Fox Chapter 9 (plus selections from Chapters 7, 8, 14 & 20)

Autonomic n.s.

It's a motor system


Fig. 8.28
Fig. 9.3
motor system for smooth muscle and glands
contrasted with somatic system innervating striated (skeletal) muscle
Autonomic has preganglionic and postganglionic output

Fig. 7.3
Another figure to show the same thing

Parasympathetic and sympathetic

TRANSPARENCY (From an intro book)
Parasympathetic = "rest and digest"
Sympathetic = "fight or flight"

Fig. 9.5 [Fox's version of this same classic figure]
Parasympathetic, cranio-sacral, ACh (nicotinic and muscarinic), ganglion near target
Sympathetic, thoraco-lumbar, ACh (nicotinic) then NE, ganglion near spinal cord

Acetylcholine and Norepinephrine

Fig. 9.7
(same material on next two lines)
Parasympathetic, cranio-sacral, ACh (nicotinic and muscarinic), ganglion near target
Sympathetic, thoraco-lumbar, ACh (nicotinic) then NE, ganglion near spinal cord

Fig. 9.10
(same material on next two lines)
Parasympathetic, cranio-sacral, ACh (nicotinic and muscarinic), ganglion near target
Sympathetic, thoraco-lumbar, ACh (nicotinic) then NE, ganglion near spinal cord

For NE (adrenergic), all receptors are G-protein-coupled-receptors
Alpha (vasoconstriction) phenylephrine (Neosynephrine, nasal decongestant) is agonist
Beta-1 in heart, why beta blockers like propranalol were given for high blood pressure
Beta-2 bronchioles, why asthma inhalers had epinephrine

Fig. 9.5 [again]
Many targets are "push-pull" like heart
Some are unique like arterioles (sympathetic only) -- close in peripheral vascular beds (make hands cold), open in muscle (hyperemia).

Anatomy

Fig. 9.3
arrangement of sympathetic output from lateral horn neuron -> white ramus -> sympathetic ganglion -> gray ramus
Simpler for parasympathetic, i.e. from brain stem nucleus or lateral horn in sacral cord to parasympathetic ganglion
called enteric for gut. Contribution of neural network (plexus) to circular and longitudinal muscles to mediate peristalsis. Parasympathetic allows digestion, sympathetic puts it on hold. Atropine blocks muscarinic synapses and is in anti-diarrhea medications to slow motility.

Beautiful women

Clinical Box on page 253 (p 256 in 14th edition)
Atropine muscarinic antagonist
Atropa belladonna (beautiful woman) [deadly nightshade]
SLIDE (Hess, Scientific American, Nov. 1975, p.111) Women are more beautiful with dilated pupils

Channels vs G protein-coupled receptors

Fig. 9.11
use nicotinic and muscarinic to remind you of ionotropic and metabotropic

Heart as an example.

Fig. 14.5
Automaticity at SA and AV nodes (spread from myocardial cell to next myocardial cell). Sympathetic speeds heart, parasympathetic (via vagus, X) slows, and relaxed heart rate is slower than automatic rate.

Male sexual function as an example.

Important aspect of quality of life

Fig. 20.21 (20.22 in 12th edition)
(this is not quite true, see below)

Robert F. Furchgott, Louis J. Ignarro, Ferid Murad Nobel 1998 "for their discoveries concerning nitric oxide as a signalling molecule in the cardiovascular system"

A few years ago, I wrote, "This is the only place where parasympathetic affects arterioles, dilating them in corpus cavernosum for erection. Sympathetic contributes to ejaculation."

Then I read a paper by Ignarro and then his Nobel "speech." Actually, for erection (relaxing arteriole smooth muscle), adrenergic (via alpha 1 receptors) contracts smooth muscle, cholinergic (via muscarinic receptors) inhibits adrenergic-induced-contraction (resulting in relaxation); more than cholinergic and adrenergic, a little mentioned autonomic component, the NANC (nonadrenergic noncholinergic) system, mediates relaxation.

