Nervous System Animations

The sodium-potassium pump (Na⁺-K⁺ ATPase) helps the cell maintain concentration gradients of both sodium (higher outside the cell) and potassium (higher inside the cell).

From http://bio.winona.edu/berg/Free.htm

Gated channels continue to be investigated by researchers.  This image of a gated potassium channel shows four pieces that fit together to barely allow K⁺ through a narrow channel when the gate is open.

Use this link to visit an interactive animation to learn the role of voltage gated channels in producing an action potential. 

(the details of the mechanism may not work exactly this way, but the basic concept is the focus here)

From http://bio.winona.edu/berg/Free.htm