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2, 6. Introduction to the Autonomic Nervous System
Ram Reddy
49
Biology
Graduate
09/19/2011

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Term
Parasympathetic response in eye
Definition
Post synaptic neuron->acetylcholine->M3 muscarinic receptor on constrictor muscle->eye constricts
Term
Sympathetic response in eye
Definition
Post synaptic neuron->Norepinephrine/epinephrine->alpha 1 receptor on dilator muscle (radial/circular muscle)->eye dilates
Term
Consequences of sympathetic response
Definition
1. Cardiac output up
2. Respiration up
3. Glomular Filtration Rate (GFR) down
4. Immune system activity down
5. Cell division and apoptosis down.
6. Catabolism up
Term
Consequences of parasympathetic response
Definition
1. Cardiac output down
2. Respiration down
3. Glomular Filtration Rate (GFR) up
4. Immune system activity up
5. Cell division and apoptosis up.
7. Anabolism up
Term
M1, M3, M5 receptors
Definition
Gq mechanism, results in IP3 2nd messenger and increase in Ca levels(EPSP). M3 receptors most numerous.
Term
Nicotinic receptors
Definition
Na, K antiporter, EPSP. Neuronal ganglia have nicotinic receptors.
Term
M2,M4 receptors
Definition
Gi mechanism, opens K channels, closes Ca and Na channels, and downregulates cAMP. M2 receptors most numerous.
Term
Alpha 1 receptor
Definition
Gq mechanism, results in IP3 2nd messenger and increase in Ca levels(EPSP)
Term
Alpha 2 receptors
Definition
Gi mechanism, opens K channels, closes Ca and Na channels, and downregulates cAMP.
Term
Beta 1,2,3 receptors
Definition
Gs mechanism, results in increase in cAMP, activates PKA. PKA opens Ca and Na channels, closes K channels. Results in EPSP.
Term
Micturation center
Definition
Found in midbrain of brain stem. When bladder is full, stretch receptors signal to micuration center. Parasympathetic neuron then releases acetylcholine on bladder muscle, causes contraction of bladder and relaxation of sphincter.
Term
Heartbeat modulation by autonomics. Buttload of information!
Definition
Heart has stretch receptors (Baroreceptors) that sense BP. In high BP, pseudounipolar neurons relay message to brain stem. A parasympathetic neuron then releases acetylcholine onto SA node M2 receptors in heart, creates Gi response and increases K current in GIRK channels, hyperpolarizes cells, decreases HR (reflex bradycardia) In low BP situations, a sympathetic neuron releases NE and E on beta 1 receptors to increase heart rate through IPSP Gs mechanism in funny channels. Chemoreceptors on SA node also modulate heartbeat.
Term
Exception in autonomic neurotransmitters
Definition
Sympathetic neurons to the sweat glands use acetylcholine.
Term
Parasympathetic receptors
Definition
Nicotinic and Muscarinic receptors
Term
Sympathetic receptors
Definition
Alpha 1 and 2 receptors
Beta 1,2,3 receptors
All G protein responses.
Term
Cholinergic receptors
Definition
Uses nicotinic receptors in ganglia for fast response.
Uses all muscarinic receptors (M1, M2, M3, M4, M5)
Term
Acetylcholine nerve terminal sequence
Definition
1. Acetylcholine synthesized.
2. Unstable acetylcholine is protected in a vesicle.
3. Upon Ca depolarization, Ach is released into synaptic cleft.
4. Binds to receptor in post synaptic cell.
5. Ach then degraded by acetylcholine esterase.
6. Choline taken up by neuron.
Term
Receptors in heart muscle
Definition
M2 (uncommon in ventricles, affect HR) and Beta 1 (Found everywhere, affects both HR and ventricle contraction).
Term
Receptors in blood vessels
Definition
Only sympathetic response. Have Alpha 1, M3 (for contraction) and Beta 2 receptors (for dilation).
Term
Pancreas receptors
Definition
Alpha 2 receptors in pancreas to inhibit insulin release for higher blood sugar (sympathetic response).
Term
Adrenergic nerve terminal actions
Definition
1. Tyrosine hydroxylation eventually creates Dopamine (DA), NE, and EPI.
2. NE and EPI packaged into storage vesicles.
3. Release of NE upon Ca depolarization.
4. Binding to receptor.
5. Reuptake of NE into pre-synaptic neuron.
6. NE metabolized by COMT and MAO.
Term
Synthesis of catecholamines
Definition
Tyrosine->L-Dopa->Dopamine->NE->EPI

Tyosine hydroxylase is rate limiting step.
EPI only made in adrenal medulla (80% EPI/20%NE) in periphery.
Term
Catechol group
Definition
1,2 Dihydroxybenzene.
Term
MAO
Definition
Mono amine oxidase. Oxidizes NE.
Term
COMT
Definition
Catecholamine Methyl Transferase. Methylates NE.
Term
Dopamine
Definition

Big role in CNS, not in periphery. Metabolized by MAO and COMT into HVA. Too little=Parkinson's Too much=Schizophrenia

Used in hospitals to maintain adequate blood flow to kidneys during trauma.

