2-1: Anatomy - 1/6: Autonomic Transmitters & Receptors I, Ii

Front 1

What class of neurons are employed by the somatic nervous system?

Where are their ganglia located?

Effectors organs?

Receptor type?

Back 1

Somatic NS:
Cholinergic MN's (secrete ACh)

Found in Brain (cranial nerve nuclei) and SC (ventral horn)

Effect NICOTINIC receptors on skeletal muscle

Front 2

What class of neurons are employed by the sympathetic nervous system?

Where are their cell bodies located?

Effectors organs?

Receptor type?

Back 2

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)

Front 3

What class of neurons are employed by the parasympathetic nervous system?

Where are their cell bodies located?

Effectors organs?

Receptor type?

Back 3

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)

Front 4

What class of neurons are employed by the adrenal medullary?

Where are their cell bodies located?

Effectors organs?

Receptor type?

Back 4

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

Front 5

How do the preganglionic and postganglionic neurons of the peripheral nervous system differ developmentally?

Back 5

Pregang (including motorneurons in somatic NS) develop from neuroepithelium

Postgang develop from NCC

Front 6

What are chromaffin cells? How does their development contribute to their function?

Back 6

Cells derived from neuroblasts that make up cells of adrenal medulla; don't develop neural processes so just dump NE and E into circulation

Front 7

All preganglionic neurons of the ANS are ________________

Back 7

cholinergic

Front 8

All postganglionic neurons of the ANS have ___________ receptors

Back 8

cholinoreceptors (nicotinic)

Front 9

Postganglionic neurons may be ____________ or ______________

Back 9

adrenergic or nicotinic

Front 10

MOST postganglionic parasympathetic neurons are ___________

Back 10

cholinergic

Front 11

Postganglionic sympathetic neurons are mostly __________, with the exception of the ___________ neurons that innervate ______________

Back 11

adrenergic, except cholinergic neurons that innervate sweat glands

Front 12

Where are nicotinic receptors located?

Back 12

Motor end plates (skeletal muscle)
All post-ganglionic autonomic neurons
Chromaffin cells (adrenal medulla)

Front 13

How are receptors of the somatic and autonomic systems similar? Different?

Back 13

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

Front 14

What is the mechanism of action of nicotinic receptors?

Back 14

ACh binds receptors, opens Na+/K+ channels, results in AP

Front 15

Where are muscarinic receptors located?

Back 15

All effector organs of parasymp NS, and sweat glands (symp)

Front 16

What are the subtypes of muscarinic receptors? What is their mechanism of action?

Back 16

M1, M2, M3

Mech: similar to adrenoreceptors; mediated by G prots

Front 17

Which receptors employ G proteins? How do these receptors mediate different effects if they're linked to G proteins?

Back 17

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

Front 18

What second-messenger do a1 receptor G proteins employ?

Back 18

IP3

Front 19

What second-messenger do B1/B2 receptor G proteins employ?

Back 19

cAMP

Front 20

Where are a1 receptors found? Effect?

Back 20

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

Front 21

Where are a2 receptors found? Effect?

Back 21

a2 receptors:
walls of GI tract

Effect: RELAXATION of gut smooth muscle

Front 22

Where are B1 receptors found? Effect?

Back 22

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

Front 23

Where are B2 receptors found?

Back 23

B2 receptors:

Vascular smooth muscle of:
Skeletal muscle
Walls of GI tract and bladder
Bronchioles

Effect: relaxation of smooth muscle (DILATION)

Front 24

What is the effect of B1 receptor activation at the SA node?

Back 24

Increased rate of spontaneous depolarization, increased heart rate

Front 25

What is the effect of B1 receptor activation at the AV node?

Back 25

Increased speed of propagation through the AV node

Front 26

What is the effect of B1 receptor activation at the ventricular myocardium?

Back 26

Increased contractility

Front 27

What is the overall effect of B1 receptors in the heart? What is the effect of B1-blockers?

Back 27

Increase cardiac output (important for fight or flight)

B1-blockers would decrease heart rate and output

Front 28

Beginning with dopamine, describe the steps in the production of catecholamines.

What compound do catecholamines all contain in their structure?

Back 28

Dopamine-->NE-->Epi

All have catechol (o-dihydroxybenzene)

Front 29

For a1 receptors:

Compare potency of NE to Epi
Compare sensitivity to circulating catecholamines (relative to B receptors)

Back 29

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

Front 30

For B1 receptors:

Compare potency of NE to Epi
Compare sensitivity to circulating catecholamines (relative to a1 receptors)

Back 30

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

Front 31

For B2 receptors:

Compare potency of NE to Epi
Compare sensitivity to circulating catecholamines (relative to a1 receptors)

Back 31

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

Front 32

In the parasympathetic NS, effector organs only have ______ receptors

Back 32

Parasymp: Muscarinic

But there are diff receptor types with diff mechanisms of action

Front 33

In the sympathetic NS, effector organs have ______ receptors

Back 33

Sympathetic: adrenoreceptors (4 types) and muscarinic receptors (of THERMOREGULATORY sweat glands)

Front 34

In general, a and a1 receptors cause ________ of smooth muscle.

Back 34

Contraction

Front 35

In general, B1 receptors ______________ metabolic and cardiac functions

Back 35

Increases

Front 36

In general, B2 receptors cause _________ of smooth muscle.

Back 36

Relaxation

Front 37

Parasympathetic vs Sympathetic. Which dominates where?

Back 37

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),

Front 38

Hexamethonium

Back 38

Antiocholinergic Ganglion Blockers

Front 39

What is the effect of blocking all nicotinic receptors in the ANS?

Back 39

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

Front 40

Muscarinic agonists: general category, effect

Back 40

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)

Front 41

Acetylcholinesterase inhibitors: general category, effects

Back 41

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)

Front 42

Muscarinic-Blockers: general category

Back 42

Anticholinergic = cholinergic antagonists = adrenergics = sympatheticomimetics

1) Atropine (M blocker) is prototype, most are anti-muscarinic

Front 43

Mecamylamine

Back 43

Antiocholinergic Ganglion Blocker

Front 44

Alpha-1 blockers: general category, effects

Back 44

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)

Front 45

Beta-antagonists: drug category, effects

Back 45

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)

Front 46

Muscarinic Antagonists: drug category, effects

Back 46

Spiriva, anticholinergic (blocks M receptors) used to treat COPD

Effects: Bronchodilator, relaxes bronchial smooth muscle, reduces mucous secretions

Side Effects: Xerostomia (dry mouth)

Front 47

Nicotinic Antagonists: drug category, effects

Back 47

2) Anti nicotinic: non-depolarizing skeletal muscle relaxants (related to curare) used for surgery (atacurium, pancuronium)

Front 48

B1 Agonists: drug category, uses, side effects

Back 48

b1 agonists (dobutamine): used for acute heart failure (effect: increases cardiac output)

Front 49

B2 agonists: drug category, uses, side effects

Back 49

b2 agonists (albuterol): treats asthma; effect: excites B2 receptors, induces bronchodilation (much shorter acting than Spiriva)