Question

1. Describe what’s happening in each phase- (is the cell negative or positive, where are the ions moving)
   1. Resting membrane potential
   2. Depolarization
   3. Repolarization
2. 4. Hyperpolarization
   5. Relative refractory period
   6. ​​​​​​​Absolute refractory period

Answer 1

Resting membrane Potential - RMP). At rest, inside of the Membrane is Negative and outside is positive. Since kt permeability is greater than Mat perorreability, therefore kt channete maintain the RMP. Depolarisation ( during activation of membrane). At the point of stimulation, a clight decrease in the RMP due to passive redistribution of ions leads to increased kt and at influe, restoring the rmp. When depolarisation exceede Nat channel activation accuse through vollage galed wat channels and when troing level is reached, influex of Nat along its concentration gradient is so great, that it overcome the repdarizing forces and run away depolarisation results. Repolarisation - Repolarisation starts with It effluz due to opening of voltage gated kt channels and decreases in turther nat influx. The opening of voltage gated kt channel is slower and more prolonged than the opening of Nat channels. Kt efflux causes net transfer of positive charge out of the cell that serve to complete repthorisation After depolarisation slowed down and thus a few milliseconds are delayed in restoring the membrane potential At the termination of spike potential kt conduction is

perpolaris ahon It is achieved by slow retuon of kt chornets to the closed state (although the membrane permeability to not has returned to baseline levels) Absolute Refractory Period Begins from the time of firing level is reached until the repolarisation is approxy complete. During this period no stimulus no matter how stoung, can initiate the fresh impulse le second attion potential in this region, nor can an impulse generaled elsewhere pass through this area. Relative Refractory Period- Begins at the end of ARP to the start of the after depolarisation. During this period stimulus shonger than noomal stimolue can cause excitation -