Lecture 5: Action Potential Flashcards
what is an action potential
a rapid change in voltage across a cell membrane
what causes a resting membrane potential
imbalance of ions - low concentration of potassium outside but high concentration of sodium outside - vice versa
what does sodium-potassium ATPase do
maintains equilibrium - moves 3 sodium ions out of the cell and 2 potassium ions into the cell maintaining unequal ionic concentration
what doe K+ leak channels do
allow K+ ions to move down the concentration gradient - causes inside to become electrically negative relative to extracellular space
what does the Nerst equation find
the reversal potential of a specific ion across the membrane
how does depolarization occur
when positively charged ions such as sodium and potassium enter the cell, decreasing the cells negative charge
what happens when threshold is reached
action potential is triggered and opens voltage gated sodium channels which leads to electrical excitability
what happens during repolarisation
cell returns to it resting state
- K+ channels open - allows K+ ions to flow out of the cell
- Na+/K+ pump moves 3 Na+ ions out and 2 K+ ions in
what is saltatory conduction
the rapid transmission of nerve impulses along a myelinated axon, where the signal jumps from one node of ranvier to the next
what is the node of ranvier
the gaps between myelin
