B2.1 Membrane Transport - HL

Electrochemical Gradient

A gradient of electrochemical potential for an ion across a membrane, comprising a concentration and electrical gradient.

Action Potential

A rapid, temporary change in the membrane potential of a neuron or muscle cell.

Depolarization

A decrease in membrane potential difference, making the inside of the cell less negative.

Repolarization

The process of returning the membrane potential to its resting state.

Gated Ion Channels

Transmembrane proteins forming pores in the cell membrane, allowing specific ions to pass through in response to stimuli.

Voltage-Gated Channels

Ion channels opening or closing in response to changes in electrical potential across the cell membrane.

Ligand-Gated Channels

Ion channels opening in response to the binding of a chemical messenger to the channel protein.

Mechanically Gated Channels

Ion channels opening or closing in response to mechanical forces like pressure or vibration.

Resting Membrane Potential

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

Nicotinic Receptor

A ligand-gated ion channel that opens in response to the binding of acetylcholine, allowing sodium ions to enter.

Sodium-Potassium Pump (Na+/K+ ATPase)

A protein actively transporting sodium out and potassium into the cell using ATP energy.

Direct Active Transport

Movement of molecules across a membrane against their concentration gradient using ATP.

Indirect Active Transport

Movement of molecules against their gradient powered by the movement of another substance without direct ATP use in this step

Cotransporter

A protein facilitating the simultaneous transport of two different molecules or ions across a membrane.

Cell-Adhesion Molecules (CAMs)

Glycoproteins mediating adhesion between cells or between a cell and the extracellular matrix.

Cell Junctions

Specialized structures connecting adjacent cells, facilitating communication and transport.

Adhesive Junctions

Cell junctions providing mechanical stability and support by anchoring cells together.

Tight Junctions

Cell junctions forming a seal between adjacent cells, preventing molecule passage.

Gap Junctions

Cell junctions forming channels between adjacent cells, allowing direct transfer of molecules.

Symporter

A cotransporter protein transporting two or more molecules in the same direction across a membrane.

Antiporter

A cotransporter protein transporting molecules in opposite directions across a membrane.

Neuron

A specialized cell transmitting information through electrical and chemical signals.

Membrane Potential

The voltage difference across a cell membrane due to ion distribution inside and outside the cell.

Voltage

A measure of electric potential difference between two points.

Sodium/Glucose Cotransport

A symport mechanism facilitating glucose transport against its concentration gradient.