PPT 6- ANS & Sympathetic transmission Flashcards
Exam 2
What is the afferent pathway, and what information is sent?
going towards CNS
a) special sensory receptors - 5 senses, except touch
b) somatic sensory receptors - skin, skeletal muscle, pressure, pain
c) visceral sensory receptors - internal organs
What is the efferent pathway, and what information is sent?
going away from CNS
a) somatic nervous system - conscious control
b) autonomic nervous system - smooth muscle, cardiac muscle, glands. (parasympathetic and sympathetic NS)
c) enteric nervous system
Where are neuron cell bodies for the somatic system located?
in the CNS
has axons that leave the CNS, but cell bodies are in the CNS
Where are neuron cell bodies of the autonomic system located?
outside the CNS (ganglia)
What are the subdivisions of the autonomic nervous system?
sympathetic, parasympathetic, and enteric
What is the enteric system?
primitive system, gut feeling
Where do sympathetic axons leave the CNS?
Thoracolumbar region
For parasympathetic NS, preganglionic fibers are ________, while postganglionic fibers are __________
Preganglionic= long
postganglionic= short
Where do parasympathetic axons leave the CNS?
Craniosacral regions.
Most from brainstem, bladder and genitals from sacral
Sympathetic NS preganglionic fibers release which neurotransmitter?
ACh
Which drugs are direct acting sympathomimetics?
Epinephrine, isoproterenol, albuterol
Which drugs are indirect acting sympathomimetics?
ephedrine and amphetamines
don’t bind directly to receptor, but block the reuptake of NE or reverse the NET, leaving NE in the synapse longer
What effects are seen from sympathomimetics?
Vasoconstriction
Increased inotropic and chronotropic effects
Decrease bronchiole tone
Decreased uterine muscle tone
What are sympatholytics?
drugs that inhibit the sympathetic nervous system
alpha/beta blockers
What effects are seen from sympatholytics?
vasodilation, decreased BP
decreased chronotropy (heart rate)
Which muscarinic receptors are excitatory?
M1, M3, M5
Which muscarinic receptors are inhibitory?
M2, M4
What neurotransmitter(s) acts on cholinergic receptors?
ACh
What neurotransmitter(s) acts on adrenergic receptors?
epinephrine and norepinephrine
How many types of alpha receptors are there?
2
alpha 1
alpha 2
How many types of dopamine receptors are there?
5
D1-5
Which alpha receptors are stimulatory and what does it activate?
alpha 1, activates Gq protein, activates phospholipase C which activates secondary messengers IP3 and DAG
which alpha receptors are inhibitory and what does it inhibit?
alpha 2, inhibits adenylyl cyclase; leads to decreased cAMP
Where is the ganglia located in the sympathetic NS?
Close to the spinal cord
Where is the ganglia located in the parasympathetic NS?
In the visceral effector organs
The enteric NS is mainly under _____ control
parasympathetic
Sympathetic input mainly inhibitory
Many neurons in the enteric NS are mostly _____
non-adrenergic, non-cholinergic (NANC)
What are the effectors of the ANS vs somatic?
ANS - cardiac muscle, smooth muscle, and glands (not skeletal)
Somatic - skeletal muscle
Axons of the ANS are a ___-neuron chain
2
- The preganglionic (first) neuron has a lightly myelinated axon
- The ganglionic (second) neuron extends to an effector organ
In the skeletal muscle, there are ____ ganglion
no
In the ANS, the preganglionic fibers release ____, while postganglionic fibers release ____
ACh
NE or ACh
Parasympathetic NS mostly releases what neurotransmitter?
ACh
The sympathetic NS mostly releases what neurotransmitter?
NE, some ACh (sweat glands)
Sympathetic drugs that mimic the sympathetic nervous system are called _____
Sympathomimetics
Albuterol directly acts on what?
beta receptors in lungs
Sympathomimetics are taken up by ____
NET (NE transporter)
Ionotropic is ____ chronotropic is ____
Force, rate
Phentolamine
Alpha selective sympatholytic
Labetolol
Mixed selective sympatholytic
Are Beta receptors inhibitory or stimulatory?
All beta receptors are stimulatory - stimulates adenylate cyclase, increasing cAMP
What are the types of cholinergic receptors?
Muscarinic and nicotinic
What type of receptors are muscarinic receptors?
GPCRs
What type of receptors are nicotinic receptors?
Ion channels
What are the adrenergic receptors? What do they respond to?
Alpha, beta, dopamine
NE
What are the 2 nicotinic receptor subtypes in the PNS? Where are they located?
Neuronal (occurs at ganglion)
Muscular (occurs skeletal muscle endplates)
Where are dopamine receptors located?
mostly in brain, some in smooth muscle, CV, and kidneys
What is the GPCR that alpha 1 activates? Effector?
Gq/G11 - activates phospholipase C
What is the GPCR that alpha 2 activates? Effector?
Gi - inhibits adenylate cyclase
What is the GPCR that beta activates? Effector?
Gs - stimulates adenylate cyclase
Where are alpha 1 receptors primarily found?
in the smooth muscle cell that surrounds the blood vasculature