Chapter 7

Question Answer
What is action potential? Sending information in the form of electrical signals
Where does AP originate and travel to? Axon hillock
Leak Channels Always open, throughout neuron, resting membrane potential
Ligand-gated channels Open or close in response to ligand binding, dendrites and cell body, synaptic potentials
Voltage gated channels Open or close in response to change in membrane potential, sodium and potassium channels
What is resting membrane potential? Voltage charge difference across the cell membrane when the cell is at rest
Value of RMP -70 mV
Factors of RMP Ion concentration gradient, membrane permeability to these ion channels
Functions of Na+/K+ pump Moves 3 Na+ out of the cell and 2K+ into the cell. Establishes the concentration gradient and maintains them as well
Polarization Membrane potential is a different potential across the membrane
Hyperpolarization RMP is negative value, a change to a more negative value
Repolarization Membrane potential returns to the RMP following a depolarization
Depolarization in AP Rapid, due to a sudden and dramatic increase in permeability of Na+ and Na+ move into cell, -70mV to +30mV
Re polarization Na+ permeability decreases rapidly, reducing the inflow of Na+, K+ permeability increases, K+ move out of cell, +30mV to -70mV
Hyperpolarization Continuing movement of K+ out of cell
Absolute refractory period Spans all of the depolarization phase plus most of the re polarization phase, a second AP cant be generated in response to a second stimulus regardless of strength of that stimulus, sodium gates are inactive
Relative refractory period Spans last part of repolarization phase and hyperpolarization, Second AP can be generated with a stronger stimulus, some sodium gates closed some inactived

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