Membrane Potentials and Ion Channels in Neurons

These flashcards cover key concepts of membrane potentials, ion channels, and their contributions to neuronal function.

What is the cause of differences in electrical charges across a membrane?

The unequal distribution of ions across the membrane.

What ions primarily contribute to the resting membrane potential?

Potassium (K+) and Sodium (Na+).

What type of ion channels are usually open and key for establishing resting membrane potential?

Leak channels.

What type of channels respond to chemical stimuli?

Ligand-gated channels.

What do mechanically-gated channels respond to?

Mechanical disturbances like pressure, touch, or vibration.

What is the role of voltage-gated channels?

They respond to direct changes in the membrane potential.

Which ions move from areas of higher concentration to areas of lower concentration across a membrane?

Ions usually move down their concentration gradient.

What defines the resting membrane potential of a neuron?

The voltage difference when neurons are not active, typically -70 to -80 mV.

What factors contribute to the resting membrane potential?

Unequal ion distribution, Na+/K+ pumps, and impermeable anions.

What is the Nernst potential?

The diffusion potential that exactly opposes the net diffusion of a particular ion through the membrane.

What does the Goldman equation relate to?

The diffusion potential to the concentration and permeability of several ions across the membrane.

What is the primary function of the Na+/K+ pump in maintaining resting membrane potential?

It pumps three Na+ ions out of the cell and two K+ ions into the cell, actively contributing to the unequal ion distribution and making the inside more negative.

How do impermeable anions contribute to the resting membrane potential?

Large negatively charged molecules (anions) trapped inside the cell contribute to the negative charge within the cell and cannot easily cross the membrane.

What are the typical relative concentrations of Na+ and K+ ions across the cell membrane at rest?

There is a higher concentration of Na+ outside the cell and a higher concentration of K+ inside the cell.

What is a 'concentration gradient' in the context of ion movement?

It is the difference in the concentration of ions between two regions, driving ions to move from an area of higher concentration to an area of lower concentration.

What is an 'electrical gradient' and how does it affect ion movement?

It is the difference in electrical charge across the membrane, which can attract or repel ions, influencing their movement, e.g., positive ions are attracted to negative charges.