In the 2003 movie Something's gotta give, Jack Nicholson has a heart attack while having sex, and the docs ask if he is on Viagra as they are about to give him nitroglycerine. (also listed in advertisements for ED (erectile dysfunction) medications because of interaction and resulting low blood pressure)

People take nitroglycerine for angina (chest pain), and it releases NO (nitric oxide) and relaxes the coronary arteries

Nitric Oxide (NO), made by endothelial nitric oxide synthase (eNOS), unusual in that it diffuses across "postsynaptic" membrane to affect guanylyl cyclase (GC) involved in making cGMP.
NO was endothelial derived relaxation factor (EDRF), mediator of parasympathetic nervous system's dilation of arterioles in corpus cavernosum. Viagra (sildenafil) inhibits the PDE that breaks down cGMP

Exam questions from 2004 - 2011 relevant to this outline

In the thoraco-lumbar system, in the sympathetic chain of ganglia, postganglionic cells use nicotinic receptors to what neurotransmitter?

acetylcholine

The autonomic nervous system would influence the heart rate (at the SA=sinoatrial node) with 2 types of receptors, beta-1 receptors plus (what other receptor)?

muscarinic

I remind you that the sympathetic nervous system mediates vasoconstriction in peripheral vascular beds. Now your turn. What part of the autonomic nervous system meciates vasodilation (hyperemia) in muscle?

sympathetic

Why doesn't a molecule of cGMP keep mediating smooth muscle relaxation (in arterioles in the corpus cavernosum) forever?

a phosphodiesterase converts cGMP to GMP

Are channels (ionotropic receptors), G protein coupled receptors (metabotropic receptors) or both used in the parasympathetic nervous system?

both, nicotinic at ganglion, muscarinic at effector

31. Which part of the autonomic nervous system utilizes a chain of connected ganglia near the spinal cord?

sympathetic

32. An eye care professional (for ophthalmoscope examination) [or a "beautiful woman", for cosmetic purposes] puts atropine in the eye. Answer either (1) What component of the nervous system is affected? Or (2) What is the pharmacological name of the receptor that is blocked?

parasympathetic

33. Before they knew the chemical identity (NO = nitric oxide) they used an operational name (EDRF = endothelial derived relaxation factor). Answer either (1) What is housed in endothelial cells to make NO? or (2) What is it that was made to relax by this factor?

eNOS (endothelial Nitric Oxide Synthase), smooth muscle in arterioled to the corpus cavernosum

What is the interesting parallel in the actions of Viagra and caffeine?
 
They both inhibit a phosphodiesterase, Viagra inhibits cGMP breakdown and caffeine inhibits cAMP breakdown
 
17. What difference, if any, is there between the neurotransmitter used to activate beta-1 adrenergic receptors vs. beta-2 adrenergic receptors?
 
No difference, norepinephrine for both
 
What chemical does Viagra inhibit?

the phosphodiesterase for cGMP

What gas mediates arteriole dilation by the parasympathetic nervous system?

NO (nitric oxide)

A nasal decongestant spray would contain an agonist for what naturally ocurring neurotransmitter?

norepinephrine

The anatomical term "cranio-sacral" refers to what functional unit?

parasympathetic nervous system

For what condition was propranalol, a "beta blocker," given?

high blood pressure

The anatomical term "thoraco-lumbar" refers to what functional unit?

sympathetic

An asthma spray would contain an agonist for what naturally ocurring neurotransmitter?

norepinephrine

Where are nicotinic receptors used in the autonomic nervous system?

ganglia

In addition to cranial nerves, what other nerves make up the parasympathetic nervous system?

sacral

What is the corpus cavernosum?

erectile tissue

Muscarinic receptors are for what neurotransmitter molecule?

acetylcholine

What would sympathetic activation do to the blood flow in muscle?

increase it

Identify one of the two parts of the central nervous system where the parasympathetic output originates. Be specific.

