Standard 9d Preknowledge
9d) Students know the functions of the nervous system and the role of neurons in transmitting electrochemical impulses.
CALIFORNIA FRAMEWORKS SUMMARY:
Transmission of nerve impulses involves an electrochemical “action potential” generated by gated ion channels in the membrane that make use of the countervailing gradients of sodium and potassium ions across the membrane. Potassium ion concentration is high inside cells and low outside; sodium ion concentration is the opposite. The sodium and potassium ion concentration gradients are restored by an active transport system, a pump that exchanges sodium and potassium ions across the membrane and uses ATP hydrolysis as a source of free energy. The release of neurotransmitter chemicals from the axon terminal at the synapse may initiate
an action potential in an adjacent neuron, propagating the impulse to a new cell.