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59 Cards in this Set

  • Front
  • Back
What are the two major subdivisions of the peripheral nervous system?
somatic and autonomic
What does the somatic nervous system control?
skeletal mm

Is the ANS voluntary or involuntary?

AKA visceral, vegetative, involuntary nervous system
What are the efferent portions of the ANS?

What type of nerves are the efferents?
sympathetic -- thoracolumbar


efferents are peripheral and motor
Where do the sympathetics and parasympathetics originate?
w/in the CNS--give off PRE ganglionic EFFERENTs exiting from the brain stem or spinal cord and terminate in the motor ganglia innervating the effector cells
What is the response of the sympathetic nervous system?
dilated pupils

broncho dilation and increased pulmonary secretions

increased heart rate and contractility

gi motility and secretions decrease and urine is retained
What is the parasympathetic response?
decreased heart beat, increased secretions, bronchioles constricted, defication, urination, erection. pupils constrict
Describe the length of the pre and post ganglion in both parasympathetic and sympathetic nervous systems.
Sympathetic: short pre gangion and long post

PS: long pre and short post
How many synapses are found in a skeletal motor axon?

Autonomic S and PS?

both have 2 neuron chain
What type of receptor are all autonomic preganglions?
What type of neurons are ALL parasympathetic postganglionic neurons?
What type of neurons are MOST sympathetic POSTganglionic neurons?
adernergic--mainly cardiac smooth mm, glands (except for sweat), nerve terminals
What is the adrenal medulla?
modified sympathetic ganglion
What types of cells are "effectors"?
cardiac, smooth mm, gland cells, sometimes endothelial and nerve terminals
What are the inhibitors of Ach release (Cholinergic)? What do they specifically inhibit?
Vesamicol inhibits vesicular storage of Ach

Botulin (botox) inhibits the release of Ach into the synapse.

Hemicholiniums inhibit Ach frm entering the presynaptic nerve terminal
How can Ach enter the nerve terminal?
by a sodium dependent carrier
What happens to Ach after it enters the synapse?
1. recycled
2. degraded
3. add on aurto receptor and fxn as negative feedback
How does a noradrenergic junction work? (NE, dopamine)

What are inhibitors (5)? What do they inhibit specifically?
Sodium dependent tyrosine uptake.

Tyrosine to DOPA via tyrosine hydroxylase.

DOPA to dopamine (into vescicle)to NE (vesicular) to synapse.

1. metyrosine: inhibits tyrosine to DOPA (inhibits tyrosine hydroxylase)

2. reserpine: inhibits vesicular uptake
(antipsychotics and antihypertension)

3. Bretylium and guanethidine (antiarrhythmia/antihypertensive) inhibits release of NE into junction

4. cocaine, tricyclic antidepressents: inhibit transport into cytoplasm
What does MAO do?
MAO will breakdown NE UNLESS it is in a vescicle
What are the uptake mechanisms in the noradrenergic junciton?
uptake 1: primary mechanism. removal of NE so it is not high all the time (inhibited by cocaine)

uptake 2: transport into the postjunctional cell (tissue)
What enzymes metabolize catecholamines?
catecholamines: Ne, E, Dopamine

catecho-o-methyl transferase and then/or MAO (monoamine oxidase)
How are catecholamines synthesized?
yrosine to dopa to dopamine to NE (via dopamine B hydroxylase--DBH) to Epi (via phenylethalnolamine-N-methyltransferase)
How does DBH get released?
released with NE and contents w/in vescicle at the adernergic terminal
is epinephrine membrane bound or free?
epi is free
Name the cholinoceptors.
muscarinic M1,2,3 and nicotinic Nm, Nn
Where are each of the muscarinic receptors found?
M1 in the CNS neurons and some PRE-synaptic sites

M2: mycardium, smooth mm, some PRE-synaptic sites

M3: exocrine glands, vessels (smooth mm and endothelium)
Where are the nicotinic receptors found?
Nn: POST ganglionic neurons some presynaptic cholinergic terminals

Nm: skeletal mm neuromuscular end plates
What types of ligand binding are used in the muscarinic receptors?
M1 and M3 use IP3 and DAG increasing intracellular Ca

M2 opens K channels, inhibiting adenylyl cyclase leading to hyperpolarization
What types of ligand binding do nicotinic receptors use?
both Nn and Nm use opening of Na/K channels causing depolarization
What are the adrenoceptors?
Alpha 1,2

beta 1,2,3
Where are alpha 1 receptors found? alpha 2?
alpha 1: post synaptic effector cells, especially smooth mm

alpha 2: presynaptic adrenergic nerve terminals, platelets, lipocytes
Where are Beta 1 receptors found?
Beta 1 found on POST synaptic effector cells esp in HEART, lipocytes, brain

presynaptic adrenergic and cholinergic n terminals.
Where are beta 2 receptors found?
POSTsynaptic effector cells esp SMOOTH mm and cardiac mm
Where are beta 3 receptors found?
POSTsynaptic effector cells. esp lipocytes
What are the dopamine receptors?
D1, (DA1), D5 found in the brain effector tissues esp smooth mm of the renal vascular bed.

