Understanding Membrane Potential and Ion Gradients

These flashcards cover key vocabulary related to membrane potentials and ion gradients based on a detailed lecture.

Concentration Gradient

A difference in the concentration of a substance across a space.

Electrical Gradient

A difference in the electrical charge between two regions.

Membrane Potential

The electrical potential difference across a cell membrane, usually measured in millivolts.

Equilibrium Potential

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

Nernst Equation

An equation used to calculate the equilibrium potential for a specific ion based on its concentration gradient.

Sodium-Potassium Pump

A membrane protein that helps maintain the concentration gradients of sodium and potassium across the cell membrane.

Electrochemical Equilibrium

A state where the electric and chemical gradients for an ion are balanced, resulting in no net movement of that ion.

Facilitated Diffusion

The process of passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins.

Ion Channel

A protein structure that allows ions to pass through the membrane in response to a signal or concentration gradient.

Phospholipid Bilayer

A double layer of phospholipids that makes up the cell membrane, isolating different charge regions.

Concentration Gradient

A difference in the concentration of a substance across a space.

Electrical Gradient

A difference in the electrical charge between two regions.

Membrane Potential

The electrical potential difference across a cell membrane, usually measured in millivolts.

Equilibrium Potential

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

Nernst Equation

An equation used to calculate the equilibrium potential for a specific ion based on its concentration gradient: E{ion} = \frac{61.5}{z} \log \frac{[ion]{out}}{[ion]_{in}}.

Sodium-Potassium Pump

A membrane protein that helps maintain the concentration gradients by moving 3 \text{ Na}^{+} out and 2 \text{ K}^{+} into the cell using ATP.

Electrochemical Equilibrium

A state where the electric and chemical gradients for an ion are balanced, resulting in no net movement of that ion.

Facilitated Diffusion

The process of passive transport of molecules or ions across a biological membrane via specific transmembrane integral proteins.

Ion Channel

A protein structure that allows ions to pass through the membrane in response to a signal or concentration gradient.

Phospholipid Bilayer

A double layer of phospholipids that makes up the cell membrane, isolating different charge regions.

Resting Membrane Potential

The steady-state electrical potential of a cell membrane when it is not being excited, typically around -70 \text{ mV} in neurons.

Goldman-Hodgkin-Katz (GHK) Equation

An equation used to calculate the membrane potential by accounting for the concentration gradients and relative permeabilities of all ion species present.

Depolarization

A change in the membrane potential that makes it less negative (closer to zero or positive) compared to the resting potential.

Hyperpolarization

A change in the membrane potential that makes it more negative than the resting potential.

Graded Potential

A local change in membrane potential that varies in magnitude depending on the strength of the stimulus.

Primary Active Transport

Transport of molecules across a membrane against their gradient using energy directly from the hydrolysis of ATP.

Secondary Active Transport

Transport of a substance against its gradient coupled to the downhill movement of another substance, utilizing the energy stored in electrochemical gradients.