Ninja Nerd-Autonomic Nervous System - Intro and Key Concepts

A set of practice flashcards covering the main concepts from the Autonomic Nervous System lecture, including divisions, outflows, ganglia, neurotransmitters, and the role of splanchnic nerves.

What are the two main divisions of the peripheral nervous system?

Sensory (afferent) system and motor (efferent) system.

What part of the motor system is under voluntary control?

The somatic motor system.

What part of the nervous system controls the viscera and is involuntary?

The autonomic (visceral) motor system.

How many motor neurons are required to reach an effector in the somatic vs autonomic systems?

Somatic uses one motor neuron; autonomic uses two (preganglionic and postganglionic).

Where is the alpha motor neuron located?

In the anterior (ventral) gray horn of the spinal cord.

What neurotransmitter is released by alpha motor neurons onto skeletal muscle?

Acetylcholine.

What receptor does acetylcholine act on in skeletal muscle?

Nicotinic M receptors.

What is the thoracolumbar outflow?

Sympathetic preganglionic neurons originate from T1–L2.

What is the craniosacral outflow?

Parasympathetic preganglionic neurons originate from brainstem (CN III, VII, IX, X) and S2–S4.

Which cranial nerves carry parasympathetic fibers?

Cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal), and X (vagus).

Which brainstem nucleus is associated with the parasympathetic outflow of CN III?

Edinger-Westphal nucleus.

Which brainstem nucleus is associated with the parasympathetic outflow of CN VII?

Superior Salivatory nucleus.

Which brainstem nucleus is associated with the parasympathetic outflow of CN IX?

Inferior Salivatory nucleus.

Where are the sacral parasympathetic preganglionic neurons located?

In the sacral segments S2–S4 (pelvic splanchnic nerves).

What is craniosacral outflow?

Parasympathetic outflow from brainstem and sacral regions (CN III, VI, IX, X and S2–S4).

What is a ganglion?

A group of neuron cell bodies located in the peripheral nervous system.

What is the difference between terminal/intramural ganglia and other autonomic ganglia?

Terminal or intramural ganglia are located near or inside the target organ, typical of parasympathetic innervation.

What are the two main types of sympathetic ganglia?

Chain (paravertebral) ganglia and collateral (prevertebral) ganglia.

What is the white ramus communicans?

The myelinated preganglionic sympathetic axon traveling from the ventral ramus to the chain ganglia.

What is the gray ramus communicans?

The unmyelinated postganglionic sympathetic axon exiting the chain ganglion to join the spinal nerve.

Which tissues do sympathetic postganglionic fibers innervate via chain ganglia (three examples)?

Piloerector muscles (erector pili), vasomotor fibers (blood vessels), and sudomotor fibers (sweat glands).

What is the exception to sympathetic postganglionic norepinephrine release?

Sweat glands release acetylcholine (sudomotor) instead of norepinephrine.

What is the adrenal medulla's relation to the autonomic nervous system?

It acts as a modified sympathetic ganglion; preganglionic fibers innervate chromaffin cells, releasing catecholamines into the bloodstream.

What is a splanchnic nerve?

Preganglionic sympathetic fibers that pass through chain ganglia and synapse on collateral (prevertebral) ganglia to innervate abdominal/pelvic viscera.

What organs do thoracic splanchnic nerves typically target?

Heart, lungs, and esophagus (thoracic viscera).

What is the difference in preganglionic and postganglionic lengths in sympathetic vs parasympathetic?

Sympathetic: short preganglionic, long postganglionic. Parasympathetic: long preganglionic, short postganglionic.

Where are preganglionic sympathetic cell bodies located in the spinal cord?

In the intermediolateral (intermediate lateral) column of T1–L2.

What is meant by 'synapse in chain ganglia'?

Preganglionic sympathetic fibers enter the chain ganglia, synapse on postganglionic neurons, which may then exit via gray ramus or form a splanchnic nerve.

What are the two main divisions of the peripheral nervous system?

Sensory (afferent) system and motor (efferent) system.

What part of the motor system is under voluntary control?

The somatic motor system.

What part of the nervous system controls the viscera and is involuntary?

The autonomic (visceral) motor system.

