HMB200H1 Lecture Notes - Lecture 4: Opioid, Sodium-Potassium Alloy, Myelin
Document Summary
The conc gradient and the voltage gradient are pulling the na inwards. For k the nernsy equation value is 10/1 = 55mv. For the small leak channel, v = ir. The action: they guessed correctly that this is due to a very small change in sodium permeability causing the spike. If the voltage reaches a certain threshold in the integration zone, they all start opening. If the voltage does(cid:374)"t get high e(cid:374)ough, they do(cid:374)"t ope(cid:374) a(cid:374)d the sig(cid:374)al stops. One of the transmembrane domains has lots of charged amino acids on it and it seems to be respobible for the change in voltage allowing the chanel to open/close. The more they open, the moore often they open or they could open for longer periods of time. Mechnical stress or heat can open in channels at sensory endings like n the skin. Myelin insulates the axon so the action potential can go further and faster.
