Cellular response to AP Flashcards
What is the relationship between action potentials and amount of neurotransmitter released at nerve terminals?
More APs = more Ca2+ into presyn terminal = more transmitter
Are Na and Ca channel’s alpha subunit similar in structure?
Yes
Are Ca2+ channels diverse or not (many types?)
Yes - many
What does Nifedipine do?
Ca2+ channel blocker
What do both Na and Ca channels need, and what two things may they have to help with fine tuned regulation?
Pore forming region
Glycosylation sites/Phosphorylation sites
How do Ca2+ channels inactivate/activate (compare to Na+)
Activate and Inactivate slowly compared to fast Na channels
Inactivation is Ca2+ dependent
How is transmitter released? Talk through the stages (5)
1) Ca entry through VOCCs
2) Ca binds to synaptotagmin
3) Vesicle brought close to membrane
4) Snare complex makes a fusion pore
5) NT released
How many ACh bind to nAChR and what do they allow through ion channel?
2 x bind
cations - Na in K out
Towards ENa, away from EK when action potential occuring
How does a muscle AP occur if ACh acts so quickly and so locally?
The depol caused by AP locally activated adjacent VGNa+ channels = Na in = depol
Name a competitive nAchR blocker and depolarising blocker
Tubocurarine
Succinyl Choline
How does succinylcholine work?
Ach Depolarises membrane, succinyl binds, maintains depol = Na channels inactivate and cannot be depolarised adjacently
What happens in Myasthenia gravis? Do symptoms improve or worsen with exercise?
Antibodies against nAChRs on post syn membrane of skeletal muscle = less receptors = reduced EPP
Worsen with exercise
What is the difference between an EPP and EPSP?
EPP - is NMJ
EPSP is nerve cells
