SNS and PNS Review

Flashcards covering the key differences and functions of the Sympathetic and Parasympathetic Nervous Systems.

Sympathetic Nervous System (SNS) Axon Length

Preganglionic axons are short, postganglionic axons are long.

Parasympathetic Nervous System (PNS) Axon Length

Preganglionic axons are long, postganglionic axons are short.

SNS Origin

Thoracolumbar region of the spinal cord (T1-L2).

PNS Origin

Craniosacral region (brainstem + S2-S4).

Cranial Nerves Carrying PNS Signals

Cranial nerves III, VII, IX, and X.

SNS Ganglia Location

Near the spinal cord (trunk or prevertebral ganglia).

PNS Ganglia Location

Near or inside the target organ.

Neurotransmitter released by all preganglionic neurons

Acetylcholine (ACh)

Neurotransmitter released by SNS postganglionic neurons

Mostly Norepinephrine (NE)

Neurotransmitter released by PNS postganglionic neurons

Acetylcholine (ACh)

White Rami Communicantes

Entry ramp for myelinated preganglionic axons.

Gray Rami Communicantes

Exit ramp for unmyelinated postganglionic axons.

Adrenergic Receptors

Receptors that respond to Epinephrine & Norepinephrine.

Alpha (α) Receptors Function

Constrict blood vessels.

Beta (β) Receptors Function

Dilate lungs or speed up heart.

PNS Effect on Body

Rest-and-digest (localized effects).

SNS Effect on Body

Fight-or-flight (systemic effects).

Adrenal Medulla Role

Releases Epinephrine (E) and Norepinephrine (NE) into the blood.

Synaptic Knob Function

Releases neurotransmitters into the synaptic cleft.

Effector Target

Cardiac muscle, smooth muscle, or glands.