Electrophysiology Chapter on Membrane Potentials

<p>The cell becomes depolarized. (B)</p> Signup and view all the answers

<p>Alteration in membrane potential (D)</p> Signup and view all the answers

<p>Negative, indicating a lower concentration of positive ions intracellularly. (A)</p> Signup and view all the answers

<p>Graded potentials are typically initiated by synaptic input or sensory stimuli, while action potentials are triggered by reaching a threshold. (B)</p> Signup and view all the answers

<p>Intracellular recording typically measures the membrane potential of a whole cell, while patch clamp allows for the study of current flow through single or multiple ion channels. (C)</p> Signup and view all the answers

<p>Depolarization, indicating an increase in membrane potential. (B)</p> Signup and view all the answers

<p>Inward positive current, moving positive ions into the cell. (C)</p> Signup and view all the answers

<p>Hyperpolarization of the membrane, making the membrane potential more negative. (C)</p> Signup and view all the answers

<p>It is the minimum level of depolarization required to trigger the opening of voltage-gated ion channels and initiate an action potential. (A)</p> Signup and view all the answers

<p>Selective permeability of the cell membrane to different ions and the electrochemical gradients across the membrane. (D)</p> Signup and view all the answers

<p>Potassium ion efflux is low and steady. (D)</p> Signup and view all the answers

<p>The membrane potential considering ionic permeability and equilibrium potentials. (A)</p> Signup and view all the answers

<p>Cryo-electron microscopy (D)</p> Signup and view all the answers

<p>The association of subunits with the cell membrane (D)</p> Signup and view all the answers

<p>To determine which ions pass through the channel (C)</p> Signup and view all the answers

<p>Very low (D)</p> Signup and view all the answers

<p>Its structure was determined using X-ray crystallography. (C)</p> Signup and view all the answers

<p>Equilibrium potential of a specific ion (A)</p> Signup and view all the answers

<p>Trans-membrane input resistance (C)</p> Signup and view all the answers

<p>Measuring ionic currents individually (D)</p> Signup and view all the answers

<p>Potassium (K+) (B)</p> Signup and view all the answers

<p>Increases RM and decreases CM (D)</p> Signup and view all the answers

<p>Na/K pump (C)</p> Signup and view all the answers

<p>It sums all equilibrium potentials weighted by permeability (B)</p> Signup and view all the answers

<p>Larger diameter decreases RI (B)</p> Signup and view all the answers

<p>Potassium efflux (A)</p> Signup and view all the answers

<p>Patch clamp recording of single ion channels (C)</p> Signup and view all the answers

<p>Channel opening, enabling $Na^+$ influx (B)</p> Signup and view all the answers

<p>Sum of ion fluxes through all open channels (A)</p> Signup and view all the answers

<p>Barrier against ion diffusion, maintaining concentration gradients (B)</p> Signup and view all the answers

<p>Establishing and maintaining ion concentration gradients (D)</p> Signup and view all the answers

<p>Preference for permeation of certain ion types over others (D)</p> Signup and view all the answers

<p>Cytoskeletal rearrangement (A)</p> Signup and view all the answers

<p>Intracellular signaling molecules such as G proteins or cyclic nucleotides (B)</p> Signup and view all the answers

<p>They are used to express injected exogenous mRNA coding for channel proteins. (B)</p> Signup and view all the answers

<p>By comparing their responses using patch clamp electrophysiology. (A)</p> Signup and view all the answers

<p>Na channels open with depolarization and inactivate subsequently. (C)</p> Signup and view all the answers

<p>The K channel in oocytes opens with depolarization and closes with hyperpolarization. (C)</p> Signup and view all the answers

<p>Generalized Epilepsy with Febrile Seizures Plus types I and II (B)</p> Signup and view all the answers

<p>It records the electrical activity of ion channels in membranes. (A)</p> Signup and view all the answers

<p>Paramyotonia Congenita (A)</p> Signup and view all the answers

<p>Ion channel conductance can sometimes disobey Ohm’s law. (A)</p> Signup and view all the answers

The difference in electrical potential between the inside and outside of a cell membrane. At rest, the inside of the cell is typically negatively charged compared to the outside.

The movement of ions across the cell membrane, driven by both electrical and chemical gradients.

The ability of a cell membrane to allow certain ions to pass through more easily than others.

The force that drives ions across the membrane, determined by the concentration gradient and the electrical potential difference.

