Electrophysiology of Ion Channels and Membrane Potentials

The difference in electrical charge between the inside and outside of a cell membrane.

The stable, negative electrical potential maintained by a cell when it is not actively signaling.

The tendency for ions to move across a membrane due to differences in concentration and electrical charge.

The property of a membrane that allows some substances to pass through more easily than others.

A type of potential change that is graded in magnitude, meaning its size is proportional to the strength of the stimulus.

A type of potential change that is a rapid, all-or-none electrical signal that travels down the axon of a neuron.

A technique that measures the membrane potential of a cell by inserting an electrode into the cell's interior.

A technique that measures the ionic currents flowing through individual ion channels in a cell membrane.

A type of ion channel that opens or closes in response to changes in the voltage across the cell membrane.

The process of sodium ions (Na+) flowing into a cell through open voltage-gated sodium channels.

The process of potassium ions (K+) flowing out of a cell through open voltage-gated potassium channels.

A lipid bilayer that acts as a barrier to the diffusion of ions, keeping ions from freely moving across the cell membrane.

Proteins embedded in the cell membrane that actively transport ions across the membrane, maintaining concentration gradients.

Proteins embedded in the cell membrane that allow ions to passively move across the membrane, following their concentration gradient.

A type of ion channel that is gated by the binding of a neurotransmitter, such as acetylcholine.

The Sodium-Potassium Pump is a protein that actively transports sodium ions (Na+) out of the cell and potassium ions (K+) into the cell. This process requires energy and helps maintain the concentration gradients crucial for generating the resting membrane potential.

The movement of ions across the cell membrane is driven by two forces: the concentration gradient (difference in ion concentration across the membrane) and the electrical gradient (difference in electrical charge across the membrane).

Ion channels are protein pores in the cell membrane that selectively allow certain ions to pass through. They play a vital role in the generation and propagation of electrical signals in neurons.

The difference in electrical potential across a cell membrane due to the uneven distribution of ions.

The theoretical electrical potential at which there is no net movement of a specific ion across the cell membrane.

This equation calculates the equilibrium potential for a specific ion based on its concentration gradient.

This equation calculates the membrane potential based on the equilibrium potentials of all permeant ions and their respective permeabilities.

The relative ease with which an ion can cross the cell membrane.

The resistance to current flow across the cell membrane.

It's like a measure of how much charge can be stored on the membrane.

The force that drives the movement of ions across the cell membrane, determined by both the concentration difference and the electrical potential difference.

The relative ease with which ions can cross the cell membrane, influenced by the number and type of ion channels.

The relationship between membrane potential (VM), ionic driving force (VM - EION), and permeability (gION) for a specific ion.

The ability of a neuron to conduct electrical signals along its length, determined by the passive properties of the membrane.

The distance over which the amplitude of the electrotonic signal decreases to 37% of its original value.

The time it takes for the membrane potential to reach 63% of its final value during a depolarization or hyperpolarization.

Oocytes are cells that have not yet expressed their own ion channels but can be used to study ion channels by injecting them with mRNA coding for the desired channel protein. These injected channels become functional and can be studied using patch clamp electrophysiology.

Channelopathies are diseases caused by mutations in ion channels. Expression systems like oocytes allow researchers to study these mutations and understand their effects on channel function.

Sodium channels are a type of ion channel that allows sodium ions to flow into a cell. They are involved in the generation of action potentials and are critical for nerve and muscle function.

Potassium channels are a type of ion channel that allows potassium ions to flow out of a cell. They are involved in restoring the resting membrane potential after an action potential.

Sodium channels can inactivate after opening. This inactivation prevents further sodium entry and contributes to the repolarization phase of the action potential.

Hyperkalemic Periodic Paralysis (HyperPP) is a condition characterized by episodes of muscle weakness and paralysis triggered by high potassium levels. It is caused by a mutation in the skeletal muscle sodium channel that makes it easier to open.

Hypokalemic Periodic Paralysis (HypoPP) is a disorder characterized by muscle weakness and paralysis triggered by low potassium levels. It is caused by a mutation in the skeletal muscle sodium channel that makes it less likely to open.