how nerves work 2

Question 1

resting potential

Answer 1

keeps cells ready to respond

Question 2

action potential

Answer 2

electrical impulse which is generated along axon

Question 3

generated potential

Answer 3

defines threshold at which AP is fired.

Question 4

how is the resting potential maintained?

Answer 4

There is a higher conc. of K+ inside the cell. there is a higher conc. of Na+ outside the cell. there is a higher conc. of cl- outside the cell.

• Maintained by leaky K+ channels which allow K+ to diffuse out of cell.
• Closer to -70mv than -90mv due to other leaky channels( Na+/ Cl-), Na+/K+ pump which pumps 3 Na+ out of cell for every 2 k+ pumped in, large negatively charged molecules which cannot leave the cell

Question 5

how is K+ concentration maintained in the brain.

Answer 5

astrocytes wrap around the capillaries and lock it tight preventing excess k+ from flowing into the Blood brain barrier and therefore depolarising the cell and causing action potentials to be generated.
the heart unfortunately does not have this so cannot control K+ concentration. this can lead to ventricular fibrillation

Question 6

equilibrium potential

Answer 6

the potential at which the concentration gradient and the electrical gradient of K+ is equal and opposite.
it depends on what the size of the original potential was.

Question 7

what is it called when a cell becomes more +ve compared to the RMP?

Answer 7

depolarises

Question 8

what is it called when a cell becomes more -ve compared to the RMP?

Answer 8

hyperpolarises.