FTM 73-74 Autonomic Nervous System Physiology Flashcards
What do all somatic motor neurons release? How do their pathways differ from the ANS neurons? What do the ANS neurons release?
Somatic motor neurons are 1 long, heavily myelinated axon extending from the CNS to the effector and it always releases ACh. The ANS pathway has a lightly myelinated preganglionic neuron and an unmyelinated postganglionic neuron. The preganglionic neuron always releases ACh and the postganglionic neuron may release epinephrine/norepinephrine or ACh.
How does the sympathetic response affect the adrenal medulla and blood flow to the organs?
What bodily functions does the PSNS usually control? What happens if the PSNS is blocked?
What tissues receive only SNS or PSNS stimulation?
The neurotransmitter that sympathetic fibers release on their target tissues is almost always ________. What is the exception?
What portion of the adrenal gland is innervated by the preganglionic sympathetic fibers? What types of cells are these?
The middle portion of the adrenal gland called the adrenal medulla
chromaffin cells
What are prevertebral ganglia?
sympathetic ganglia which lie between the paravertebral ganglia and the target organ.
The physiological event elicited by a neurotransmitter depends solely on the _____________.
Receptor
What does Hexamethonium do?
It blocks the nicotinic receptors of the ANS
Cholinergic receptors respond to what? What classes are they divided into?
Acetylcholine
Nicotinic and Muscarinic
All nicotinic receptors are _________________________________.
All muscarninic receptors are _______________________________.
ligand-gated cation-selective channels
GPCRs
What is always the effect of ACh binding a nicotinic receptor? Where are these receptors usually found?
What is the effect of ACh binding a muscarinic receptor? Where are these receptors usually found?
What happens to acetylcholine in the synaptic cleft?
Describe the type of voltage response seen with nicotinic, M2, M1, and Substance P receptors.
Describe the structure and function of the basic nicotinic receptor.
Where are the different types of nicotinic receptors found?
CNS and ganglionic receptors are N2/Nn
The NMJ receptors are N1/Nm
Explain why the nicotinic response is sharp and quick.
How can nicotinic receptors desensitize? How often does this happen? Why?
When a nicotinic receptor is opened, what happens?
Na and K are free to move through it and depolarize the membrane. More Na comes in then K goes out
What is the mnemonic to remember what signaling pathways the different muscarinic receptors activate?
QIQIQ
M1 - Gq
M2 - Gi
M3 - Gq
M4 - Gi
M5 - Gq
What is mnemonic to remember what the different adrenergic receptors do?
QISSS
α1 - Gq
α2 - Gi
ß1 - Gs
ß2 - Gs
ß3 - Gs
Describe how vasodilation occurs?
PSNS activates an M3 receptor on an endothelial cell which will, in turn, lead to the production fo nitric oxide that will freely diffuse into a smooth muscle cell, activate guanalyl cyclase, and cause the muscle to relax
Facts to know about adrenergic receptors
What is a presynaptic receptor?
A receptor found in the synaptic cleft but in the membrane of the presynaptic neuron. It usually serves to sense the presence of the neurotransmiiter released by the presynaptic neuron and then signal to that neuron to stop releasing it
Discuss catecholamine synthesis and storage in a neuron.
A Na+/tyrosine symporter brings Tyrosine into the neuron. Tyrosine hydroxylase the converts tyrosine into L-DOPA, this is the rate limiting step. A neurotransmitter vesicle then transports tyrosine, dopamine precursors, and dopamine ß-hydroxylase into itself using the VMAT (vesicular mono amine transporter) which uses an H+ gradient. NE synthesis finished in the vesicle before it is released into the synaptic cleft
Discuss ACh synthesis and storage in a neuron.
Acetyle CoA (from glycolysis) and choline (reuptake via Na+ symporter, rate limiting step) are combined into ACh by choline acetyltransferase. Vesicular storage of ACh by action of a ACh-H+ antiporter in a vesicle membrane. Vesicel fuses with membrane upon Ca++ influx
What type of receptor can act as both a pre and post synaptic receptor?
α2
What are the 4 ways that catecholamines are cleared from the synaptic cleft?
Describe the autonomic control of the bladder
What are some of the major effects triggered by α1 receptors
What are some of the major effects triggered by α2 receptors?
What are some of the major effects triggered by ß1 receptors?
What are some of the major effects triggered by ß2 receptors?
What are the overall effects of catecholamines on metabolism?
Where are ß3 receptors found?
Adipose tissue
For the adrenergic receptors
For the muscarinic receptors
