Flashcards in ANS Deck (140):
What are the two components of the nervous system?
CNS and PNS
The somatic and autonomic nervous system are a part of which division of the nervous system (CNS or PNS)?
The final common pathway linking the central nervous
system to skeletal muscles is what?
Alpha motor neurons
Efferent axons in the somatic nervous system synapse where?
on effector cells
What are the final common pathways from the CNS to peripheral target organs?
Sympa and parasymp neurons
Does the somatic system have ganglia?
Do the sympatheic and parasymp nerves have ganglia?
How do presynaptic sympathetic neurons compare to postsynaptic side?
Parasympathetic ganglia cells are clustered where?
within walls of visceral organs
How do presynaptic PARAsympathetic neurons compare to postsynaptic side?
Why is the adrenal gland a special case of innervation?
No post synaptic--just hormones released into the blood
What are the two different types of stimuli that the ANS can have?
Excite or inhibit
The somatic α motor neurons are (BLANK) in diameter and therefore allow (BLANK) conduction
The somatic α motor neurons are larger in diameter and therefore allow faster conduction
Where are the cell bodies of the sympathetic division located?
In the intermediolateral columns of the spinal cord, in the thoraco-lumbar section
What are the spinal levels of the sympathetic division?
Axons for the preganglionic symp neurons exit the spinal cord and enter what structure?
White rami communicates
Are most preganglionic symp neurons myelinated or unmyelinated?
What are the three routes that sympathetic nerves take after leaving the spinal cord?
1. To symp chain, where they synapse
2. Through chain, and synapse in specialized ganglia
3. Straight to organ (e.g. adrenal medulla)
What are the two regions of the parasympathetic division?
1. Cranial outflow
2. Sacral outflow
Where parasympathetic nerves from the cranial division synapse?
Near the organ they innervate
Where parasympathetic nerves from the sacral division synapse?
group of scattered pelvic ganglia
True or false: The pelvic ganglia carry both sympathetic and
What are the two division of the enteric nervous system? Where are they located?
Myenteric (between muscular layers of gut tube)
Submucosal layer (beneath circular muscularis mucosae)
What is the function of the myenteric plexus?
controls GI tract motiliy
What is the function of the submucosal plexus?
ion and fluid transport
True or false: The ENS, cannot function without input from the sympathetic or parasympathetic division.
False, it can
What is the ANS?
The portion of the nervous system that controls most VISCERAL functions, and accommodates coordinated responses to external stimuli
True or false: the somatic and ANS are a part of the CNS
False, only the PNS
What are the three divisions of the ANS?
What is the transmitter used in somatic nerves?
What is the neurotransmitter used in the parasymp division of the ANS?
What is the neurotransmitter used in the symp division of the ANS?
What is the significance of the fact that ANS fibers branch out after they synapse?
Can have multiple symptoms in each area
True or false: the eyes and the heart are connected through their parasymp innervation
What is meant by the term dual innervation?
That msot organs receive innervation from both the symp and para, but that they are not antagonistic
What are the exceptions to the dual innervation rule, and receive only sympathetic innervation? (6)
What is the neurotransmitter that all somatic nerves release?
What is the neurotransmitter that all preganglionic nerves release?
Parasympathetic post-ganglionic fibers release what neurotransmitter?
Sympathetic post-ganglionic fibers release what types of neurotransmitters?
What is the neurotransmitter that the sympathetic division of the ANS that innervates sweat glands?
What division of the ANS releases neurotransmitters other that ACh?
Why is the sweat gland's inervation weird?
Its symp innervation, but uses Ach
Symp ASN to cardiac smooth muscle, gland cells, and nerve terminals use what type of neurotransmitter?
Symp ASN to renal vasculature and smooth muscle use what type of neurotransmitter?
All parasympathetic neurons use what type of neurotransmitter?
Somatic nerves use which neurotransmitter?
What are the five steps to cholinergic transmission?
1. synthesis of neurotransmitter
How is acetylcholine synthesized? What is the pump and enzyme used?
1. Choline brought into nerve by choline transporter (CHT)
2. Acetyl-coa + choline = ACh via choline acetyltransferase (ChAT)
What is the group of drugs that can inhibit choline transporters?
How is ACh stored?
1. Vesicle associated transporter (VAT) stores ACh into vesicles
What is the class of drugs that inhibits the vesicle associated transporter (VAT) for ACh?
