Exam 2 key terms Flashcards
Chemical Driving Force:
The force exerted on molecules due to a concentration gradient, causing molecules to move from areas of high concentration to low concentration.
Electrical Driving Force:
The force exerted by the electrical charge difference across a membrane, influencing the movement of charged ions toward opposite charges.
Electrochemical Driving Force:
The combined effect of the chemical and electrical driving forces on ion movement across a membrane
Leak Channel:
A type of ion channel that is always open, allowing ions to move freely down their concentration gradient
Ligand-Gated Channel:
A type of ion channel that opens in response to the binding of a specific chemical (ligand) to a receptor site.
Voltage-Gated Channel
A type of ion channel that opens or closes in response to changes in membrane potential (voltage changes).
Regulation of Ion Movement:
The process by which ion channels and pumps control the movement of ions across cell membranes to maintain cellular homeostasis.
Membrane Potential:
The difference in electrical charge between the inside and outside of a cell, measured across the cell membrane.
Resting Membrane Potential:
The membrane potential of a cell when it is not actively sending signals, typically around -70mV for neurons
Na+/K+ Pump
A membrane protein that actively transports sodium (Na+) out of the cell and potassium (K+) into the cell, helping maintain resting membrane potential.
Polarization
The state of a membrane when there is a difference in charge between the inside and outside of the cell
Depolarization
A reduction in the membrane potential, where the inside of the cell becomes less negative relative to the outside, often due to Na+ influx.
Repolarization:
The return of the membrane potential to its resting value after depolarization, often due to the efflux of K+ ions.
Hyperpolarization:
An increase in membrane potential, where the inside of the cell becomes more negative than the resting potential.
Graded Potential:
A small, temporary change in membrane potential that varies in magnitude and dissipates as it travels, typically occurring in dendrites and cell bodies.
Temporal Summation:
The summing of postsynaptic potentials generated at the same synapse in rapid succession.
Spatial Summation:
The summing of postsynaptic potentials generated simultaneously at different synapses on the same neuron.
Action Potential
A rapid, temporary change in a cell’s membrane potential that occurs when a neuron sends an electrical signal along its axon.
Depolarization
Membrane potential becomes less negative as Na+ ions rush into the cell.
Repolarization:
Membrane potential returns toward the resting state as K+ ions exit the cell.
Hyperpolarization:
The membrane potential becomes more negative than the resting potential, often due to excess K+ leaving the cell before channels close.
Membrane is at resting potential, Na+ and K+ channels are closed.
Resting State:
Na+ channels open, allowing Na+ to flow in, causing the inside of the cell to become more positive
Depolarization:
Na+ channels close, and K+ channels begin to open.
Peak of Action Potential:
K+ flows out of the cell, restoring the negative membrane potential.
Repolarization:
K+ channels stay open too long, causing the membrane to become more negative than the resting potential before returning to rest.
Hyperpolarization:
A stimulus that is strong enough to depolarize the membrane beyond the threshold, triggering an action potential.
Suprathreshold:
Gates on ion channels (like Na+ channels) that open in response to depolarization, allowing ions to flow through the membrane.
Activation Gates:
Gates on ion channels (like Na+ channels) that close after depolarization to prevent further ion flow and help end the action potential.
Inactivation Gates:
The period during an action potential when no new action potential can be initiated, no matter the strength of the stimulus, because Na+ channels are inactivated.
Absolute Refractory Period:
The period after the absolute refractory period when a new action potential can be triggered, but only by a stronger-than-usual stimulus, as the membrane is hyperpolarized.
Relative Refractory Period:
A condition where there is an abnormally low concentration of potassium (K+) in the blood, leading to muscle weakness and potentially affecting heart function.
Hypokalemia:
A condition characterized by an abnormally high concentration of potassium (K+) in the blood, which can affect the excitability of neurons and muscles.
Hyperkalemia:
