Transport and Excitable Membranes

Flashcards covering key vocabulary and concepts related to transport mechanisms and excitable membranes in cells.

Plasma Membrane

The thin membrane that surrounds the cell, controlling the movement of substances in and out.

Differentially Permeable

A property of cell membranes that allows some substances to pass through while blocking others.

Electrochemical Gradient

A gradient that involves both concentration difference and electric charge difference across a membrane.

Passive Transport

The movement of molecules across the cell membrane without the use of energy (ATP).

Active Transport

The process of moving molecules against their concentration gradient, requiring energy (ATP).

Nernst Equation

An equation used to measure the equilibrium potential of an ion based on its concentration gradient.

Resting Membrane Potential

The electrical potential across the plasma membrane of a cell in a resting state, typically around -40 to -80 mV.

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

An enzyme that pumps Na+ out and K+ into the cell against their concentration gradients, using ATP.

Action Potential

A rapid change in membrane potential that propagates along the axon, leading to signal transmission in neurons.

Voltage-Gated Channels

Ion channels that open or close in response to changes in membrane potential, crucial for action potentials.

Symport

Type of transporter that moves two different molecules in the same direction across a membrane.

Antiport

Type of transporter that moves two different molecules in opposite directions across a membrane.

Amphipathic Molecules

Molecules that have both hydrophilic (water-attracting) and hydrophobic (water-repelling) properties.

Ion Concentration Gradient

The difference in the concentration of ions across a membrane, influencing movement and potential.

Tight Junctions

Specialized connections between two adjacent cell membranes that prevent leakage of materials.