Part 1. You are reincarnated as a beautiful reef fish. You\'re swimming along on
ID: 149274 • Letter: P
Question
Part 1. You are reincarnated as a beautiful reef fish. You're swimming along one day and you notice this large, colorful, slow moving, innocuous snail on the sand below you Before you know it, BLAM!!! The snail sticks you with big, frickin' harpoon (actually a modified radula with a tooth-like spike and a venom gland)! You suddenly realize, "I can't move and that snail is dragging me down towards its version of a mouth. SHIT, that thing's going to eat me." Having retai your physiology knowledge from your past life you accept your doom, by figuring out how it's actually happening. You remember that the cone snails express a number of neuromuscular toxins called conotoxins including the following 1. a-conotoxin: blocks nicotinic acetylcholine receptors 2. ß-conotoxin: blocks acetyl cholinesterase 3. a-conotoxin: prevents fast inactivation of voltage gated sodium channels in neurons. -conotoxin: opens voltage-gated potassium channels on nerve terminals and muscle cells onotoxin; blocks voltage-gated sodium channels in muscle 5. H-c 6. 8-conotoxin: blocks ryanodine Ca2+ channels 7. o-conotoxin: blocks voltage-gated calcium channels xplain how à-conotoxin would affect amplitude of a typical action Question 1: Briefly e potential and signal flow along the axon (the why is important here, you C in a calculation for full credit, 6 points)? ion 2. Outline the basic steps in neuromuscular communication (ie. the synapse) and explain the impact of a-·B- and co-conotoxins on your paralysis (6 points)Explanation / Answer
Answer (1)delta conotoxin is a peptidyl toxin.It prevent fast inactivation of sodium ion channel because it get bound to sodium ion channel . Thus sodium channel remains active and influx of sodium ion will occur and neuron remains depolarised . Means neurons remained in excited state. This delta conotoxin has no action on muscle sodium channel.
Answer-(2) These all neurotoxin make muscle paralysed.
Steps in normal muscle contraction is that initially acetyl choline neurotransmitter acts on post synaptic membrene which is inhibited by alpha conotoxin by binding to acetyl choline binding site .There after acetylcholine estrase enzyme degrade acetylcholine and causes uptake of acteylcholine , this step is inhibited by beta conotoxin.calcium ion channel entry is also essential for depolarisation in muscle but this step is inhibited by omega conotoxin . For muscle relaxation generally opening of potassium channel occur after closing of sodium channel but kappa conotoxin causes potassium channel to remained open .hence muscle remained relaxed / paralysed.