Chapter 4_Electrical Properties of Neurons

Question 1

Ion channels

Answer 1

Transmembrane proteins that allow ions to pass through the cell membrane without using cellular energy.

Question 2

Electrochemical gradient

Answer 2

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.

Question 3

Nernst equation

Answer 3

A mathematical equation used to calculate the equilibrium potential for an ion based on its charge and concentration gradient across the membrane.

Question 4

Action potential

Answer 4

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.

Question 5

Depolarization

Answer 5

A decrease in the membrane potential (the interior of the neuron becomes less negative) that occurs when sodium ions (Na+) enter the cell.

Question 6

Repolarization

Answer 6

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.

Question 7

Hyperpolarization

Answer 7

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-).

Question 8

Voltage-gated ion channels

Answer 8

Ion channels that open or close in response to changes in the electrical potential across the cell membrane.

Question 9

Ligand-gated ion channels

Answer 9

Ion channels that open or close in response to the binding of specific molecules (ligands) such as neurotransmitters.

Question 10

Leak channels

Answer 10

Ion channels that are always open, allowing ions to move across the membrane according to their concentration gradient.

Question 11

Threshold potential

Answer 11

The membrane potential at which an action potential is initiated, typically around -55 mV in neurons.

Question 12

Sodium-potassium pump

Answer 12

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.

Question 13

Nodes of Ranvier

Answer 13

Gaps in the myelin sheath along an axon where action potentials are regenerated.

Question 14

Saltatory conduction

Answer 14

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.

Question 15

Absolute refractory period

Answer 15

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.

Question 16

Relative refractory period

Answer 16

The period following the absolute refractory period during which a higher-than-normal stimulus is required to generate another action potential.

Question 17

Synapse

Answer 17

The junction between two neurons where neurotransmitters are released to transmit signals from one neuron to another.

Question 18

Myelin

Answer 18

A fatty substance that wraps around the axons of some neurons, providing electrical insulation and increasing the speed of action potential transmission.

Question 19

Goldman-Hodgkin-Katz equation

Answer 19

A mathematical equation used to calculate the membrane potential based on the permeability and concentration of multiple ions.

Question 20

Tetrodotoxin (TTX)

Answer 20

A potent neurotoxin that blocks voltage-gated sodium channels, preventing the generation and propagation of action potentials.

Question 21

Resting membrane potential

Answer 21

The electrical potential difference across the cell membrane of a neuron at rest, typically around -70 mV.

Question 22

Voltage-gated sodium channels

Answer 22

Ion channels that open in response to depolarization and allow sodium ions to enter the cell, initiating the action potential.

Question 23

Voltage-gated potassium channels

Answer 23

Ion channels that open in response to depolarization and allow potassium ions to exit the cell, contributing to repolarization.

Question 24

Inactivation gate

Answer 24

A part of the voltage-gated sodium channel that closes to stop the flow of sodium ions during the peak of the action potential.

Question 25

Patch-clamp technique

Answer 25

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.

Question 26

Graded potentials

Answer 26

Changes in membrane potential that vary in size and do not follow the all-or-none principle, unlike action potentials.

Question 27

Equilibrium potential

Answer 27

The membrane potential at which the net flow of a particular ion across the membrane is zero, calculated using the Nernst equation.

Question 28

Permeability

Answer 28

The property of a membrane that determines the extent to which a particular ion can cross it.

Question 29

Temporal summation

Answer 29

The process by which multiple action potentials in a single neuron combine over time to produce a stronger signal.

Question 30

Spatial summation

Answer 30

The process by which action potentials from multiple neurons combine to produce a stronger signal.

Question 31

Chloride ions (Cl-)

Answer 31

Negatively charged ions that contribute to the hyperpolarization of the membrane potential.

Question 32

Calcium ions (Ca2+)

Answer 32

Positively charged ions that play a key role in neurotransmitter release at synapses.

Question 33

Transmembrane proteins

Answer 33

Proteins that span the entire cell membrane, involved in various functions including ion transport and cell signaling.

Question 34

Hydration shell

Answer 34

The layer of water molecules that surround an ion in solution, affecting its movement through ion channels.

Question 35

Electrical gradient

Answer 35

The difference in electrical charge across a membrane, which can drive the movement of ions.

Question 36

Chemical gradient

Answer 36

The difference in concentration of a substance across a membrane, which can drive the movement of ions.

Question 37

Dynamic equilibrium

Answer 37

A state where the concentrations of ions or molecules are stable but ions or molecules continue to move in and out at equal rates.

Question 38

The “back-of-the-envelope” equation

Answer 38

An informal, approximate calculation used to estimate the equilibrium potential of an ion based on its concentration gradient.

Question 39

Postsynaptic potentials

Answer 39

Changes in the membrane potential of the postsynaptic neuron caused by the binding of neurotransmitters from the presynaptic neuron.

Question 40

Excitatory post synaptic potentials (EPSPs)

Answer 40

Depolarizations of the postsynaptic membrane potential that bring the neuron closer to firing an action potential.

Question 41

Inhibitory post synaptic potentials (IPSPs)

Answer 41

Hyperpolarizations of the postsynaptic membrane potential that make it less likely for the neuron to fire an action potential.

Question 42

Afterhyperpolarization

Answer 42

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.

Question 43

Conduction velocity

Answer 43

The speed at which an action potential travels along an axon, influenced by factors such as axon diameter and myelination.

Question 44

Potassium ion (K+)

Answer 44

Positively charged ion that plays a key role in establishing the resting membrane potential and in repolarizing the membrane during an action potential.