Membrane Potential & Ion Review

Two main types of ion channels

leakage and gated channels

Leakage channels

always open

Two main types of ion channels

leakage and gated channels

Leakage channels

always open

Gated channels

part of the protein changes shape to open/close the channel

Three main gated channels

Ligand (Chemically) gated, Voltage-gated, and Mechanically gated

Ligand (Chemically) gated

opens when a neurotransmitter binds

Voltage-gated

Opens and closes in response to membrane potential change

Mechanically gated

Opens and closes in response to physical deformation

electrochemical gradient

electrical and chemical gradients combined

Voltage

a measure of potential energy generated by separated charges

Current

flow of electrical charge (ions) between two points

Resistance

hindrance to charge flow

Insulator

substance with high electrical resistance

Conductor

substance with low electrical resistance

Ohm's law

gives relationship of voltage, current, resistance

resting membrane potential (RMP)

-70 mV

Polarized

Cytoplasmic side of membrane (inside) is negatively charged relative to the outside

Extracellular fluid (ECF) concentration

higher concentration of Na+

Intracellular fluid (ICF) concentration

higher concentration of K+

Cell membrane is more permeable to

K+ than Na+

Sodium-potassium pump stabilizes

resting membrane potential

Na+K+ pump rule of thumbs

3 Na+ out, 2 K+ in

Depolarization

decrease in membrane potential

Repolarization

bring membrane potential back to RMP

Hyperpolarization

increase in MP (inside becomes more negative)

When does inside become less negative?

during depolarization

When does the inside become more negative?

during hyperpolarization