Resting Membrane Potential and Local Potential

major cation inside

major cation outside

major anion inside

major anion outside

excess of positive charges outside and negative charges inside the membrane; gives rise to an electrical potential difference which ranges from about 60 - 70 mV

type of channel that opens when the membrane potential changes beyond a treshold value

opens when bound by a specific agonist, initiates depolarization or hyperpolarization of the plasma membrane

RMP of nerve cells

RMP of muscle cells

chemical gradient = electrical potential gradient. potential level across the membrane that exactly opposes net diffusion. allows theoretical membrane potential toe calculated for particular ion

membrane potential results from all the ions that can cross the membrane

stimulate ion channels sensitive to either voltage or pressure but does not produce an action potential

can be summated algebraically

not propagated along the nerve

potentials that decrease in strength as they spread out from the point

are graded, can increase, temporary, not propagated and cannot reach threshold

membrane becomes permeable to sodium ions overshoots beyond zero and becomes somewhat positive

sodium ion channels close; potassium open more

membrane potential becomes more negative than the original resting membrane potential

travel away from the stimulus; all-or-nothing principle

slow channels and responsible for the plataeu portion of action potential

fast channels that is responsible for the spike portion of action potential

excessive flow of potassium; carries tremendous numbers of (+) charges to the outside creating more(-) inside

jump of action potential from node to node; increased velocity of nerve transmission

process of eliciting action potential

stimulus does disturb the membrane potential locally for as long as 1 ms but not sufficient to activate the automatic regenerative processes of the AP

local potential changes

after an action potential; new stimulus can't be elicited because sodium channels are inactivated

period in which 2nd AP cannot be elicited even with a strong stimulus

stronger than normal stimuli can excite the fiber because potassium channels are open; sodium channels still have not been reversed from inactivation state