Term
VMA
Definition
Vanillyl Mandelic Acid.
Results from breakdown of NE and EPI by COMT and MAO.
Excreted in urine, used as a test for Pheochromocytoma (adrenal medulla cancer).
Term
Receptors in lungs
Definition
Has M3 receptors (parasympathetic) and B2 (sympathetic) receptors.
Tidal Volume (TV, more important) and Respiratory Rate (RR) affected.
Term
-tropium
Definition
Class of drugs that block M3 receptors in lungs, leads to bronchodilation. Frequently paired with B2 agonist for increased effect.
Term
-terol
Definition
Class of drugs that activate Beta 2 receptors in lung, creates bronchodilation. Frequently paired with M3 antagonists.
Term
Stroke Volume (SV)
Definition
Amount of blood ejected per ventrical contraction.
Equals End Diastolic Volume (EDV)-End Systolic Volume (ESV)
Term
Ejection Fraction (EF)
Definition
SV/EDV
Term
Cardiac Output
Definition
SV x HR
Term
Components of heart
Definition
1. Fibrous skeletal component with one way valves
2. 4 chambers
3. Electrical component
Term
Sequence of electrical components of heart
Definition
SA Node->AV node->Bundle of His->Branches->Purkinje Fibers
Term
Intrinsic HR of heart
Definition
~100-110 bpm, parasympathetic imput keeps it lower in normal patient.
Term
Mechanism of parasympathetic imput to heart
Definition
1. Ach binds to M2 receptors in SA node. 2. Gi mechanism initiated, cAMP downregulated. 3. Low cAMP opens GIRK channels and downregulates funny channels. 4. Creates IPSP, Ca and Na levels also down due to downregulation of funny channels.
Term
Parasympathetic mechanism in lungs
Definition
1. Ach binds to M3 receptors in lungs.
2. Causes EPSP through Gq mechanism, constrict bronchioles.
Term
Autonomic response in sweat glands
Definition
Only sympathetic imput using Ach on M3 receptors (exception).
Causes GI fluid loss, profuse sweating, and diarrhea.
Term
Action potential in SA node cells
Definition
SA node cells initially depolarize to threshold using funny channels, which act like nicotinic receptors (Na in, K out). Funny channels are activated by hyperpolarization or by high cAMP levels. Once theshold is reached, Ca channels open to depolarize the SA cell, but with no long depolarization from Ca L channels. The cell repolarizes by opening GIRK (K) channels.
Term
Sympathetic mechanism in heart
Definition
NE binds to beta 1 receptors which activate HCN (funny channels) through cAMP increase (Gs mechanism). Funny channels then initiate action potential.
Results in increase of HR, contractility, conduction velocity, and Ca reuptake in SR, with a shorter diastolic phase.
Term
Blood vessel autonomic regulation
Definition
M3 and alpha 1 (EPI binds) receptors cause contraction.
Beta 2 (EPI binds) and NO cause relaxation.
Term
Tone
Definition
Amount on overlap between actin and myosin in muscles. There is always some sympathetic innervation to keep muscle toned and BP sufficiently high, unless anesthesia is administered. Without muscle tone, blood vessels will dilate and BP will fall.
Term
Factors increasing Renal Blood Flow
Definition
Dopamine, Prostaglandins, ANP/ANF, Bradykinin
Term
Factors decreasing Renal Blood Flow (RBF)
Definition
NE, EPI, Renin, Angiotensin II
Term
Pathway for vasoconstriction
Definition
Angiotensinogen->Angiotensin I (by Renin)->Angiotensin II (by ACE)-> Aldosterone

NE and EPI bind to beta 1 receptors in kidney to stimulate Renin production.
Term
Aldosterone
Definition
Production stimulated by Angiotensin II. Promotes Na resorption by giving up K. Sympathetic response, can tell by high K levels in urine.
Term
Parasympathetic control of bladder
Definition
Parasympathetic mechanism for detrusor muscle:
Ach->M3->IP3->Ca->contraction
Parasympathetic control of bladder sphincter:
Ach->M2->K channels open-> relaxation
Term
Sympathetic control of bladder
Definition
Sympathetic control of Bladder detrusor muscle:
NE/EPI->B2->cAMP->PKA->MLC Phosphatase->relaxation
Sympathetic control of sphincter:NE->Alpha 1->M3->IP3->Ca->contraction
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