How many motor neurons are required to reach an effector in the somatic vs autonomic systems?

Somatic uses one motor neuron; autonomic uses two (preganglionic and postganglionic).

Where is the alpha motor neuron located?

In the anterior (ventral) gray horn of the spinal cord.

What neurotransmitter is released by alpha motor neurons onto skeletal muscle?

Acetylcholine.

What receptor does acetylcholine act on in skeletal muscle?

Nicotinic M receptors.

What is the thoracolumbar outflow?

Sympathetic preganglionic neurons originate from T1

–L2.

What is the craniosacral outflow?

Parasympathetic preganglionic neurons originate from brainstem (CN III, VII, IX, X) and S2

–S4.

Which cranial nerves carry parasympathetic fibers?

Cranial nerves III (oculomotor), VII (facial), IX (glossopharyngeal), and X (vagus).

Which brainstem nucleus is associated with the parasympathetic outflow of CN III?

Edinger-Westphal nucleus.

Which brainstem nucleus is associated with the parasympathetic outflow of CN VII?

Superior Salivatory nucleus.

Which brainstem nucleus is associated with the parasympathetic outflow of CN IX?

Inferior Salivatory nucleus.

Where are the sacral parasympathetic preganglionic neurons located?

In the sacral segments S2

–S4 (pelvic splanchnic nerves).

What is craniosacral outflow?

Parasympathetic outflow from brainstem and sacral regions (CN III, VI, IX, X and S2

–S4).

What is a ganglion?

A group of neuron cell bodies located in the peripheral nervous system.

What is the difference between terminal/intramural ganglia and other autonomic ganglia?

Terminal or intramural ganglia are located near or inside the target organ, typical of parasympathetic innervation.

What are the two main types of sympathetic ganglia?

Chain (paravertebral) ganglia and collateral (prevertebral) ganglia.

What is the white ramus communicans?

The myelinated preganglionic sympathetic axon traveling from the ventral ramus to the chain ganglia.

What is the gray ramus communicans?

The unmyelinated postganglionic sympathetic axon exiting the chain ganglion to join the spinal nerve.

Which tissues do sympathetic postganglionic fibers innervate via chain ganglia (three examples)?

Piloerector muscles (erector pili), vasomotor fibers (blood vessels), and sudomotor fibers (sweat glands).

What is the exception to sympathetic postganglionic norepinephrine release?

Sweat glands release acetylcholine (sudomotor) instead of norepinephrine.

What is the adrenal medulla's relation to the autonomic nervous system?

It acts as a modified sympathetic ganglion; preganglionic fibers innervate chromaffin cells, releasing catecholamines into the bloodstream.

What is a splanchnic nerve?

Preganglionic sympathetic fibers that pass through chain ganglia and synapse on collateral (prevertebral) ganglia to innervate abdominal/pelvic viscera.

What organs do thoracic splanchnic nerves typically target?

Heart, lungs, and esophagus (thoracic viscera).

What is the difference in preganglionic and postganglionic lengths in sympathetic vs parasympathetic?

Sympathetic: short preganglionic, long postganglionic. Parasympathetic: long preganglionic, short postganglionic.

Where are preganglionic sympathetic cell bodies located in the spinal cord?

In the intermediolateral (intermediate lateral) column of T1

–L2.

What is meant by 'synapse in chain ganglia'?

Preganglionic sympathetic fibers enter the chain ganglia, synapse on postganglionic neurons, which may then exit via gray ramus or form a splanchnic nerve.

What neurotransmitter is released by all preganglionic autonomic neurons?

Acetylcholine (ACh).

What receptors are found on all postganglionic autonomic neurons, responding to preganglionic ACh?

Nicotinic N receptors.

What neurotransmitter do parasympathetic postganglionic neurons primarily release, and what receptors do they act on?

Acetylcholine (ACh), which acts on Muscarinic receptors.

What neurotransmitter do sympathetic postganglionic neurons primarily release, and what receptors do they act on?

Norepinephrine, which acts on Alpha (\alpha) and Beta (\beta) adrenergic receptors (except for sweat glands which release ACh).

What are cholinergic neurons?

Neurons that release acetylcholine as