetylcholine

The primary neurotransmitter released by somatic motor neurons, all preganglionic autonomic neurons, parasympathetic postganglionic neurons, and specific sympathetic postganglionic exceptions.

Norepinephrine

The primary neurotransmitter released by most postganglionic neurons in the sympathetic division onto effector organs.

Sympathetic Postganglionic Acetylcholine Exceptions

Specific postganglionic neurons in the sympathetic division that release acetylcholine instead of norepinephrine, specifically innervating erector pili muscles, sweat glands, and blood vessels in skeletal muscle.

Thoracolumbar Division

Another name for the sympathetic division, based on the location of its preganglionic cell bodies in the lateral gray horns of spinal cord segments T1 through L2.

Parasympathetic Cranial Nerves

The four cranial nerves that carry parasympathetic preganglionic fibers: cranial nerve 3 (oculomotor), cranial nerve 7 (facial), cranial nerve 9 (glossopharyngeal), and cranial nerve 10 (vagus).

Cranial Nerve 10 (Vagus Nerve)

The most important nerve of the parasympathetic division, carrying long preganglionic fibers from the brain to most internal organs in the thoracic and abdominal regions.

Terminal / Intramural Ganglia

Ganglia of the parasympathetic division located within or near the target visceral effector organs.

Paravertebral Ganglia

Paired sympathetic trunk ganglia located close to the spinal cord that innervate organs above the diaphragm, such as the lungs and heart.

Prevertebral Ganglia

Unpaired sympathetic ganglia located anterior to the vertebral column near major abdominal arteries; also known as collateral ganglia.

White Ramus Communicans

A branch connecting a spinal nerve to a sympathetic ganglion that contains myelinated preganglionic axons.

Gray Ramus Communicans

A branch connecting a sympathetic ganglion back to a spinal nerve that contains unmyelinated postganglionic axons.

Adrenal Medulla

A sympathetic structure directly innervated by preganglionic neurons that releases epinephrine and norepinephrine into the bloodstream to produce widespread effects.

Celiac Ganglion

A major prevertebral ganglion located around the celiac artery right below the diaphragm, commonly referred to as the solar plexus.