Action Potential (nervous system)

There is a potential on either side of the membranes when:

• the number of ions is different across the membrane (concentration gradient)

• The membrane provides a resistance to ion flow

Passive, or leakage, channels -

always open

Chemically gated channels

open with binding of a specific neurotransmitter

Voltage-gated channels

open and close in response to membrane potential

Mechanically gated channels

open and close in response to physical deformation of receptors

Ions flow along their chemical gradient when they move from an area of … to an area of …

High concentration to low concentration

Ions flow along their electrical gradient when they move toward and are of…

opposite charge