The Neuron Action Potential And Synaptic Transmission Flashcards
What ion can block fast Sodium channel?
Calcium
Why chronic hyperkalemia reduce neuronal excitability? (Remember acutely increases it)
- Na channels remain at inactivated state ▶️ Em never return to its original value ▶️ “locked” ▶️ ⬇️ Na channels available to open
Which is the primary mechanism of repolarization?
Open potassium channels
Which drugs can block the fast Na channels, preventing the action potential?
Tetrodotoxin (TTX), Saxitoxin (STX), local anesthetics (“caine drugs”)
What does the Ciguatoxin (CTX: fish) and batrachotoxin (BTX: frogs) do at Na channels?
Block inactivation of fast Na channels
What is the difference between multiple sclerosis and Guillain-Barré syndrome?
- MS: demyelinates at CNS
- GBS: demyelinates at peripheral neurons
What type of channel is the Nicotinic receptor of the muscle membrane (Nm)?
Non-selective monovalent cation channel (both Na, K can traverse)
What substance destroys the proteins needed for the fusion and release of synaptic vesicles in cholinergic neurons? What is the consequence?
- botulinum toxin (protease)
- flaccid paralysis
What does the larotoxin do? Where do you find it?
- opens presynaptic calcium channels ▶️ excess Ach release
- venom of black-widow spider
How do the pesticides affect the cholinergic reactions?
- block acetyl colinesterase ▶️ prolonged action of Ach in cholinergic synapses
What is the difference between non-depolarizing and depolarizing neuromuscular blocker?
- non-depolarizing: block Nm receptor
- depolarizing (succinylcholine): binds to Nm receptor ▶️ channel remain open
What is the difference between myasthenia gravis and lambert-eaton syndrome?
- MG: auto antibodies block Nm receptors
- lambert-eaton: auto antibodies blocks presynaptic voltage-gated Ca channel
Which are the inhibitory postsynaptic receptors and their corresponding ligands?
- GABA (A&C): GABA ligand
- Glycine: Glycine ligand