Brain (for cranial nerves) and sacral part of the spinal cord

Propranalol is a btea-1 blocker, and it is given to patients to prevent the action of what neurotransmitter at what site?

norepinephrine in heart

A patient comes in and his heart is stopping because of exposure to malathion. What do you give him?

atropine

Why would atropine be a useful ingredient in medication for diarrhea with cramping?

inhibits parasympathetic meciated activation of gastrointestinal motility

Why are treatments like nitroglycerine contraindicated for men who are on drugs for erectile dysfunction?

An unsafe drop in blood pressure would result from too much smooth muscle relaxation

"The parasympathetic nervous system dilates arterioles in the corpus cavernosum, mediating erection." Give either of the reasons that this statement is not the whole truth according to more modern research.

(1) actually, the parasympathetic nervous system inhibits the sympathetic for this. Also (2) a non-cholinergic non-adrenergic system is of paramount importance.

"Nicotinic" applies to which place (i.e. preganglionic axon terminal, postganglionic synaptic receptors, postganglionic axon terminal, effector receptors)? Justify.

The acetylcholine receptor on the postganglionic cell body

What specific kind of receptor does atropine block?

Cholinergic muscarinic

Where does nicotine have its effect?

on nicotinic acetylcholine receptors most notably in autonomic ganglia

What is the significance of the endothelial cells that line blood vessels in mediating erection?

endothelial derived relaxation factor (EDRF= nitric oxide[NO]) is made there

In which part of the autonomic nervous system is the ganglion near the neuroeffector junction?

parasympathetic

What specific type of receptor mediates the sympathetic nervous system's effects on the heart?

beta-1

Hyperemia, increased blood flow in skeletal muscle, is mediated by what functional subdivision of the nervous system?

sympathetic

How does a nasal decongestant spray like phenylephrine work?

constricts arterioles

Why would a beta blocker like propranalol be given for high blood pressure?

would block beta adrenergic receptors in heart, decrease heart rate and force or volume

How does Viagra work?

inhibit PDE to break down cGMP

What kind of muscle does the autonomic nervous system connect to?

smooth

Usually your eye care professional will administer something to dilate the pupils. What type of receptor for what neurotransmitter is blocked?

muscarinic for acetylcholine

For which component of the autonomic nervous system is the ganglion closer to the central nervous system?

sympathetic

Explain how vasoconstriction (or the opposite) applies to how a decongestant unclogs a stuffed nose.

An alpha agonist like phenylephrine constricts engorged vascular bed

"Control of arteriole smooth muscle involves "unique" innervation, sympathetic only. Except for (what?).

arterioles to the corpus cavernosum

"This and other erectile dysfunction medications should not be taken if you are taking nitrates for chest pain." Why not?

the combined actions, all causing relaxation of arteriole smooth muscle, would cause an unsafe drop in blood pressure

In one figure, "autonomic ganglia" were shown in a chain near the spinal cord. Which subdivision of the autonomic nervous system is this?

sympathetic

What transmitter receptor would be affected by a spray to unstuff a a stuffed nose, and would you use an agonist or an antagonist?

phenylephrine is an agonist for alpha adrenergic receptors

Why does the inner layer of the blood vessel (the endothelium) come up in an explanation of erection?
 
Endothelial NOS makes NO
 
"The autonomic nervous system is a motor system." Thus the CNS (central nervous system) location of the cell body of origin (not the ganglion) is in the gray matter of the spinal cord and also (finish this sentence).
 
The brain
 
In the somatic motor system, connecting to striated muscle, we refer to the "neuromuscular junction." For the autonomic nervous system, we are more non-committal with the term "neuroeffector junction<"instead. Why?
 
b/c it could also be glands
 
For nicotine, answer either (1) Where (anatomically) does it affect the autonomic nervous system? Or (2) What neurotransmitter is involved?
 
1 the ganglia 2 acetylcholine
 
Via beta-1-adrenergic receptors, the sympathetic nervous system increases the contractility of heart muscle and (in what other way does it affect the heart?).
 
increase rate
 
Why would people have used a muscarinic receptor blocker as a cosmetic?
 
Dilated pupils are appealing


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