D2 (DA2) brain effector tissues esp smooth mm

D3 brain

D4 brain/CV
What is the result of ligand binding in the alpha 1 and 2 adrenoceptors?
alpha 1: fomationof IP3 and DAG increased intracellular ca

alpha 2: inhibition of adenylyl cyclase, decreased cAMP
What is the result of ligand binding in the beta adrenoceptors?
b1,2,3: stimulaton of adenylyl cyclase, increased cAMP

Note: b2 also activates cardiac Gi under some conditions
What is the result of ligand binding in the dopamine receptors?
for D1, (DA1), and D5 = stimulation of adenylyl cyclase and increased cAMP

for all others inhibiton of adenylyl cyclase
Where do sympathetic and PS tone predominate?
symp tone: in the blood vessels

PS in the heart, eyes, GI, urinary bladder
What does miosis mean? Mydriasis?

mydrasis--dilate the pupil
What are teh effects of a chloinergic or adrenergic blocking agent (antagonist) dependent on?
autonomic innervation to the organ and degree of sym or PS tone
In the eye what effect do beta blockers, muscarinic agonists and antagonists have?
beta blockers: DECREASE aq humor

muscarinic agonists: contract circular fibers and CONSTRICT the pupil. relax lens for NEAR vision, improve drainage

Muscarinic antagonists: DILATE pupil with radial fibers, occlude canal of Schlemm, increase IOP--glaucoma
Which receptors are found in the eye?
M3 in the smooth mm: circular mm and radial mm.

B in ciliary epithelium (which is why if blocked decrease aq humor)

alpha 1 postsynaptic eye mm
If the PS innervation of the eye is stimulated what will happen? What if it is blocked?
stimulated then the circular mm will contract and miosis occurs. blocked mydrasis
If the sympathetic innervation of the eye is stimulated what will happen? What if it is blocked?
symp to radial smooth mm--stimulated dilate eye; mydrasis and blocked miosis
What innervates the stiated fibers of the external sphincter? The bladder body?

What receptor?
external sphincter by the somatic motor fibers

urinary bladder body by the ANS

What happens in the bladder upon PS stimulation? Inhibition of PS?
contract detrussor, relax trigone and sphincter and micturate

inhibition--urinary retention by alpha 1 and beta 2
What receptor is in the detrusor? The trigone?
detrusor: beta 2

tribone: alpha 1
What happens upon ps stimulation of the GI tract? Upon sympathetic stimulation? Name receptors.
increase GI motility and relax sphincters; increase secretion of exocrine glands; increase peristalsis and defication. M3 receptor

Sympathetic: relax GI (Beta 2 ) and contract sphincter: (alpha 1). leads to constipation
What receptors are involved in sympathetic innervation of the SA and AV nodes, atria and ventricles?

What happens on stimulation? inhibition?
Beta 1

on stimulation increase heart rate, contractility and conduction.

Inhibition of sympathetic: decrease heart rate etc.
what happens when PS of heart is stimulated?
decrease heart rate etc
What symp. receptor predominates in the arteroles and veins of the CV system? What happens upon stimulation? inhibition?
alpha 1

stimulation of symp: vasoconstriction increase pressure

inhibition: dilation
What PS receptor predominates in the arteroles and veins of the CV system? What happens upon stimulation? inhibition?
most blood vessels are not innervated, but some muscarinic receptors are present: M3

Where are baroreceptors found?
In the carotid sinus and arotic arch.

determine indirect CV effects of autonomic drugs
What do basoreceptor reflexes promote?
increase in vagal activity

decrease sympathetic activity: decrease heart rate and total peripheral resistance (TPR)

increase vasodilation
If a drug directly lowers BP what result will this have in teh baroreceptors?
decreased firing of baroreceptors and promotion of decreased vagal activity AND increased symp activity. increase total peripheral resistance w/ a tendency for BP to rise again
Do most vessels receive PS innervation?
No, BUT they have muscarinic cholinergic receptors present.
What is the degree of vasoconstriction or dilation dependent on?
sympathetic tone increase = vasoconstriction increase TPR

decrease symp tone leads to vasodilation decreased TPR
Name a drug that acts to alter autonomic responses