Physiology Lecture 1

Front 1

what are the permeabilities of the different ions at resting membrane potential

Back 1

Na+ : low permeability at rest
K+: higher permeability at rest
(about 100x that of sodium)
Ca++: low permeability at rest
Cl- : moderate permeability at rest

Front 2

how to intracellular proteins affect the electrochemical gradient

Back 2

proteins inside the cell create a negative charge

Front 3

how does selective permeability keep a membrane potential, what other factors are involved

Back 3

1. By keeping the proteins (with
their negative charges)in the cell.
2. By not allowing certain ions (e.g.
sodium) to enter the cell.
The Na+/K+ ATPase pumps out 3Na+ and pumps in 2 K+ creating an electrochemical gradient

Front 4

why does K+ tend to move out of the cell

Back 4

because the concentration gradient is a bit stronger then the electrogradient

Front 5

what does Na+ move in so quickly when the ion channels are opened

Back 5

push down gradient both electrically and chemically

Front 6

what is the Nernst Equation

Back 6

it tells us the balance point b/t the electrical and chemical gradient

Front 7

how can channels control what passes through them

Back 7

size of pore and the charge of the amino acids that make them

Front 8

what is the three possible conformations for a membrane channel

Back 8

open
inactivated
closed

the channel may not be able open directly from the inactive state

Front 9

what are the types of channels involved in membrane potential

Back 9

voltage gated: K+, Na+, Ca+
Cl-open at rest, closes with depolarization
K+ leak channels- active at rest