PHAR 340 Lecture Notes - Lecture 14: Adenylyl Cyclase, Muscarinic Acetylcholine Receptor M2, Muscarinic Acetylcholine Receptor
14 Oct 2019
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Lecture 14
What is the control for
arterial pressure?
Baroreceptor reflex
What is the baroreceptor
reflex limited by?
Activation of stretch receptors in the walls of large arteries in chest/neck
Where are baroreceptors
found?
Walls of internal carotid artery above bifurcation
Wall of aortic arch
Response to increase in bp
Glossopharyngeal nerve via carotid baroreceptors
Integration in medulla oblongata, increase nerve firing
Vagus nerve to terminal ganglion in heart
Hr decreases, bp decreases
What do para/sym do?
Don’t reverse change back to normal
Buffers rate of change to prevent large changes in bp
Blunts further increase/decrease
Response to decrease in bp
Glossopharyngeal nerve via carotid baroreceptors
Integration in medulla oblongata
Spinal cord to sym nerve
Hr increases, bp increases
Autonomic
neurotransmission
Nerve impulse -> depol -> Ca2+ entry -> synaptic vesicle exocytosis -> diffusion
of NT across neuroeffector junction -> activate NT receptors -> depol
postgang neuron or effector cell
How can action be
terminated?
Slow: diffuse away (drive via CG enhanced by reuptake at another location)
Fast: enzymatic breakdown so no longer active (Ach)
Cholinergic
neurotransmission
Ach stored in vesicles for exocytosis
Vesicle goes to membrane, fuses, releases contents
What modulates release of
vesicle?
Hemicholiniums: block choline transport
Vesamicol: can’t make vesicle, uncontrolled release of NT
Botulism toxin: can’t exocytose, bind to SNAPs
Black widow venom: allow lots of Ca2+ in so NT rushes out
What is needed to make
Ach?
Acetate from mitochondria choline from transporter
Diet, blood, breakdown
Termination of effect
Ach esterases – fast
Receptor antagonists
How long does a molecule
stay on the receptor?
Short time
Can re-use
Cholinergic receptors
Nicotinic
Muscarinic
Nicotinic receptors
NM (neuromuscular): skeletal muscles – voluntary muscle
NN (ganglionic): pregang to postgang, adrenal medulla – autonomic ganglia
Undergo rapid desensitization
NN and NM are structurally different
Ligand gated ion channels (Na+ and some Ca2+)
Non-specific nicotine and Ach