What are the proteins that concentrate vesicles filled with Ach on the nerve terminal membrane?
VAMPs and SNAPs
What triggers the release of transmitter vesicles? What is the step that happens after that?
Influx of Ca, which binds to calmodulin, and interacts with the VAMP to trigger fusion
The acetylcholine vesicle release process is
blocked by botulinum toxin through what?
the enzymatic removal of two amino acids from one or more of
the fusion proteins
How is ACh's action terminated?
1. Degradation by Acetylcholine esterase
2. Reuptake by autoreceptors
What is the MOA of acetylcholinesterase inhibitors?
What are the two types of cholinergic receptors?
What type of receptor is the muscarinic ACh receptors?
What type of receptor is the nicotinic ACh receptors?
Ion gated channel
What are the breakdow products of acetylcholinesterase?
Acetate and choline
What are the five subtypes of the muscarinic receptors?
What is the source of aqueous humor production in the eye?
Ciliary body epithelium
What is the route of aqueous humor formation?
From ciliary body epithelium, through pupil, to the canal of Schlemm
What is the muscarinic receptor located on the dilator (radial) muscle in the eye?
What is the muscarinic receptor located on the sphincter muscle in the eye? If it is activated, what is the result?
What are the muscarinic receptors located on the ciliary muscle in the eye?
M3 and B2
What are the muscarinic receptors located on the ciliary epithelium in the eye? What is the effect if each one is activated?
Alpha 2, beta 1 and 2
Betas= production of aqueous humor
What is the function of the radial muscle of the eye?
Dilate the eye
If the M3 receptor on the ciliary muscle in the eye is activated, what is the effect on the muscle?
If the beta2 receptor on the ciliary muscle in the eye is activated, what is the effect on the muscle
What are the predominant muscarinic receptors in the heart? What is this responsive to? What are the protein that are downstream of this?
M2, which responds to ACh, and activates a Gi protein, which opens K channels
What is the effect that M2 receptors have on the SA node of the heart?
Decrease heart rate
What is the effect that M2 receptors have on the AV node of the heart?
Decrease conduction velocity
What is the effect that M2 receptors have on the Atrial muscle of the heart?
Decreases atrial contraction
What is the effect that M2 receptors have on the ventricular muscle of the heart?
Decrease ventricular contraction
What are the predominant muscarinic receptors in the bronchi and bronchioles? What is their effect?
What are the predominant muscarinic receptors in the bronchiolar submucosal glands? What is their effect?
To treat asthma patients, would you want to inhibit or activate the muscarinic receptors?
What are the predominant muscarinic receptors in the stomach? What is their effect?
What are the predominant muscarinic receptors in glands? What is their effect?
What are the predominant muscarinic receptors in the intestine? What is their effect?
M3 - diarrhea, involuntary defecation
The bladder wall is richly supplied with parasympathetic cholinergic nerve endings and
has abundant postganglionic cell bodies. What is the muscarinic receptor located here? What does this cause? (3)
1.Contraction of the detrusor muscle
2.Relaxing the trigone
3. Inhibiting contraction of the sphincter
What are the three different vascular smooth muscle cell innervation?
What are the two inputs to vascular cell muscle?
Endothelial cell layer
What are the muscarinic receptors located in vessels? Where are they located?
M3, located on the smooth muscle, and on the endothelial cell surface
When the endothelium of a vessel is intact, activation of M3R on endothelial cells leads to the production of what? What does this cause?
endothelium-derived relaxing factors (EDRFs) = vasodilation
When the endothelium is damaged, activation of M3R on vascular smooth
muscle causes what? How?
vasoconstriction d/t the unopposed EDRFs
What is the MOA behind the muscarinic receptor in smooth muscle of the endothelium in vessels? (3)
Increase [Ca], binds to calmodulin, activates NOS = relaxation
What are the neurotransmitters on the smooth muscle cell side of vessels that activate the alpha 1 and P2x receptors, and cause muscle contraction?
What are the neurotransmitters on the smooth muscle cell side of vessels that activate the P2Y receptors, and cause muscle contraction?
What are the neurotransmitters on the smooth muscle cell side of vessels that activate the CGRP receptors, and counteract muscle contraction?
What are the neurotransmitters on the endothelial cell surface that activate EDRF/NO to produce a relaxing effect?
