Chapter 4_Electrical Properties of Neurons Flashcards
Ion channels
Transmembrane proteins that allow ions to pass through the cell membrane without using cellular energy.
Electrochemical gradient
The combined effect of the electrical gradient (difference in charge) and the chemical gradient (difference in ion concentration) across a membrane that drives the movement of ions.
Nernst equation
A mathematical equation used to calculate the equilibrium potential for an ion based on its charge and concentration gradient across the membrane.
Action potential
A rapid, temporary change in a cell’s membrane potential, caused by the movement of ions across the membrane, that propagates along the axon of a neuron.
Depolarization
A decrease in the membrane potential (the interior of the neuron becomes less negative) that occurs when sodium ions (Na+) enter the cell.
Repolarization
The process of returning the membrane potential to the resting state, typically following depolarization, primarily due to the outflow of potassium ions (K+) from the cell.
Hyperpolarization
An increase in the membrane potential (the interior of the neuron becomes more negative) often caused by the outflow of potassium ions (K+) or the inflow of chloride ions (Cl-).
Voltage-gated ion channels
Ion channels that open or close in response to changes in the electrical potential across the cell membrane.
Ligand-gated ion channels
Ion channels that open or close in response to the binding of specific molecules (ligands) such as neurotransmitters.
Leak channels
Ion channels that are always open, allowing ions to move across the membrane according to their concentration gradient.
Threshold potential
The membrane potential at which an action potential is initiated, typically around -55 mV in neurons.
Sodium-potassium pump
A protein in the cell membrane that uses energy (ATP) to transport sodium ions out of the cell and potassium ions into the cell, maintaining the resting membrane potential.
Nodes of Ranvier
Gaps in the myelin sheath along an axon where action potentials are regenerated.
Saltatory conduction
The process by which action potentials jump from one node of Ranvier to the next, speeding up the transmission of electrical signals along myelinated axons.
Absolute refractory period
The period immediately following an action potential during which a neuron is unable to generate another action potential, regardless of the strength of the stimulus.
Relative refractory period
The period following the absolute refractory period during which a higher-than-normal stimulus is required to generate another action potential.
Synapse
The junction between two neurons where neurotransmitters are released to transmit signals from one neuron to another.
Myelin
A fatty substance that wraps around the axons of some neurons, providing electrical insulation and increasing the speed of action potential transmission.
Goldman-Hodgkin-Katz equation
A mathematical equation used to calculate the membrane potential based on the permeability and concentration of multiple ions.
Tetrodotoxin (TTX)
A potent neurotoxin that blocks voltage-gated sodium channels, preventing the generation and propagation of action potentials.
Resting membrane potential
The electrical potential difference across the cell membrane of a neuron at rest, typically around -70 mV.
Voltage-gated sodium channels
Ion channels that open in response to depolarization and allow sodium ions to enter the cell, initiating the action potential.
Voltage-gated potassium channels
Ion channels that open in response to depolarization and allow potassium ions to exit the cell, contributing to repolarization.
Inactivation gate
A part of the voltage-gated sodium channel that closes to stop the flow of sodium ions during the peak of the action potential.
Patch-clamp technique
An experimental method used to study ion channels by isolating a small patch of membrane and measuring the ionic currents that flow through individual channels.
Graded potentials
Changes in membrane potential that vary in size and do not follow the all-or-none principle, unlike action potentials.
Equilibrium potential
The membrane potential at which the net flow of a particular ion across the membrane is zero, calculated using the Nernst equation.
Permeability
The property of a membrane that determines the extent to which a particular ion can cross it.
Temporal summation
The process by which multiple action potentials in a single neuron combine over time to produce a stronger signal.
Spatial summation
The process by which action potentials from multiple neurons combine to produce a stronger signal.
Chloride ions (Cl-)
Negatively charged ions that contribute to the hyperpolarization of the membrane potential.
Calcium ions (Ca2+)
Positively charged ions that play a key role in neurotransmitter release at synapses.
Transmembrane proteins
Proteins that span the entire cell membrane, involved in various functions including ion transport and cell signaling.
Hydration shell
The layer of water molecules that surround an ion in solution, affecting its movement through ion channels.
Electrical gradient
The difference in electrical charge across a membrane, which can drive the movement of ions.
Chemical gradient
The difference in concentration of a substance across a membrane, which can drive the movement of ions.
Dynamic equilibrium
A state where the concentrations of ions or molecules are stable but ions or molecules continue to move in and out at equal rates.
The “back-of-the-envelope” equation
An informal, approximate calculation used to estimate the equilibrium potential of an ion based on its concentration gradient.
Postsynaptic potentials
Changes in the membrane potential of the postsynaptic neuron caused by the binding of neurotransmitters from the presynaptic neuron.
Excitatory post synaptic potentials (EPSPs)
Depolarizations of the postsynaptic membrane potential that bring the neuron closer to firing an action potential.
Inhibitory post synaptic potentials (IPSPs)
Hyperpolarizations of the postsynaptic membrane potential that make it less likely for the neuron to fire an action potential.
Afterhyperpolarization
The period following an action potential during which the membrane potential is more negative than the resting potential, often due to continued efflux of potassium ions.
Conduction velocity
The speed at which an action potential travels along an axon, influenced by factors such as axon diameter and myelination.
Potassium ion (K+)
Positively charged ion that plays a key role in establishing the resting membrane potential and in repolarizing the membrane during an action potential.
