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49 Cards in this Set
- Front
- Back
What class of neurons are employed by the somatic nervous system?
Where are their ganglia located? Effectors organs? Receptor type? |
Somatic NS:
Cholinergic MN's (secrete ACh) Found in Brain (cranial nerve nuclei) and SC (ventral horn) Effect NICOTINIC receptors on skeletal muscle |
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What class of neurons are employed by the sympathetic nervous system?
Where are their cell bodies located? Effectors organs? Receptor type? |
Sympathetic:
Preganglionic: Cholinergic onto Nicotinic Post Ganglionic Postganglionic: Cholinergic (onto MUSCARINIC receptors of sweat glands) Adrinergic (Norepi) onto a1, a2, B1, B2 (adrenoreceptors) of smooth muscle, cardiac muscle, glands Found in lateral horn gray matter of T1-L2/3 (THORACOLUMBAR) |
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What class of neurons are employed by the parasympathetic nervous system?
Where are their cell bodies located? Effectors organs? Receptor type? |
Parasympathetic:
Preganglionic: Cholinergic onto NICOTINIC Postganglionic: Cholinergic onto MUSCARINIC of smooth/cardiac muscle, glands Found in CN III, VII, IX, X; S2-S4 (craniosacral system) |
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What class of neurons are employed by the adrenal medullary?
Where are their cell bodies located? Effectors organs? Receptor type? |
Adrenal Medulla:
Preganglionic: Cholinergic onto NICOTINIC of adrenal medulla Adrenal Medulla releases 80% epi, 20% norepi to CIRCULATION Epi, NE bind a1, a2, B1, B2 of smooth/cardiac muscle, glands Located in sympathetic NC, greater splanchnic nerves, T5-T9/10 |
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How do the preganglionic and postganglionic neurons of the peripheral nervous system differ developmentally?
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Pregang (including motorneurons in somatic NS) develop from neuroepithelium
Postgang develop from NCC |
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What are chromaffin cells? How does their development contribute to their function?
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Cells derived from neuroblasts that make up cells of adrenal medulla; don't develop neural processes so just dump NE and E into circulation
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All preganglionic neurons of the ANS are ________________
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cholinergic
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All postganglionic neurons of the ANS have ___________ receptors
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cholinoreceptors (nicotinic)
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Postganglionic neurons may be ____________ or ______________
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adrenergic or nicotinic
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MOST postganglionic parasympathetic neurons are ___________
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cholinergic
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Postganglionic sympathetic neurons are mostly __________, with the exception of the ___________ neurons that innervate ______________
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adrenergic, except cholinergic neurons that innervate sweat glands
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Where are nicotinic receptors located?
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Motor end plates (skeletal muscle)
All post-ganglionic autonomic neurons Chromaffin cells (adrenal medulla) |
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How are receptors of the somatic and autonomic systems similar? Different?
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Receptors in somatic and autonomic systems are
Activated by Ach, nicotine, and carbachol (agonists) Blocked by curare (antagonist) BUT Some compounds (hexamethonium) block ganglia but not motor end plates |
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What is the mechanism of action of nicotinic receptors?
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ACh binds receptors, opens Na+/K+ channels, results in AP
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Where are muscarinic receptors located?
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All effector organs of parasymp NS, and sweat glands (symp)
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What are the subtypes of muscarinic receptors? What is their mechanism of action?
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M1, M2, M3
Mech: similar to adrenoreceptors; mediated by G prots |
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Which receptors employ G proteins? How do these receptors mediate different effects if they're linked to G proteins?
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All autonomic receptors (muscarinig and adrenergic) are linked to G proteins
Different receptor types (a1, b1/b2,etc) are linked to different G proteins so their activation may mediate different effects |
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What second-messenger do a1 receptor G proteins employ?
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IP3
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What second-messenger do B1/B2 receptor G proteins employ?
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cAMP
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Where are a1 receptors found? Effect?
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a1 receptors found in
-Vascular smooth muscle of: Skin Skeletal muscle Splanchnic region -sphincters of GI tract and bladder -radial muscles of iris (dilator pupilae) Effect: contraction of smooth muscle |
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Where are a2 receptors found? Effect?
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a2 receptors:
walls of GI tract Effect: RELAXATION of gut smooth muscle |
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Where are B1 receptors found? Effect?
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B1 receptors:
SA and AV node Ventricular myocardium Salivary glands Adipose tissue Kidney Effect: increased heart rate, increased conduction velocity, increased salivation, increased lipolysis increased renin secretion |
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Where are B2 receptors found?
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B2 receptors:
Vascular smooth muscle of: Skeletal muscle Walls of GI tract and bladder Bronchioles Effect: relaxation of smooth muscle (DILATION) |
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What is the effect of B1 receptor activation at the SA node?
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Increased rate of spontaneous depolarization, increased heart rate
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What is the effect of B1 receptor activation at the AV node?
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Increased speed of propagation through the AV node
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What is the effect of B1 receptor activation at the ventricular myocardium?
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Increased contractility
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What is the overall effect of B1 receptors in the heart? What is the effect of B1-blockers?
