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59 Cards in this Set
- Front
- Back
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What are the two major subdivisions of the peripheral nervous system?
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somatic and autonomic
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What does the somatic nervous system control?
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skeletal mm
voluntary |
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Is the ANS voluntary or involuntary?
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involuntary
AKA visceral, vegetative, involuntary nervous system |
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What are the efferent portions of the ANS?
What type of nerves are the efferents? |
sympathetic -- thoracolumbar
parasympathetic--craniosacral efferents are peripheral and motor |
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Where do the sympathetics and parasympathetics originate?
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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
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What is the response of the sympathetic nervous system?
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dilated pupils
broncho dilation and increased pulmonary secretions increased heart rate and contractility gi motility and secretions decrease and urine is retained |
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What is the parasympathetic response?
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decreased heart beat, increased secretions, bronchioles constricted, defication, urination, erection. pupils constrict
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Describe the length of the pre and post ganglion in both parasympathetic and sympathetic nervous systems.
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Sympathetic: short pre gangion and long post
PS: long pre and short post |
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How many synapses are found in a skeletal motor axon?
Autonomic S and PS? |
one
both have 2 neuron chain |
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What type of receptor are all autonomic preganglions?
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cholinergic
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What type of neurons are ALL parasympathetic postganglionic neurons?
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cholinergic
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What type of neurons are MOST sympathetic POSTganglionic neurons?
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adernergic--mainly cardiac smooth mm, glands (except for sweat), nerve terminals
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What is the adrenal medulla?
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modified sympathetic ganglion
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What types of cells are "effectors"?
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cardiac, smooth mm, gland cells, sometimes endothelial and nerve terminals
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What are the inhibitors of Ach release (Cholinergic)? What do they specifically inhibit?
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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 |
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How can Ach enter the nerve terminal?
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by a sodium dependent carrier
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What happens to Ach after it enters the synapse?
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1. recycled
2. degraded 3. add on aurto receptor and fxn as negative feedback |
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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 |
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What does MAO do?
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MAO will breakdown NE UNLESS it is in a vescicle
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What are the uptake mechanisms in the noradrenergic junciton?
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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) |
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What enzymes metabolize catecholamines?
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catecholamines: Ne, E, Dopamine
catecho-o-methyl transferase and then/or MAO (monoamine oxidase) |
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How are catecholamines synthesized?
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yrosine to dopa to dopamine to NE (via dopamine B hydroxylase--DBH) to Epi (via phenylethalnolamine-N-methyltransferase)
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How does DBH get released?
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released with NE and contents w/in vescicle at the adernergic terminal
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is epinephrine membrane bound or free?
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epi is free
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Name the cholinoceptors.
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muscarinic M1,2,3 and nicotinic Nm, Nn
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Where are each of the muscarinic receptors found?
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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) |
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Where are the nicotinic receptors found?
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Nn: POST ganglionic neurons some presynaptic cholinergic terminals
Nm: skeletal mm neuromuscular end plates |
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What types of ligand binding are used in the muscarinic receptors?
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M1 and M3 use IP3 and DAG increasing intracellular Ca
M2 opens K channels, inhibiting adenylyl cyclase leading to hyperpolarization |
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What types of ligand binding do nicotinic receptors use?
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both Nn and Nm use opening of Na/K channels causing depolarization
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What are the adrenoceptors?
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Alpha 1,2
beta 1,2,3 |
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Where are alpha 1 receptors found? alpha 2?
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alpha 1: post synaptic effector cells, especially smooth mm
alpha 2: presynaptic adrenergic nerve terminals, platelets, lipocytes |
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Where are Beta 1 receptors found?
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Beta 1 found on POST synaptic effector cells esp in HEART, lipocytes, brain
presynaptic adrenergic and cholinergic n terminals. |
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Where are beta 2 receptors found?
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POSTsynaptic effector cells esp SMOOTH mm and cardiac mm
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Where are beta 3 receptors found?
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POSTsynaptic effector cells. esp lipocytes
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What are the dopamine receptors?
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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 |
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What is the result of ligand binding in the alpha 1 and 2 adrenoceptors?
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alpha 1: fomationof IP3 and DAG increased intracellular ca
alpha 2: inhibition of adenylyl cyclase, decreased cAMP |
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What is the result of ligand binding in the beta adrenoceptors?
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b1,2,3: stimulaton of adenylyl cyclase, increased cAMP
Note: b2 also activates cardiac Gi under some conditions |
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What is the result of ligand binding in the dopamine receptors?
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for D1, (DA1), and D5 = stimulation of adenylyl cyclase and increased cAMP
for all others inhibiton of adenylyl cyclase |
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Where do sympathetic and PS tone predominate?
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symp tone: in the blood vessels
PS in the heart, eyes, GI, urinary bladder |
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What does miosis mean? Mydriasis?
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miosis--constrict
mydrasis--dilate the pupil |
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What are teh effects of a chloinergic or adrenergic blocking agent (antagonist) dependent on?
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autonomic innervation to the organ and degree of sym or PS tone
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In the eye what effect do beta blockers, muscarinic agonists and antagonists have?
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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 |
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Which receptors are found in the eye?
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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 |
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If the PS innervation of the eye is stimulated what will happen? What if it is blocked?
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stimulated then the circular mm will contract and miosis occurs. blocked mydrasis
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If the sympathetic innervation of the eye is stimulated what will happen? What if it is blocked?
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symp to radial smooth mm--stimulated dilate eye; mydrasis and blocked miosis
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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 M3 |
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What happens in the bladder upon PS stimulation? Inhibition of PS?
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contract detrussor, relax trigone and sphincter and micturate
inhibition--urinary retention by alpha 1 and beta 2 |
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What receptor is in the detrusor? The trigone?
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detrusor: beta 2
tribone: alpha 1 |
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What happens upon ps stimulation of the GI tract? Upon sympathetic stimulation? Name receptors.
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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 |
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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. |
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what happens when PS of heart is stimulated?
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decrease heart rate etc
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What symp. receptor predominates in the arteroles and veins of the CV system? What happens upon stimulation? inhibition?
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alpha 1
stimulation of symp: vasoconstriction increase pressure inhibition: dilation |
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What PS receptor predominates in the arteroles and veins of the CV system? What happens upon stimulation? inhibition?
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most blood vessels are not innervated, but some muscarinic receptors are present: M3
BP = CO x TPR |
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Where are baroreceptors found?
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In the carotid sinus and arotic arch.
determine indirect CV effects of autonomic drugs |
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What do basoreceptor reflexes promote?
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increase in vagal activity
decrease sympathetic activity: decrease heart rate and total peripheral resistance (TPR) increase vasodilation |
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If a drug directly lowers BP what result will this have in teh baroreceptors?
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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
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Do most vessels receive PS innervation?
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No, BUT they have muscarinic cholinergic receptors present.
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What is the degree of vasoconstriction or dilation dependent on?
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sympathetic tone increase = vasoconstriction increase TPR
decrease symp tone leads to vasodilation decreased TPR |
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Name a drug that acts to alter autonomic responses
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clondine
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