Pharmacology Flashcards
what innervates skeletal muscle?
motoneurones
motoneuroens are myelinated true/false
truethey have myelinated axons and cell bodies in the spinal cord
when nearing the muscle the motor neurone axon does what?
divides into unmyelinated branches
branhces further divide into fine branches before enidng with what?
terminal bouton
the terminal bouton forms what with the muscle membrane?
a chemical synpase at the neuromuscular junction
action potentials arising in the cell body are conducted via the ____ to the _____ _____
axon
terminal boutons
what is released following conduction of an action potential?
ACh
where specifically on the muscle fibre does the presynaptic terminal (bouton) synapse?
endplate region of the skeletal muscle fibre
what are the four key structural features of the neuromuscular junction?
terminal bouton
synaptic vesicles
synaptic cleft
end plate region of muscle cell mebrane
which cells of the PNS surround the terminal bouton?
Schwann cells
synaptic vesicles contain what?
ACh
what is the name given to the area where synaptic vesicles cluster awaiting release of their ACh?
active zones
nicotonic ACh receptors are located where?
junctional folds that face the active zones
what are the five steps of synaptic transmission at the neuromuscluar junction?
- Synthesis
- Storage
- Release
- Receptor activation
- Transmitter activation
ACh is synthesised in the cytosol from what?
choline and acetyl coenzyme A
what supplies the acetyl CoA used in the synthesis of ACh?
mitochondria
what enzyme synthesises ACh?
choline acetyltransferase (CAT)
what is the function of vesicular ACH transporters?
to concentate ACh in vesicles
arrival of an action potential at eh terminal casues what?
depolarisation and opening of voltage actived Ca2+ channles allowing Ca2+ entry to terminal
what does the presence of Ca2+ cause at the terminal?
vesicles at active zones fuse with the presynaptic membrane and ACh diffuses into the synaptic cleft
ACh in the synaptic cleft activates what?
post synaptic nicotonic ACh receptors in the endplate region
how are nicotonic ACh receptors assembled?
pentamer of glycoprotein subunits surrounding central cation selective pore (formed from five M2 helices)
the influx of Na2+ is greater than the efflux of K+ through the gate in the nicotonic ACh receptor true/false?
true
what is the name of the depolarisation
