Bio Unit 1

Plasma membranes can generate and propagate electrical signals.

Cell body, dendrites, axon, axon terminals.

Where an axon terminal comes close to another cell & membranes are modified. Where info is transferred using chemical signals (neurotransmitters).

• 100 Billion
• 1 --> 1000

• Housekeeping functions:
• Supplying nourishment, maintaining proper ionic environment.

Do NOT generate action potentials

Pumps embedded in membrane that move ions against concentration gradient.

• Sodium potassium pump:
• 3 Na+ out
• 2 K+ in

Pass ions through diffusion.

Each channel is ion-specific.

Some open, some gated.

The point where the diffusion of K+ ions out is balanced by the movement of K+ ions in due to negative electrical potential

*Very close to resting potential

Basic mechanism by which electrical signals are generated and propagated by neurons involving changes in the polarity of the plasma membrane.

Sudden and major, lasting 1-2 ms. and move along at speeds up to 100 m/s.