Unit 2 Flashcards
(124 cards)
Neurophysiology
The study of the life processes of neurons
Ions
An atom or molecule that has acquired an electrical charge by gaining or losing one or more electrons
Anions
A negatively charged ion, such as a protein or a chloride ion
Cations
A positively charged ion, such as a potassium or sodium ion
Resting Potential
The difference in electrical potential across the membrane of a neuron at rest
Ion Channel
A pore in the cell membrane that permits the passage of certain ions through the membrane when the channel is open
Selective Permeability
The property of a membrane that allows some substances to pass through, but not other
Diffusion
Spread of solute molecules from an area of high concentration to an area of low concentration through a solvent until a uniform solute concentration is achieved
Electrostatic Pressure
The propensity of charged molecules or ions to move toward areas with the opposite charge
Sodium-Potassium Pumps
The energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in
Equilibrium Potential
Movement of ions across the cell membrane is balanced
Electrostatic pressure pulling ions in one direction is offset by the diffusion force pushing them in the opposite direction
Hyperpolarization
An increase in membrane potential, becoming more negative
Depolarization
A decrease in membrane potential, becoming more positive
Local Potential
Electrical potential initiated by stimulation at a specific site
Graded response that spreads passively across the cell membrane
Weaker with time and distance
All or none property
amplitude of the action potential is independent of stimulus size
Action Potential
Rapid reversal of the membrane potential that momentarily makes the inside of a neuron positive
Created by the sudden movement of Na+ ions into the axon
After Potential
change in membrane potential that may follow an action potential
Voltage-Gated Na+ Channel
Na+-selective channel that responds to changes in the voltage of the local membrane potential.
Mediates the action potential = Has recharge period
Absolute Refractory Phase
A brief period of complete insensitivity to stimuli
Relative Refractory Phase
Reduced sensitivity, only strong stimulation produces an action potential
Post-syn Potential
Local potential initiated by stimulation at a synapse
Spreads passively across the cell membrane, decreasing in strength with time and distance
Excitatory Postsynaptic Potential (EPSP)
Depolarizing potential in a neuron normally caused by synaptic excitation
Increases the probability that the postsynaptic neuron will fire an action potential
Inhibitory Postsynaptic Potential (IPSP)
Hyperpolarizing potential in a neuron
Decreases the probability that the postsynaptic neuron will fire an action potential
Spatial Summination
The postsynaptic potentials that reach the axon hillock