A&P - Action Potential

exam 2

multiple sclerosis (MS)

autoimune disease

loss of vision and general motor control

guillain-barre syndrome

triggered by virus

weakness/tingling in arms and legs

diphtheria

results from bacterial infection

sensroy and motor problems that can lead to paralysis

sodium and potassium leak channels

K+ leak permeability out of the cell

Na+ leak permeability into the cell

balance of two determiens resting membrane potential

resting membrane potential

the charge difference across the cell membrane when the cell is at rest

3 types of ion channels

chemically gated, voltage-gated, mechanically gated

action potential (nerve impulses)

self-regenerating wave of electrochemical activity that allows neurons to carry a signal over a distance

all or none!

depolarization to threshold

voltage-gated sodium channels open at threshold 

actrivation of channels and rapid depolarization

sodium ions rush into the cell (rapid depolarization) 

-60 mV to a positive value 

inactivation of channels and activation of potassium channels

voltage-gated sodium channels close

potassium ions move out of cell (repolarization) 

closing of potassium channels

potassium channels close as the membrane repolarizes to the threshold

leak channels 

are always open

voltage-gated channels

are open where there is a change in charge

resting value

-70 mV

absolute refractory period

the membrane cannot respond to further stimulation 

cannot make action potential 

relative refactory period

the membrane can respond only to a larger-than-normal stimulus

propagation

action potential (signals) move forward

saltatory conduction

jumping from node to node 

hypopolarization

too negative

too much sodium can lead to what?

restlessness, tremors, fluid imbalances