10/13 Anatomy & Physiology of Neuromuscular Junction - Roger & Izard 2017 (Completed) Flashcards
What is the muscle to neuron relationship? 2
muscles fibers are innervated by a single motor neuron (motor unit)
What occurs during the junctional transmission step of neurotransmission? 3
Synthese of Ach
Storage of Ach
release of Ach
destruction of Ach
How is Acetylcholine (ACh) synthesized in the neuron? 5
choline transported into cell via CHT receptor
Acetyl-CoA from mitochondria combines w/ choline via Choline Acetyltransferase (ChAT)
How is Acetylcholine (ACh) loaded into vesicles? 6
via the transporter protein ACh vesicular transporter (VAT)
utilizes ATP
what magnitude of ACh vesicles are present at the pre-synaptic cleft? 7
100,000s
How is ACh released from their vesicles into the synaptic cleft? 7
depolarization of the neuron causes voltage-gated Ca2+ channels to open (VGCC)
Ca2+ induces vesicles to release contents into synaptic cleft
What are the docking and fusion of vesicle to PM proteins? 8
VAMP
SNAPs (SNAP 25)
What is vesicle release dependent on? 8
Signal strength
Cell type
What breaks down acetylcholine after transmission? What is ACh broken down into? 10
Acetylcholinesterase (AChE)
Broken down into:
Choline
acetate
What utilizes Nicotinic (inotropic) receptors? 12
Skeletal muscle
What utilizes Muscarinic (metabotropic) receptors? 12
Smooth muscle
Cardiac muscle:
decrease HR
decreased conduction velocity
What are the five subtypes of Muscarinic ACh receptors in mammals? 13
M1, M4, M5 –> CNS
M2 –> Heart
M3 –> Smooth muscle
how many subunits are there in a Nicotinic ACh receptor? 14
4 subunits
Receptor requires 2 ACh for activation
What amino acids line a nicotinic ACh receptor? 15
Negatively charged aa’s
Aspartic acid
glutamic acid
What is a Nicotinic ACh receptor selective to? 15
Na+
Ca2+
K+
What are the subtypes of Nicotinic ACh Receptors? 17
Nm –> α, β, γ, δ, ε
Nn –> α, β or α only
What is the role of laminin-β2?
Tethers the vesicle to the nerve cell
What is Tetrodotoxin? 11 Izard
Drug contained within flesh of puffer fish
Blocks CNS/PNS
What is the mechanism of action of Tetrodotoxin? 11 Izard
Blocks diffusion of Na+ through Na+ channel
Prevents depolarization = no action potential
What drugs does Bupivacaine interact with? 14 Izard
Prolongs hypertension in pts with MAOIs and TCAs
What is the action of Botulinum toxin? 15 Izard
Prevents release of ACh from axon endings @ NMJ
Causes paralysis
What is the action of Tetanus Toxin? 18 Izard
Causes extreme lockjaw
Travels to spinal cord and causes muscle cramps
