Chapter 3: Neurophysiology Flashcards
The Generation, Transmission, and Integration of Neural Signals
Neurophysiology
The study of electrical and chemical processes in 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.
Cations
A positively charged ion.
Potassium or Sodim ions
Cations
Protei or chloride ions
Anions
Intracellular Fluid
Cytoplasm - The watery solution found within cells.
Extracellular
The fluid in the spaces between cells (interstitial fluid) and in the vascular system.
Cell Membrane
The lipid bilayer that ensheathes a cell.
Resting Membrane Potential
A difference in electrical potential across the membrane of a nerve cell during an inactive period.
Negative Polarity
A negative electrical-potential difference relative to a reference electrode.
Diffusion
The spontaneous, passive spread of molecules of one substance among molecules of another substance until a uniform concentration is achieved.
Concentration Gradient
Variation of the concentration of a substance within a region.
Ion Channels
A pore in the cell membrane that permits the passage of certain ions through the membrane when the channel is open.
Potassium Ions (K+)
A potassium atom that carries a positive charge because it has lost one electron.
Selective Permeability
The property of a membrane that allows some substances to pass through, but not others.
Sodium Ions (Na +)
A sodium atom that carries a positive charge because it has lost one electron.
Equilibrium
The state in which the number of ions crossing a membrane in one direction is matched by the number crossing in the opposite direction.
Sodium-Potassium Pump
The energetically expensive mechanism that pushes sodium ions out of a cell, and potassium ions in.
Electrostatic Pressure
The propensity of charged molecules or ions to move toward areas with the opposite charge.
Equilibrium Potential
The voltage across a permeable membrane that exactly counteracts the movement of ions from the side with a high concentration to the side with a low concentration.
Calcium Ions
A calcium atom that carries a double positive charge because it has lost two electrons.
Action Potentials
The propagated electrical message a neuron sends along its axon to the presynaptic axon terminals.
Hyperpolarization
An increase in membrane potential (the interior of a neuron becomes even more negative).
Depolarization
A reduction in membrane potential (the interior of a neuron becomes less negative).
Local Potentials
An electrical potential that is initiated by stimulation at a specific site, which is a graded response that spreads passively across the cell membrane, decreasing in strength with time and distance,
Threshold
The stimulus intensity that is just adequate to trigger an action potential.
All-or-None Property
The fact that the amplitude of the action potential is independent of the magnitude of the stimulus.
Afterpotentials
The positive or negative change in membrane potential that may follow an action potential.
Voltage Gated Na+ Channel
A Na+ selective channel that opens or closes in response to changes in the voltage of the local membrane potential. It mediates the action potential.
Refractory
Referring to transiently inactivated or exhausted axonal membrane
Absolute Refractory Phase
A brief period of complete insensitivity to stimuli.
Relative Refractory Phase
A period of reduced sensitivity during which only strong stimulation produces an action potential.
Axon Hillock
A cone shaped area from which the axon originates out of the cell body (integration zone).
Conduction Velocity
The speed at which an action potential is propagated along the length of an axon (section of peripheral nerve).
Saltatory Conduction
The form of conduction that is characteristic of myelinated axons, in which the action potential jumps from one node of Ranvier to the next.
Nodes of Ranvier
A gap between successive segments of the myelin sheath where the axon membrane is exposed.
Multiple Sclerosis (MS)
A disorder characterized by widespread degeneration of myelin.