1-2 Membrane Potential

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Questions and Answers

What is the typical range of resting membrane potential (RMP) in excitable cells?

0 to -20 millivolts (mV)

-70 to -90 millivolts (mV) (correct)

-40 to -60 millivolts (mV)

-90 to -110 millivolts (mV)

How does the sodium-potassium pump contribute to the resting membrane potential?

By pumping 3 Na+ out of the cell and 2 K+ into the cell. (correct)

By pumping 2 Na+ out of the cell and 2 K+ into the cell.

By pumping 3 Na+ into the cell and 2 K+ out.

By contributing a net positive charge to the inside of the cell.

What primarily determines the resting membrane potential?

The membrane's permeability to sodium ions.

The equilibrium potential of sodium ions.

The membrane's permeability to potassium ions. (correct)

The action of chloride ions within the cell.

In the context of the Nernst equation, what does the variable 'z' represent?

The valence (charge) of the ion being calculated. Signup and view all the answers

What is the electrical gradient's role in ion movement across a membrane?

It helps balance the chemical gradient by attracting or repelling ions. Signup and view all the answers

Which ion is primarily responsible for creating a more negative charge inside the cell at rest?

Potassium ions (K+) Signup and view all the answers

What role do chloride ions play in the resting membrane potential?

They help balance the charge by moving inside based on their concentration gradient. Signup and view all the answers

What is the contribution of the sodium-potassium pump to the resting membrane potential in millivolts?

-4 mV Signup and view all the answers

Which statement accurately describes the resting membrane potential?

It is typically closer to potassium's equilibrium potential than sodium's. Signup and view all the answers

What is the primary purpose of the sodium-potassium pump in excitable cells?

To maintain ion concentration gradients across the membrane. Signup and view all the answers

Which ion has a resting equilibrium potential of approximately +60 mV?

Sodium (Na+) Signup and view all the answers

What effect do non-gated potassium leak channels have on the membrane potential?

They enable potassium to leave the cell, enhancing the negative charge inside. Signup and view all the answers

How does the Goldman-Hodgkin-Katz equation differ from the Nernst equation?

The GHK equation considers the permeability of multiple ions. Signup and view all the answers

What is the role of chemical gradients in determining membrane potential?

They drive the movement of ions across the membrane, affecting the potential. Signup and view all the answers

What is the contribution of the sodium-potassium pump considered to be, in terms of membrane potential?

-4 mV each cycle. Signup and view all the answers

What primarily drives ion movement across the cell membrane?

Combination of both chemical gradients and electrical gradients. Signup and view all the answers

Study Notes

Membrane Potential Basics

Membrane potential represents the voltage difference between extracellular fluid and interior of the cell.
Measured with a voltmeter; indicates electric charge variation across the membrane.
Resting membrane potential (RMP) occurs in excitable cells, typically ranging from -70 to -90 mV.

Ion Concentrations and Movements

Sodium (Na+): Predominantly found outside the cell; tends to move inward driven by its concentration gradient.
Potassium (K+): Mostly concentrated inside the cell; tends to exit to balance concentration.
Chloride (Cl-): Higher concentration outside; generally moves into the cell based on gradient.
Ion movements are influenced by both chemical gradients (concentration) and electrical gradients (charge interactions).

Equilibrium Potential (Nernst Equation)

Equilibrium potential indicates the voltage where ion movement due to concentration matches electrical drive.
Potassium equilibrium potential is approximately -90 mV.
Sodium equilibrium potential is around +60 mV.
Calculated through the Nernst equation: ( E = \frac{61}{z} \times \log \left(\frac{[ion]{out}}{[ion]{in}}\right) ), where z is the ion's charge.

Resting Membrane Potential

RMP is close to potassium's equilibrium potential (~-90 mV) due to higher permeability to K+ when at rest.
The Goldman-Hodgkin-Katz (GHK) equation incorporates multiple ions (K+, Na+, Cl-) to account for their combined effects on membrane potential.

Potassium Leak Channels and Sodium-Potassium Pump

Non-gated K+ leak channels allow potassium efflux, enhancing the negativity inside the cell.
The sodium-potassium pump actively maintains concentration gradients by exporting 3 Na+ ions and importing 2 K+ ions.
This pump is electrogenic, contributing approximately -4 mV to the resting membrane potential due to unequal ion movement.

Testable Concepts

Understand concepts of resting membrane potential along with the roles of sodium and potassium ions.
Familiarity with equilibrium potential and application of the Nernst equation for ion-specific calculations is essential.
Comprehend the effect of ion permeability on membrane potential; greater K+ permeability results in a potential closer to -90 mV.
Recognize the functions of leak channels and the sodium-potassium pump in maintaining the resting potential.
Explore the relationship between alterations in ion concentration and shifts in membrane voltage.
Grasping these principles of membrane potential is vital for pharmacology, especially regarding drug interactions with ion channels, and for physiological understanding in pharmacy education.

Membrane Potential Basics

Membrane potential represents the voltage difference between extracellular fluid and interior of the cell.
Measured with a voltmeter; indicates electric charge variation across the membrane.
Resting membrane potential (RMP) occurs in excitable cells, typically ranging from -70 to -90 mV.

Ion Concentrations and Movements

Sodium (Na+): Predominantly found outside the cell; tends to move inward driven by its concentration gradient.
Potassium (K+): Mostly concentrated inside the cell; tends to exit to balance concentration.
Chloride (Cl-): Higher concentration outside; generally moves into the cell based on gradient.
Ion movements are influenced by both chemical gradients (concentration) and electrical gradients (charge interactions).

Equilibrium Potential (Nernst Equation)

Equilibrium potential indicates the voltage where ion movement due to concentration matches electrical drive.
Potassium equilibrium potential is approximately -90 mV.
Sodium equilibrium potential is around +60 mV.
Calculated through the Nernst equation: ( E = \frac{61}{z} \times \log \left(\frac{[ion]{out}}{[ion]{in}}\right) ), where z is the ion's charge.

Resting Membrane Potential

RMP is close to potassium's equilibrium potential (~-90 mV) due to higher permeability to K+ when at rest.
The Goldman-Hodgkin-Katz (GHK) equation incorporates multiple ions (K+, Na+, Cl-) to account for their combined effects on membrane potential.

Potassium Leak Channels and Sodium-Potassium Pump

Non-gated K+ leak channels allow potassium efflux, enhancing the negativity inside the cell.
The sodium-potassium pump actively maintains concentration gradients by exporting 3 Na+ ions and importing 2 K+ ions.
This pump is electrogenic, contributing approximately -4 mV to the resting membrane potential due to unequal ion movement.

Testable Concepts

Understand concepts of resting membrane potential along with the roles of sodium and potassium ions.
Familiarity with equilibrium potential and application of the Nernst equation for ion-specific calculations is essential.
Comprehend the effect of ion permeability on membrane potential; greater K+ permeability results in a potential closer to -90 mV.
Recognize the functions of leak channels and the sodium-potassium pump in maintaining the resting potential.
Explore the relationship between alterations in ion concentration and shifts in membrane voltage.
Grasping these principles of membrane potential is vital for pharmacology, especially regarding drug interactions with ion channels, and for physiological understanding in pharmacy education.

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Description

This quiz covers the fundamental concepts of membrane potential, specifically tailored for pharmacy students. Learn about the basics of voltage differences, resting membrane potential, and the role of ions. Test your knowledge on the key points that define how cells maintain their electrical charge.