Action Potentials

cells produce signals called

graded (local) potentials and action potentials

electrical signals

transfer information from one part of the body to another

electrical properties result from

ionic concentration differences across plasma membrane

permeability of membrane

inside of an axon is __ charged

negatively

outside of an axon is __ charged

positively

ion concentration differences depend on a

concentration gradient

many ions have a __ across the membrane

concentration gradient

potassium (K+)

high concentration (intracellular) and low concentration (extracellular)

sodium (Na+)

high concentrations (extracellular) and low concentrations (intracellular)

K+ wants to __ the cell

enter and exit the cell

plasma membrane is much ___ permeable to K+

more

leaky channels are always ___ for K+

open

leaky channels are open for K+ because of he ___ period

refractory

Na+ leaks __ the cell and K+ leaks _ of the cell

into; out

concentrations of ions is maintained by ____ pump

sodium-potassium

sodium-potassium pump actively transports __ sodium ions outside axon and actively transports _ potassium ions inside

3;2

Ion passaged controlled by

ligand gated channels and voltage gated channels

ligand-gated channels

opens when the appropriate chemical binds to receptor

voltage-gated channel

opens and closes in response to changes in membrane potential

sodium concentration is higher ___ the cell

outside

potential difference

unequal distribution exists between the immediate inside and immediate outside of the plasma membrane

depolarization

potential difference becomes smaller

hyperpolarization

potential difference becomes greater

action potential definition

dramatic change in membrane polarity produced by voltage-gated ion channels.