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Increase cardiac output (important for fight or flight)
B1-blockers would decrease heart rate and output |
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Beginning with dopamine, describe the steps in the production of catecholamines.
What compound do catecholamines all contain in their structure? |
Dopamine-->NE-->Epi
All have catechol (o-dihydroxybenzene) |
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For a1 receptors:
Compare potency of NE to Epi Compare sensitivity to circulating catecholamines (relative to B receptors) |
For a1:
NE and Epi have same potency Compared to B receptors, a1 receptors are relatively insensitive to circulating catecholamines ([ ] too low) THUS a1 receptors are not activated by adrenals (release catecholamines into circulation) a1 receptors are only activated by postganglionic sympathetic neurons |
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For B1 receptors:
Compare potency of NE to Epi Compare sensitivity to circulating catecholamines (relative to a1 receptors) |
For B1 receptors:
Ne and Epi have same potency B1 receptors are more sensitive to Epi and NE than a1 receptors THUS B1 receptors excited from release of NE from postgang symp nbeurons and/or by release of Epi and NE from adrenal medulla |
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For B2 receptors:
Compare potency of NE to Epi Compare sensitivity to circulating catecholamines (relative to a1 receptors) |
For B2 receptors:
Epi is more potent than NE More sensitive to circulating catecholamines than a1: B2 receptors ARE NOT innervated, they're only excited by Epi from adrenal medulla |
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In the parasympathetic NS, effector organs only have ______ receptors
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Parasymp: Muscarinic
But there are diff receptor types with diff mechanisms of action |
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In the sympathetic NS, effector organs have ______ receptors
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Sympathetic: adrenoreceptors (4 types) and muscarinic receptors (of THERMOREGULATORY sweat glands)
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In general, a and a1 receptors cause ________ of smooth muscle.
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Contraction
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In general, B1 receptors ______________ metabolic and cardiac functions
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Increases
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In general, B2 receptors cause _________ of smooth muscle.
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Relaxation
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Parasympathetic vs Sympathetic. Which dominates where?
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Parasympathetic is mostly in charge
Sympathetic dominates where there's no parasympathetic input: Vasc Smooth Muscle of splanchnic skin, skeletal muscle, radial muscle of the iris, sweat glands (thermoregulatory and stress), |
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Hexamethonium
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Antiocholinergic Ganglion Blockers
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What is the effect of blocking all nicotinic receptors in the ANS?
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Block nicotinic receptors-->blocks all autonomic input to autonomic organs
It'd be the same as antagonizing the dominant system (or stimulating the non-dominant system) Ex: No erections, no ejaculations, increased heart rate |
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Muscarinic agonists: general category, effect
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Bethanechol (M agonist): treats urinary retention, stimulates bowel movement (but can cause asthma, coronary insufficiency, peptic ulcers (increased secretions), intestinal obstruction
Cholinergic = cholinergic agonists = anti-adrenergics = parasympatheticometics Direct-acting cholinergics directly stimulate receptors ACh (affects everything) |
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Acetylcholinesterase inhibitors: general category, effects
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Indirectly agonize cholinergic effects by inhibiting AChesterase, or by inhibiting Symp NS:
1) Physostigmine: inhibits acetylcholinesterase; used to treat myasthenia gravis (autoimmune dz, body produces Ab's against N receptors) Effects: increased [ACh] at junction (fewer receptors to bind so they'll be open longer) |
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Muscarinic-Blockers: general category
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Anticholinergic = cholinergic antagonists = adrenergics = sympatheticomimetics
1) Atropine (M blocker) is prototype, most are anti-muscarinic |
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Mecamylamine
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Antiocholinergic Ganglion Blocker
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Alpha-1 blockers: general category, effects
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Indirect cholinergic
2) a1 blockers (alpha-antagonists) used to treat hypertension, but not the drug of choice Ex: Prazosin--a1 blocker used to treat Raynaud's (effect is vasodilation of peripheral vasculature) |
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Beta-antagonists: drug category, effects
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Indirect cholinergic
3) Beta blockers (beta antagonists) widely used to treat HTN, often end in -lol: ex: propanolol, metaprolol; effect is to decrease cardiac output but can cause HYPOtension Can also be used to inhibit tachycardia, for social/performance anxiety (decreases tremors) |
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Muscarinic Antagonists: drug category, effects
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Spiriva, anticholinergic (blocks M receptors) used to treat COPD
Effects: Bronchodilator, relaxes bronchial smooth muscle, reduces mucous secretions Side Effects: Xerostomia (dry mouth) |
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Nicotinic Antagonists: drug category, effects
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2) Anti nicotinic: non-depolarizing skeletal muscle relaxants (related to curare) used for surgery (atacurium, pancuronium)
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B1 Agonists: drug category, uses, side effects
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b1 agonists (dobutamine): used for acute heart failure (effect: increases cardiac output)
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B2 agonists: drug category, uses, side effects
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b2 agonists (albuterol): treats asthma; effect: excites B2 receptors, induces bronchodilation (much shorter acting than Spiriva)
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