CVS Practice Test

Which three factors primarily determine membrane potentials?

1. Ion concentration, membrane permeability, ion pumps

2. Membrane thickness, ion sizes, membrane proteins

3. Temperature, ion type, cell size

4. Surface area, ion velocity, cell shape

The correct answer is: Ion concentration, membrane permeability, ion pumps

The three factors that primarily determine membrane potentials are ion concentration, membrane permeability, and ion pumps. Ion concentration refers to the distribution of different ions, such as sodium (Na+), potassium (K+), calcium (Ca2+), and chloride (Cl-), across the cell membrane. These ions create an electrochemical gradient, which is essential for establishing the membrane potential. Membrane permeability indicates how easily ions can pass through the cell membrane. This is influenced by the presence of specific ion channels that allow ions to flow in and out of the cell. The permeability to different ions can vary, thereby affecting the overall membrane potential. Ion pumps, such as the sodium-potassium pump, actively transport ions against their concentration gradients. This action helps maintain the unequal distribution of ions across the membrane, contributing to the resting membrane potential. Together, these factors create a dynamic environment where the membrane potential can change in response to various stimuli, facilitating important cellular processes like action potentials in neurons and muscle cells.