Autonomic Nervous System

• Innervates:

Autonomic NS vs. Somatic NS

Skeletal muscle

Cell bodies in centralnervous system Peripheral nervous system Effect

+

+

Effectororgans

ACh

AChSmooth muscle(e.g., in gut),glands, cardiacmuscle

Ganglion

Adrenal medulla Blood vessel

ACh

ACh

ACh

NE

Epinephrine andnorepinephrine

Acetylcholine (ACh) Norepinephrine (NE)

Ganglion

Heavily myelinated axon

Lightly myelinatedpreganglionic axon

Lightly myelinatedpreganglionic axons

Neuro-transmitterat effector

Unmyelinatedpostganglionicaxon

Unmyelinatedpostganglionic axon

Stimulatory

Stimulatoryor inhibitory,dependingon neuro-transmitterandreceptorson effectororgans

Single neuron from CNS to effector organs

Two-neuron chain from CNS to effector organs

SO

MA

TIC

NE

RV

OU

SS

YS

TE

M

AU

TO

NO

MIC

NE

RV

OU

S S

YS

TE

M

PA

RA

SY

MP

AT

HE

TIC

SY

MP

AT

HE

TIC

ANS vs. SNS

ANS – Dual Innervation

• Most visceral organs

ANS – Antagonistic Control

Parasympathetic = D Division

• Digestion

• Defecation

• Diuresis

Sympathetic = E Division

• Excitement

• Exercise

• Embarrassment

• Emergency

Salivaryglands

Eye

Skin*

Heart

Lungs

Liverand gall-bladder

Genitals

Pancreas

Eye

Lungs

Bladder

Liver andgall-bladder

Pancreas

Stomach

Cervical

Sympatheticganglia

Cranial

Lumbar

Thoracic

Genitals

Heart

Salivaryglands

Stomach

Bladder

Adrenalgland

Parasympathetic Sympathetic

Sacral

Brainstem

L1

T1

Craniosacral

vs.

Thoracolumbar

Sympathetic vs. Parasympathetic

Eye

Lacrimalgland

Nasalmucosa

Ciliaryganglion

Pterygopalatineganglion

Submandibularganglion Submandibular

and sublingualglands

CN III

CN VIICN IXCN X

Otic ganglion

Parotid gland

Heart

Lung

Cardiac andpulmonary plexuses

Preganglionic

Postganglionic

Cranial nerve

Parasympathetic Cranial Outflow

PelvicsplanchnicnervesInferiorhypogastric plexus

Liver andgallbladder

Stomach

Pancreas

Urinarybladder and ureters

Smallintestine

Largeintestine

S2

Genitalia(penis, clitoris, and vagina)

Rectum

Celiacplexus

S4

Preganglionic

Postganglionic

Cranial nerve

Parasympathetic Cranial & Sacral Outflow

Sympathetic Division

• More organs – Abdominal and thoracic viscera

– Sweat glands

– Arrector pili

– Vascular smooth muscle

• Multiple pathways

Spinal cord

Dorsal root

Ventral root

Sympathetictrunk ganglion

Sympathetictrunk

Rib

Ventral ramusof spinal nerve

Gray ramuscommunicans

White ramuscommunicans

Thoracic splanchnic nerves

Anatomy Review

To effector

Dermal blood vessels

Skin (arrectorpili musclesand sweatglands)

Dorsal ramus ofspinal nerve

Sympathetictrunk ganglion

Lateral horn (visceralmotor zone)

Ventral root

Sympathetic trunk

Gray ramuscommunicansWhite ramuscommunicans

Ventral ramus ofspinal nerve

Synapse at the same level1

Spinal Nerve Pathway (1)SC to effectors in the skin of the neck, torso, and limbs.

To effector

Dermal blood vessels

Skin (arrectorpili musclesand sweatglands)

Synapse at a higher or lower level2

Spinal Nerve Pathway (2)SC to effectors in the skin of the neck, torso, and limbs.

Postganglionic Sympathetic Nerve Pathway SC to effectors in the thoracic cavity (esophagus, heart, lungs, and thoracic blood vessels), effectors of the skin of the head, neck viscera, and certain eye structures.

Splanchnic nerve

Collateral ganglion(such as the celiac)

Target organin abdomen(e.g., intestine)

Synapse in a distant collateral ganglionanterior to the vertebral column

3

Splanchnic Nerve PathwaySC to effectors in the abdominal and pelvic cavities.

Adrenal Medulla Pathway

Neurotransmitters

Cholinergic Receptors

Nicotinic Receptors

Muscarinic Receptors

The Effect of ACh

Adrenergic Receptors

Alpha and Beta

The Effect of NE/Epi

The Effect of NE/Epi

Distribution of the Parasympathetic Response

One to one

Sympathetic Division

Short, branchingpreganglionic axon

Preganglionicneuron

Autonomic ganglion(close to the vertebral column)

Ganglionic neuron

Long postganglionic axon

Distribution of the Sympathetic Response

One to many

Distribution of the Sympathetic Response

Duration of the Parasympathetic Response

Works fast

Duration of the Sympathetic Response

S-l-o-w

Duration of the Sympathetic Response

An Exception to the Antagonism