Autonomic Nervous System

Achalasia Cardia

-Defect in autonomic innervation of the esophagus -hyperactive lower esophageal sphincter which fails to relax on swallowing.

Disorders linked to ANS dysregulation

-HTN -PTSD -Panic disorder -Asthma -Hypotension/Vasovagal -IBS/ GI -ED

Raynaud's Disease

-abnormal constriction of blood vessels in extremities (vasospasm) -provoked by exposure to cold/emotional stress -affected body part turns white or blue, feels cold or numb. -prolonged or repeated episodes can cause sores or tissue death -fingers, toes, nose, lips, ears, nipples

Hyperreflexia

-mainly impacts those with SCI (above T5) -can develop suddenly & is life threatening. (seizures, stroke, death) -d/t sudden, strong stimulation of visceral afferents below level of injury without higher CNS toning or dampening down of the reflex. Can cause massive sympathetic discharge (high BP) -i.e. bladder hyperextension d/t catheter block

Sympathetic outflow is at the cord levels ____. The preganglionic fibers exit via______ and enter ____.

1) T1-L2/3 2) ventral roots 3) sympathetic chain

Name the 4 courses taken by preganglionic sympathetic fibers.

1. Ascend then synapse 2. synapse at level of entry 3. Descend and synapse 4. Pass through sympathetic trunk without synapsing & enter a splanchnic nerve.

In parasympathetic outflow, preganglionic fibers from the cranial division run via_____; in the spinal division run via_____.

1. CN III, VII, IX, X 2. S2-4 spinal cord

Explain how to reach sympathetic targets in the head.

1. Preganglionic fibers enter sympathetic chain at T1-L3 and ascend without synapsing. 2. When reach appropriate level, they synapse with neuron in cervical part of sympathetic chain 3. Postganglionic sympathetic fibers leave the chain ganglia & follow VASCULATURE into the head.

Match the nerve with where they synapse & with what they innervate: 1. Greater splanchnic n. 2. Lesser splanchnic n. 3. Lumbar splanchinics a. inferior mesenteric ganglion b. celiac ganglion c. superior mesenteric ganglion i. Midgut ii. Hindgut iii. Foregut

1. b, iii 2. c, i 3. a, ii

Name the 3 prevertebral or preaortic sympathetic ganglia

1. celiac 2. superior mesenteric 3. inferior mesenteric

Preganglionic fibers originate from ____, while postganglionic fibers originate from______.

1. thoraco-lumbar cord 2. all regions of the body, including the head.

Describe the sensory pathways of visceral regions.

Afferent info from visceral regions is conveyed to DRG neurons. Peripheral branch axons of spinal ganglion neurons reach viscera by following autonomics or vasculature.

Describe the sympathetic pathway to the heart.

Cervical sympathetic ganglia (as well as first 4 thoracic sympathetic ganglia) are used; postganglionic sympathetic fibers leave sym. chain directly & form a cascade of axons in the CARDIAC PLEXUS. *heart is dually innervated tissue.

The parasympathetic nervous system arises from _____ & is for _____.

Craniosacral Rest & digest

In visceral sensory neurons, cell bodies are located in

Dorsal root ganglia

TorF: All visceral organs are dually innervated

False

TorF: Sympathetics often have a relatively long preganglionic and short postganglionc fibers.

False short preganglionic, long postganglionic. Parasympathetics have long preganglionic and very short postganglionic fibers

TorF: ALL spinal nerves have white communicating ramus, but not all have gray.

False: they all have gray, not all have white.

What is the exception that pertains to the adrenal medulla?

It is directly innervated by preganglionic sympathetic fibers because it contains chromaffin cells that are modified sympathetic neurons. It is part of SNS and releases adrenalin (Epi/NE)

What are the sympathetic targets on the left side? On the right side?

L: body wall & extremities--sweat glands of skin, arector pili muscles, smooth muscles in walls of arteries/arterioles. R: head region & various organs in body--salivary glands, heart, gut

Superior cervical ganglia Middle cervical ganglia inferior cervical ganglia (stellate ganglion-when ICG fuses with 1st thoracic sympathetic ganglion)

Label the 3 cervical ganglia

Explain sympathetic pathways to pelvic organs.

Preganglionic fibers synapse in a displaced ganglia (via splanchnic nerve) & postganglionic fibers follow a plexus to reach genital/excretory targets

Explain the mechanism of referred pain.

Reference of pain to the body wall results from confusion at higher CNS levels that consciously perceive pain. This is d/t VISCERAL afferents entering spinal cord at SAME segmental level as SOMATIC afferents from the same spinal ganglion. This bulk sensory information, the signal is perceived in brain as coming from skin area innervated by most of neurons in that particular spinal ganglion (dermatome region)

Describe sympathetic pathways to abdominal organs.

Splanchnic nerve scheme is used--2nd order neurons are displaced from sym. chain to the prevertebral sympathetic ganglia. They contain PREganglionic fibers that have yet to synapse

The Autonomic Nervous system is divided into ___ & ____.

Sympathetic & parasympathetic

_____ spinal nerves are the only ones to have white communicating ramus.

T1-L3

Explain the scheme of sympathetic pathways to the body wall and extremities

T1-L3 level: 1. Preganglionic axon enters sympathetic chain via white communicating ramus, then synapses. 2. Postganglionic axon leaves sym. chain via gray communicating ramus & re-enters spinal nerve. 3. Postganglionic fibers travel with Spinal n. & leave nerve at various places that contain targets.

What is different about the prevertebral sympathetic ganglia?

They function the same, but are in an unusual location; they are displaced away from main sympathetic chain to a position anterior to the aorta.

The sympathetic nervous system arises from ____and is for _____.

Thoracolumbar Fight or Flight

TorF: The autonomic nervous system maintains homeostasis and is purely motor in function.

True

TorF: Vasculature throughout the body is innervated.

True.

The postganglionic axons of the sympathetic nervous system are called ______ because they use ______ as the transmitter at their synapses with target tissue.

adrenergic noradrenalin

The postganglionic fibers of the parasympathetic neurons are called _____ because they release ____ at their target synapses.

cholinergic acetylcholine

The autonomic nervous system functions: a. dependently b. continuously c. without conscious control d. B & C

d. It is independent

What are grey and white communicating rami?

fine connections between spinal nerve and the sympathetic chain

After synapsing in the sympathetic chain, postganglionic fibers reenter the spinal nerves via _____.

gray communicating ramus

What is visceral pain?

it is often perceived to be somatic in origin; "referred pain"

Second order neurons are located in the sympathetic chain ganglia, a.k.a. ______.

paravertebral They extend from the neck to the pelvic cavity on both sides of vertebral column

The cell body of the 1st neuron is in the CNS, its axon is the _____; it synapses with the 2nd neuron, whose cell body is in an autonomic ganglion, its axon is the ______.

preganglionic fiber post0ganglionic fiber

Describe the sacral outflow of the parasympathetic nervous system

preganglionic parasympathetic fibers arise from S2-4 spinal cord in an intermediolateral cell column & exit via VENTRAL roots. They course to small postganglionic parasympathetic pelvic ganglia that are in/close to walls of organs, then innervate & synapse. Postganglionic axons then go to targets.

The splanchnic nerve is what kind of fiber?

preganglionic sympathetic fiber

The Autonomic nervous system innervates:

smooth muscle, cardiac muscle, glands