25 Questions
What is the typical range of membrane potential found in most cells?
-30 to -90 mV
Which ion is closest to its equilibrium in an unstimulated neuron?
Potassium
What is the primary function of leak channels in a cell membrane?What is the primary function of leak channels in a cell membrane?
To facilitate the diffusion of ions across the membrane
Which statement accurately describes the role of the sodium-potassium pump (Na-K pump)?
It maintains ion concentration gradients by pumping sodium out and potassium in.
What is the major factor contributing to a cell's membrane potential?
The diffusion potential created by ion movement
The sodium equilibrium potential in a cell with a membrane potential of -85 mV is approximately:
+60 mV
What is the physiological justification for the existence of leak channels in cell membranes?
To enable rapid changes in membrane potential
According to the cable model, the membrane potential of a cell is equal to the Nernst potential for an ion when:
The ion's net flow through the membrane is zero
Electroneutrality of a cell means:
The cell has equal amounts of positive and negative charges
The Goldman-Katz equation is used to predict membrane potential by considering:
Potassium, sodium, and chloride ions
How does electroneutrality condition affect the ion current through a cell membrane?
It ensures the total ion current through the membrane is zero.
The diffusion potential in a cell membrane is primarily created by:
Movement of ions across the membrane
The diffusion potential, which is a large component of the membrane potential, is primarily created by the movement of ions across the cell membrane.
Ion conductance and equilibrium potentials
Which statement is true about the Goldman-Katz equation?
It is used to predict membrane potential considering potassium, sodium, and chloride ions.
How does the change in extracellular concentration of potassium ions affect a cell's membrane potential?
It can cause either depolarization or hyperpolarization, affecting the cell's function.
What is the primary reason for the existence of leak channels in cell membranes?
To enable rapid and significant changes in membrane potential.
How does the Goldman-Katz equation differ from the Nernst equation?
It includes multiple ions to predict membrane potential.
What is the effect of hyperkalemia on membrane potential?
It depolarizes the cell, decreasing the membrane potential.
In the context of membrane potentials, what does the cable model primarily analyze?
The combined effect of ion conductances and equilibrium potentials.
What is the role of the Na-K pump in maintaining the cell's membrane potential?
It maintains ion concentration gradients by pumping Na+ out and K+ in
What is the primary function of the electrogenic effect of the Na-K pump?
To create an electric field that aids in the movement of other ions
How does the cell's membrane potential relate to the intracellular and extracellular ion concentrations?
It depends on the permeability of the membrane to those ions.
What happens to a cell's membrane potential if extracellular potassium concentration increases (hyperkalemia)?
It depolarizes, potentially leading to increased excitability.
What is the role of chloride ions in determining the membrane potential of a cell?
They contribute alongside potassium and sodium ions in determining membrane potential.
What is the effect of the constant field model on understanding membrane potentials?
It simplifies the calculation by assuming a constant electric field across the membrane.
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