What happens if there is endothelial cell damage in vessels?
M3 receptor activates smooth muscle contraction
What is the dominant muscarinic receptor in sphincters? What does this cause? What is the one exception to this?
M3, causes relaxation except the lower esophageal sphincter
What is the dominant muscarinic receptor in glands? What does this cause?
Salivation and lacrimation
M1 and M3 protein receptors activate what G protein? What pathway does this activate?
Gq, phospholipase C.. increases PKC
M2 protein receptors activate what G protein? What pathway does this activate?
Gi, inhibits adenylate cyclase... decreases PKA
Where are nicotinic receptors located?
On all autonomic ganglia
What is the nicotinic receptor in the adrenal medulla? What does this cause?
Nn, secretion of epi and norepi
What is the nicotinic receptor in autonomic ganglia? What does this cause?
Nn--stimulation but end effect depends on receptors of organ
What is the nicotinic receptor neuromuscular junctions? What does this cause?
Nm, causes stimulation
Are the Nn and Nm receptor identical?
No, but closely related
What is the precursor for catecholamines?
What is the first step in the synthesis of catecholamines? Enzyme?
Conversion of tyrosine to DOPA by tyrosine hydroxylase
What is the chemical discussed in lecture that inhibits tyrosine hydroxylase (the first step in DOPA synthesis)?
What is the final product in most catecholamine synthesizing neurons?
In dopaminergic neurons, catecholamine synthesis terminates with what?
What is the enzyme that transports dopamine into vesicles?
Vesicular monoamine transporter (VMAT)
What is the drug that inhibits VMAT (the enzyme that transports dopamine into vesicles)?
How does release of dopamine-containing vesicles take place?
Same as in ACh cholinergic endings (VAMPs binding to SNAPs)
What is the only place in the body where norepi is converted into epi?
What is the rate limiting step in dopamine synthesis?
What is the food type that can increase tyramine synthesis, and thus cause an increase in norepi?
What is the MOA for reserpine lowering BP?
Inhibits smooth muscle contraction
What is the chemical that inhibits vesicle release in the catecholamine pathway?
What are the fates of NE when it is in the synapse?
1. Binding to receptor proteins
3. Reuptake by NE transporter (NET)
4. Reuptake by autoreceptors
What is the MOA of cocaine, and tricyclic antidepressants?
Blocks the NET, causing NE is stay in the synapse
What is the MOA of MAOIs?
Inhibits the enzyme monoamine oxidase, which would normally degrade NE
Why can MAOIs increase BP?
Increases NE, which may increase it in vascular signalling
All adrenergic receptors are what?
G protein-coupled receptors.
What are the three major MOA of adrenergic receptors?
Gs (increase adenylate cyclase)
Gi (decrease adenylate cyclase)
Gq (Increase phospholipase C)
What is the G protein in adrenergic β(1 and 2) and α2 receptor activation?
What is the G protein in adrenergic α2 receptor activation?
What are the receptors that activate the Gq protein?
H1, alpha1, V1, M1, M3
What are the receptors that activate the Gs protein?
Beta 1, beta 2, D1, H2, V2
What are the receptors that activate the Gi protein?
M2, Alpha2, D2
What are the receptors that activate the Nn and Nm proteins?
No second messenger--open Na channels
What are the 7 places that alpha 1 receptors are? What is the effect?
Eye (radial dialator muscle)
Bladder (urinary retention)
Kidney (renin release)
For all, think symp
What are the 3 places that alpha 2 receptors are? What are their effects their?
Prejunctional nerve terminal (lower transmitter release)
Pancreas (decrease insulin)
What is the effect of alpha 1 receptor on the external bladder sphincter? Why do you pee your pants when afraid?
Parasymp try to overtake symp
What are the two locations of Beta 1 receptors?
heart and kidney
What are the four areas of the heart that have beta 1 receptors? What does activation of each one do?
SA node (increase HR0
AV node (increase conduction velocity)
Atrial&vent muscle (increase)
His/purkinje (increase conduction velocity)
Where are Beta 2 receptors located?
What is the effect of beta 2 receptors on blood vessels?
What is the effect of beta 2 receptors on blood the uterus?
What is the effect of beta 2 receptors on bronchioles?
What is the effect of beta 2 receptors on skeletal muscle and the liver?
What is the effect of beta 2 receptors on the pancreas?