A & P Lecture 8: Autonomic Nervous System

Is the ANS voluntary or involuntary

involuntary

Where does ANS control come from

Hypothalamus, limbic system, brain stem, spinal cord

Is the ANS a two-neuron or one-neuron pathway?

Two-neuron

What neurons always release ACh

Preganglionic neurons

Most sympathetic postganglionic neurons release...

Norepinephrine

Sympathetic postganglionic neurons that go to sweat glands release...

ACh

Parasympathetic postganglionic neurons release...

ACh

Chromaffin cells of adrenal medullae release...

epinephrine and norepinephrine

ANS effectors

cardiac muscle, smooth muscle, and glands

What fibers does the Somatic NS carry?

Sensory and motor

Sensory in the Somatic NS

- General somatic sensation

- Special senses

What muscles does the Somatic NS innervate

Skeletal muscle

Somatic NS: How many neurons are in the pathway

One neuron extending from CNS to skeletal muscle fiber

What system is the adrenal medulla part of?

ANS

What system is the adrenal cortex part of?

Endocrine system

How does epinephrine and NE travel in the body after released from Chromaffin cell

Blood

ANS input sources

Autonomic (visceral) sensory neurons, interoceptors

Is ANS input consciously perceived?

No

Motor movement in the ANS can be either...

excitatory or inhibitory

What is unique about tissue innervated by the ANS

Still function even if nerve supply is damaged

Role of the SNS

Fight or flight

Role of PNS

Rest and digest

Most organs are innervated by...

Both SNS and PNS

Two motor neurons in the ANS

preganglionic and postganglionic

Where is the cell body for the preganglionic neuron?

Brain or spinal cord

Are preganglionic neurons myelinated or unmyelinated?

myelinated

Preganglionic axons extend to the...

autonomic ganglion

Where is the cell body of the postganglionic neuron?

Ganglion

Are postganglionic neurons myelinated or unmyelinated?

unmyleinated

Postganglionic axons extend to the...

effector organ

Where are preganglionic cell bodies for the SNS located

Lateral horns of gray matter (T1-L2)

What is another name for the sympathetic division

thoracolumbar division

Site of synapse between preganglionic and postganglionic neuron

Sympathetic ganglia

Two major types of sympathetic ganglia

sympathetic trunk ganglia and prevertebral ganglia

Sympathetic trunk ganglia: Postganglionic neurons primarily innervate organs...

above the diaphragm

Where does the sympathetic trunk extend

Base of skull to coccyx

Sympathetic trunk ganglia in the neck

superior, middle, and inferior cervical ganglia

Position of sympathetic trunk ganglia in reference to the vertebral column

anterior and lateral

Length of preganglionic axons in the SNS

short

Length of postganglionic axons in the SNS

long

Length of preganglionic axons in the PNS

long

Length of postganglionic axons in the PNS

short

Number of paired sympathetic trunk ganglia

3 cervical, 11-12 thoracic, 4-5 lumbar, 4-5 sacral, 1 coccygeal

Superior cervical ganglion innervation

Head and heart

sweat glands, smooth muscle of eye, blood vessels of face, lacrimal glands, pineal gland, nasal mucosa, salivary glands

Middle cervical ganglion innervation

heart

Inferior cervical ganglion innervation

heart

Prevertebral ganglia are also called the...

collateral ganglia

Prevertebral ganglia position in reference to vertebral column

anterior

Prevertebral ganglia: postganglionic neurons innervate organs...

below the diaphragm

5 major prevertebral ganglia

celiac, superior mesenteric, inferior mesenteric, aorticorenal, renal

SNS pathways to connect with postganglionic neurons (4)

1. Synapse with postganglionic neurons in adjacent ganglion

2. Ascend or descend chain before synapsing

3. Pass through chain and synapse in a prevertebral ganglion

4. Pass through chain and prevertebral to reach adrenal medullae

SNS: preganglionic axons exit spinal cord via

ventral root

SNS: how to preganglionic axons leave the spinal nerve

White ramus

The white ramus connects...

ventral ramus with sympathetic ganglia

SNS: pathways for axons of postganglionic neurons (4)

