Autonomic Nervous System Physiology Flashcards
Where do nerves exit in the Parasympathetic Division?
Brain via cranial nerves and sacral level
Where do nerves exit in the Sympathetic Division?
Thoracic and upper lumbar region
Do ANS nerves leave the cervical region?
NO
Where are parasympathetic ganglion?
NEAR the target organ
Where is the ANS controlled?
Hypothalamus in the brain
What neurotransmitter does the first synapse release, regardless of sympathetic/parasympathetic division?
Acetylcholine will bind to nictotinic cholinergic receptor and release Na+
Na+ is released into the post-synaptic cell and causes what?
Depolarization
Neurotransmitter for synapse number 2 in parasympathetic?
Acetylcholine will bind to Muscarinic cholinergic receptor (Gq receptor that increases cellular Ca++ for M1R and M3R)
M1R
Increases secretion in salivary glands and parietal cells in stomach
M3R
Smooth muscle contraction and increased secretion of exocrine glands (sweat)
M2R action
Gi inhibits adenylate cyclase and decreases cAMP
M2R function
Cardiac conduction - K+ efflux causes hyperpolarization
Decreases HR and conduction through heart
Neurotransmitter for synapse number 2 in sympathetic?
Norepinephrine binds to Adrenergic receptor
Alpha1 receptors – Gq increases Ca++
Vasoconstriction, liver increases glycogenolysis/gluconeogenesis, adipose tissue increases lipolysis, lacrimal decreases tear production, dilation of pupil via contraction of radial m. in eye
Alpha2 receptors – Gi decreases cAMP
GI contracts sphincters, relax smooth muscle, pancreas increases blood glucose with increased glucagon, platelets increase clotting and activation
Beta1 receptor
Heart - SA node increases HR and ventricles increase contractility
Salivary decreases secretions, adipose tissue increases lipolysis (ffa)
Beta2 receptors
Bronchodilation, GIGU relaxation, eye affects ciliary muscle that enhances distance vision, liver increases blood glucose
Beta3 receptors
White adipose tissue - lipolysis
Brown adipose tissue - heat production
Beta receptor action
Stimulates Gs protein, which activates adenylate cyclase and increases cAMP
What happens to sympathetic pre-synaptic cells that leave the paravertebral ganglion withOUT synapsing?
They synapse on to a chromaffin cell in the adrenal medulla
What happens at the synapse between the adrenal medulla and sympathetic pre-synaptic cell?
Pre-synaptic cell releases acetylcholine that binds to nicotinic cholinergic receptors and causes Na+ depolarization of the cell
The chromaffin cells do what?
Release epinephrine into the blood to increase the sympathetic response
Explain how a sympathetic signal arrives at the paravertebral column?
Cell bodies in the lateral horn travel out down the anterior root, to the anterior ramus, to the white ramus communicans to the paravertebral column
What are the 3 options once a sympathetic signal reaches the paravertebral column?
Synapse
Travel to another spinal level using the paravertebral column
Leave without synapsing using a splanchinc nerve
How do sympathetic nerves innervate the skin and sweat glands in the back?
Out the lateral horn, down anterior root and ramus, through the white ramus communicans to the paravertebral ganglion, through the gray ramus communicans back in to the spinal nerve and then down the posterior rami
Sympathetic distribution
All over the body - fight or flight
Parasympathetic distribution
Localized - rest and digest
Where are presynaptic cell bodies housed for the sympathetic division?
Upper lumber and thoracic lateral horns only
