Physiology 2130 Chapter Notes - Chapter 4: Axon Hillock, Myelin, Human Wave Attack
25 Dec 2016
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Explain the difference between excitable and nonexcitable cells. Excitable cells: can use resting membrane potential to generate action potential. Action potential: electrochemical impulses that dictate how cells communicate in nervous system. Nonexcitable cells: cannot use resting membrane potential to generate action potential. Draw and label the soma, axon, dendrites, axon hillock, myelin sheath, nodes of ranvier, and terminal boutons of a typical neuron. Voltage-gated sodium channel: specific for sodium, no other molecule will pass through. Inactivation gate closes: na+ can no longer enter cell. Absolute refractory period: no depolarization can be triggered whule gate it closed. Channel returns to resting conformation: inactivation gate open, activation gate closed. Voltage-gated potassium channels: contain only one gate that opens when membrane depolarizes. Gate doesn"t open immediately, only when na+ gate inactivates. After pause, k+ gates open when na+ gate inactivates, allowing k+ out of the cell.
