Ion Channel Activity Flashcards
What factors the resting membrane potential depend on?
selective permeability of the membrane
large organic anions in the cytoplasm
ion pumps
What is the cell membrane permeable to at rest?
K
What is required for steady state within the cell?
no net movement of ions into or out of the cell
cell must be in osmotic balance
intra and extracellular solutions must be neutral
Why does K not flow down its concentration gradient at all times?
K flowing out of the cell causes a negative membrane potential which pulls positive cations like K back in
What is the equation for working out the equilibrium for electrical and chemical gradient?
E = RT/zF ln Kout/Kin
What is the equlibrium potential for K?
-85 mV
What is the equilibrium potential for Cl?
-85mV
What is the Na equilibrium potential?
34.3mV
What is the absolute refractory period?
the period where Na channels are inactivated and an AP cannot be generated
What is the relative refractory period?
the period where some Na channels can open but requires a strong depolarisation stimulus
What causes Na channel inactivation?
inactivation chin between domains 3 and 4
Where are sodium channels found in the axon?
nodes of ranvier
Where are K channels found in the axon?
between nodes of ranvier
Where are T-type Ca channels found?
axon hillock
Where are N or P/Q Ca channels found?
presynapse
