The Nerve Impulse How are electricity and nerves

The Nerve Impulse

How are electricity and nerves different?

Electrochemical Impulse, Pages 418 -425 - Current travels along a wire much faster than the nerve impulse travels along a nerve. - Electrical wires rely on external energy to push electrons along. Nerve Impulses rely on cellular energy (from what source? ) to generate current. -1900, Julius Bernstein, “Nerve impulses are electrochemical messages created by the movement of ions through the nerve cell membrane. ” - 1939, more evidence for theory, action potential observed in a giant axon of a squid.

How do nerve cells become charged? - neurons have a rich supply of + and - ions - the electrochemical event is caused by an unequal concentration of positive ions across the nerve cell membrane.

-in the resting membrane excess + ions accumulate along the outside of the membrane, while excess - ions accumulate along the inside of the membrane, The membrane is polarized. - this separation of charges gives the nerve cell membrane the potential to do work. -upon excitation, the nerve cell membrane becomes more permeable to sodium than potassium. Sodium gates open! - potassium gates close, sodium diffuses into the nerve cell. The rapid inflow of Na ions causes more + ions than - ions on the inside of the cell. The cell is now depolarized. - K ions move out of the cell and restore polarity. The Na-K pump moves the K ions back inside and Na ions outside and the membrane is repolarized.

• Lets have a look at the nerve impulse. Nerve Impulse

The Action Potential

The Synapse