Lecture 4: Electrophysiology I

Question 1

why is gradient so important

Answer 1

and water, nutrients, etc with the movement of salts

Question 2

define membrane potential

Answer 2

difference in electrical potential between interior and exterior of cell

Question 3

define electrical force

Answer 3

difference between membrane potential and equilibrium potential

Question 4

what is nernst equation used to describe

Answer 4

the equilibrium potential. looking at concentration comparing outside/inside of cell to find voltage.

Question 5

what is GHK equation used to descrie

Answer 5

takes into account permeability and concentration gradient

in equation Vm= 61 log (P) (concentration outside/inside) …except chloride is inside/outside

Question 6

give equilibrium values of K in and outside cell and V eq

Answer 6

inside: 135 mm
outside: 4

overal Veq = -92mv

Question 7

give equilibrium values of Na in and outside cell and V eq

Answer 7

12 mm inside
140 mm outside
+64

Question 8

give equilibrium values of Cl in and outside cell and V eq

Answer 8

4 inside
116 outside

-88mv

Question 9

what is the only POSITIVE ion that contributes to resting potential

Answer 9

potassium

Question 10

what are the qualities of ion channels?

Answer 10

specificity: ion filter and size and charge of aa lining the filter region. and pore diameter.
and they are gated

Question 11

voltage gated channels

Answer 11

• voltage dependent opening due to conformational change
• voltage independent inactivation
• voltage dependent closing due to hyperpoloraization

Question 12

types of intracellular and extracellular logan binding gated channels

Answer 12

intracellular: cAMP, K ATPase and P2x
P2x allows flow of Na, Ca, K

extracellular: GABA- (CL-) and nicotinic acetylcholine receptor which allows flow of Na, Ca, K,

Question 13

3 types of ion channels

Answer 13

stretch/mechanical
voltage gated
ligand