resting cell membrane

Question 1

why do all cells have potential difference

Answer 1

allows cell signalling by changing the membrane potential e.g nervous system or in cells such as islets of langerhan for the release of insulin

Question 2

how to measure cell potential

Answer 2

put a negative microelectrode into the cell and run a current and will show a negative potential

Question 3

what is the range that cells charges usually are

Answer 3

-20mv to -90mv

Question 4

important cell potentials need to know

Answer 4

skeletal= -90
smooth muscle= -50
neurones= -70
cardiac= -80

Question 5

how is resting potential set up

Answer 5

in most cells k+ channels are open and k+ leaves town a conc gradient but then re-enters down a potential gradient until an equilibrium is set up and this is where the inside of the cell is negative because more anions left behind in cell

Question 6

what is the Nernst equation

Answer 6

Ek=61/z(mVlog10 [k+]0/[k+]1. this is were ek is the membrane potential if membrane selectively permeable to K+ alone. once equilibrium is reached k+ don’t move anymore and Ek doesn’t change

Question 7

what happens if you change the selective permeability of the cell

Answer 7

this is how you increase or decrease the excitability of a cell. muscle cells need a large influx for threshold value to be reached. less for neurones and smooth muscle