A type of membrane potential change that is localized and decays with distance. It is caused by a transient influx or efflux of ions.

A rapid, transient depolarization of the membrane potential that travels along the axon, allowing communication between neurons.

A technique used to measure the electrical activity of a cell by inserting a microelectrode into the cell's interior.

A technique used to measure the flow of ions across the cell membrane by recording the electrical current through a small patch of membrane.

A type of protein channel that is opened or closed in response to changes in the membrane potential. These channels play a critical role in generating and propagating action potentials.

The movement of ions across a cell membrane through a channel, driven by the concentration gradient and the electrical potential difference.

The selective permeability of an ion channel to specific types of ions. For example, a sodium channel allows sodium ions to pass through but not potassium ions.

This type of channel opens in response to a specific neurotransmitter binding to its receptor. The binding triggers a conformational change in the receptor, which opens the channel allowing ions to flow through the membrane.

This type of channel opens in response to changes in membrane potential. When the voltage across the membrane reaches a certain threshold, it causes a conformational change in the channel, allowing ions to flow through.

The process by which a stimulus triggers the opening or closing of an ion channel.

A type of ion channel gated by the binding of a specific molecule, such as a neurotransmitter or a second messenger.

This type of channel opens in response to mechanical force, such as stretching or pressure. The force causes a conformational change in the channel, allowing ions to flow through.

The electrical potential difference across the cell membrane, which is typically negative inside the cell.

The potential difference across the cell membrane, resulting from the separation of charges. It is typically negative at rest, ranging from -40 mV to -100 mV.

This pump actively transports three sodium ions out of the cell and two potassium ions into the cell, resulting in a net movement of positive charge out of the cell. This contributes to the establishment of the resting membrane potential.

The resting state of a neuron, where the membrane potential is maintained at a constant value.

The Nernst equation calculates the equilibrium potential for a specific ion across a membrane, considering its concentration gradient.

The Goldman-Hodgkin-Katz equation calculates the membrane potential by taking into account the equilibrium potentials of all permeant ions and their respective permeabilities.

The resting membrane potential is the electrical potential difference across the cell membrane when the cell is in a resting state.

The equilibrium potential is the theoretical voltage across a membrane where the electrochemical forces driving an ion across the membrane are perfectly balanced.

The membrane resistance (RM) is the resistance to the flow of charge across the cell membrane. Ion channels act as resistors, controlling the flow of ions.

Axoplasmic resistance (RA) is the resistance to the flow of current within the axon. Myelin, acting as an insulator, decreases RM and increases RA.

Membrane capacitance (CM) is the ability of the cell membrane to store electrical charge. The phospholipid bilayer acts as a capacitor.

The force that drives ions across a membrane, determined by the difference between the membrane potential (VM) and the equilibrium potential (EION) for that ion.

The permeability of the membrane to a specific ion, represented by the conductance (gION) for that ion.

The potential difference across a membrane at which there is no net movement of a specific ion.

A membrane potential that is more negative than the resting membrane potential, closer to the equilibrium potential for potassium (EK+).

A membrane potential that is more positive than the resting membrane potential, closer to the equilibrium potential for sodium (ENa+).

The ability of a membrane to conduct electrical signals passively, determined by the length constant and time constant.

The distance over which a signal can travel passively before decaying to 37% of its original amplitude.

Oocytes are cells that can be used to study ion channels. They do not have their own ion channels, but they can express injected mRNA coding for channel proteins.

Oocytes can express injected exogenous mRNA coding for channel proteins and traffic these into the membrane. This allows for functional study of ion channels.

Patch clamp electrophysiology is a technique that allows researchers to study the function of ion channels in oocytes. They can compare normal channels to those mutated in disease.

Sodium (Na+) channels are responsible for the rapid depolarization phase of action potentials. They open when the membrane potential becomes more positive and then inactivate. They close when the membrane potential returns to a negative value.

Potassium (K+) channels open when the membrane potential becomes more positive and close when the membrane potential becomes more negative. They are responsible for repolarization of the action potential, but not for setting the resting membrane potential.

Channelopathies are diseases caused by mutations in ion channel genes. These mutations can lead to problems with excitability in various tissues, including skeletal muscle and the brain.

Hyperkalemic periodic paralysis is a channelopathy that affects skeletal muscle. It is caused by mutations in the sodium channel gene SCN4A.

Generalized epilepsy with febrile seizures plus is a channelopathy that affects the brain. It is caused by mutations in the sodium channel gene SCN1A.