1. Enter spinal nerve

2. Form cephalic periarterial nerves

3. Form sympathetic nerves

4. Form splanchnic nerves

SNS (spinal nerve pathway): postganglionic axons exit ganglia via...

gray rami

gray rami connects...

ganglia with spinal nerves

SNS (spinal nerve pathway): innervation

visceral effectors in skin of neck, trunk, limbs

SNS (periarterial nerve pathway): preganglionic axons ascend to...

superior cervical ganglion

SNS (periarterial nerve pathway): postganglionic axons form...

cephalic periarterial nerves

Cephalic periarterial nerve function

wraps around carotid artery and travels to the head

Cephalic periarterial nerves innervate...

skin of face, smooth muscle of eye, lacrimal gland, pineal gland, salivary gland

SNS (sympathetic nerve pathway): preganglionic axons synapse in...

superior, middle, inferior cervical ganglia

SNS (sympathetic nerve pathway): postganglionic axons form...

sympathetic nerves to heart and smooth muscles of bronchi and bronchioles

SNS (sympathetic nerve pathway): preganglionic axons synapse in ganglia from levels...

T2-T4

SNS (Splanchnic nerve pathway): preganglionic axons synapse on...

prevertebral ganglia

Greater splanchnic nerve: preganglionic axons from what levels

T5-T10

Greater splanchnic nerves leads to the...

Celiac ganglion

Greater splanchnic nerve forms the...

celiac plexus

greater splanchnic nerve innervates...

blood vessels to stomach, spleen, lever, kidneys, and small intestine

lesser splanchnic nerve: preganglionic axons from what levels

T10-T11

The lesser splanchnic nerve enters the...

aorticorenal and superior mesenteric ganglion

Lesser splanchnic nerve innervates...

blood vessels of small intestine and proximal colon

Least splanchnic nerve: preganglionic axons from what level

T12

What does the least splanchnic nerve enter

renal plexus

Lumbar splanchnic nerve: preganglionic axons from what level

L1-L4

The lumbar splanchnic nerve enters the...

Inferior mesenteric ganglion

Lumbar splanchnic nerve innervates...

distal colon and rectum

Splanchnic nerves to the adrenal medulla reach what cells?

chromaffin cells

The adrenal medulla acts as...

A sympathetic postganglionic nerve fiber

SNS: A single sympathetic preganglionic axon can synapse with how many postganglionic neurons

20 or even more

SNS: how many visceral effectors can a postganglionic axon terminate in?

several

E activities of SNS

Exercise

Excitement

Emergency

Embarrassment

Ejaculation

Sympathetic response (heart)

increases rate and force of contraction

Sympathetic response: Where do blood vessels constrict?

Kidneys and GI tract

Sympathetic response: Where do blood vessels dilate?

Skeletal and cardiac muscle, liver, adipose tissue

Sympathetic response favors the rapid production of...

ATP

Sympathetic response: Why are the effects more widespread than parasympathetic?

Divergence of postganglionic axons

norepinephrine remains in the synaptic cleft

Epi and NE are released into the blood

PNS: preganglionic cell body location

Nuclei of CN III, VII, IX, X

lateral gray matter of S2-S4

Another name for parasympathetic division

Craniosacral division

PNS: postganglionic cell body location

Terminal (intramural) ganglia

Where are terminal ganglia located?

Close to or within the wall of a visceral organ

Head region ganglia

Ciliary

Pterygopalatine

Submandibular

Otic

PNS (ciliary ganglia): preganglionic neuron cell bodies

oculomotor nucleus of midbrain

Where are the ciliary ganglion located?

Posterior aspect of orbit

PNS (ciliary ganglia): innervation

smooth muscles of eye (adjusting lens, constricting pupil)

PNS (pterygopalatine ganglia): preganglionic axons from...

nuclei of CN VII

PNS (pterygopalatine ganglia): innervation

nasal mucosa, palate, pharynx, lacrimal glands

PNS (submandibular ganglia): preganglionic neuron cell bodies in...

nuclei of CN VII

PNS (submandibular ganglia): innervation

submandibular and sublingual glands