Muscle Physiology- Pt 1 Quiz

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Questions and Answers

What is the primary driving force of movement for uncharged molecules?

Diffusion potential

Electrical charges

Concentration gradient (correct)

Permeability of the membrane

How does the movement of ions due to diffusion potential affect the ion concentration in bulk solutions?

No measurable change (correct)

A complete reversal

A significant increase

A significant decrease

What is the purpose of the equilibrium potential?

To create a membrane potential

To facilitate ion movement

To balance the tendency of ion diffusion (correct)

To generate a diffusion potential

What is the relationship between the concentration gradient and the diffusion potential?

The diffusion potential is dependent on the concentration gradient and the permeability of the membrane Signup and view all the answers

What is the effect of sodium diffusing into a cell on the electrical charge of the cell and its external environment?

The cell becomes more positively charged and the external environment becomes more negatively charged Signup and view all the answers

What is the definition of the membrane potential?

The difference in electrical potential between the interior and exterior of a biological cell Signup and view all the answers

What is the only exception to the membrane potential not varying with time?

Neurons and muscle cells Signup and view all the answers

Which factor has a larger effect on the resting potential of a cell?

The diffusion of potassium Signup and view all the answers

What is the effect of potassium diffusion via potassium leak channels through the nerve cell membrane?

It increases the negative charge within the cell Signup and view all the answers

What is the role of the sodium-potassium pump in nerve cells?

Pump 3 sodium ions out of the cell and pump 2 potassium ions into the cell Signup and view all the answers

What is the primary function of the sodium-potassium pump in maintaining the internal charge of the cell?

To maintain the negative internal charge of the cell Signup and view all the answers

What is the primary reason for the rapid change in membrane potential during an action potential?

The rapid diffusion of sodium ions into the cell Signup and view all the answers

What is the term for the period during which a depolarized area cannot generate another action potential?

Absolute Refractory Period Signup and view all the answers

How does the membrane's permeability differ between potassium and sodium ions?

The membrane is more permeable to potassium than sodium Signup and view all the answers

What is the purpose of the sodium leak channels in the nerve cell membrane?

To allow the diffusion of sodium ions into the cell Signup and view all the answers

What is the net result of the sodium-potassium pump's activity on the internal charge of the cell?

A maintenance of the negative internal charge of the cell Signup and view all the answers

What triggers the beginning of an action potential?

Meeting the threshold voltage Signup and view all the answers

What causes the influx of positive charge during depolarization?

The influx of sodium ions Signup and view all the answers

What happens to the voltage-gated potassium channels during late depolarization?

They open Signup and view all the answers

What occurs during repolarization?

The voltage-gated sodium channels close Signup and view all the answers

What causes the membrane potential to go below the resting membrane potential during hyperpolarization?

The absence of positive sodium ions entering the cell and the continuation of potassium ions exiting Signup and view all the answers

What happens during repolarization?

The membrane returns to its normal negative resting membrane potential Signup and view all the answers

What is the primary requirement for the voltage gated sodium channels to re-open during the absolute refractory period?

The membrane returns to its resting membrane potential Signup and view all the answers

During which stage of the action potential does the relative refractory period take place?

The hyperpolarization stage Signup and view all the answers

What is the minimum membrane potential required for an action potential to be initiated?

-55millivolts Signup and view all the answers

During which period is an action potential completely blocked from being initiated?

The absolute refractory period Signup and view all the answers

What is the membrane potential during the resting stage of the action potential?

-70millivolts Signup and view all the answers

What is the effect of the negative charge of the membrane during the relative refractory period?

It makes it more difficult to initiate an action potential Signup and view all the answers

Study Notes

Membrane Potential

The membrane potential is the difference in electrical potential between the interior and exterior of a biological cell.
It exists across the membrane of all cells and is dependent on the electrical potential of different ions and the permeability of those ions.

Resting Potential

The resting potential is the membrane potential of non-excitable cells or excitable cells that lack excitation.
It is approximately -70 millivolts, but can range between -40 to -90 millivolts.
The -70 millivolt charge refers to the inside of the cell being 70 millivolts more negative than the outside of the cell.
The diffusion of potassium has a larger impact on the resting potential in comparison to sodium.

Ion Movement and Diffusion Potential

Diffusion potential is the charge (potential difference) generated by ions (charge molecules) moving down their concentration gradient.
Uncharged molecules use the concentration gradient for their driving force of movement.
Charged molecules use the concentration gradient in combination with electrical charges for their driving force of movement.
The diffusion potential is dependent on the concentration gradient and the permeability of the membrane.

Equilibrium Potential

Equilibrium potential stops ion movement as it is the diffusion potential that balances the tendency of ion diffusion down its concentration gradient.

Ion Channels and Pumps

Potassium leak channels allow for potassium diffusion out of the cell, resulting in an increased negative charge within the cell.
Sodium leak channels allow for the diffusion of sodium into the cell, causing an increased positive charge within the cell.
The sodium-potassium pump transports 3 sodium ions out of the cell and 2 potassium ions into the cell, maintaining the negative internal charge of the cell.

Action Potential

An action potential is the rapid change in membrane potential that spreads along a nerve fiber membrane until it reaches the nerve fiber's end.
Each action potential starts with a rapid change from the membrane's normal negative resting membrane potential to a positive membrane potential.

Stages of Action Potential

Step 1: Resting Stage - The membrane is at a resting membrane potential of approximately -70 millivolts.
Step 2: Threshold - The membrane reaches a membrane potential of -55 millivolts, achieving threshold.
Step 3: Depolarization - The influx of sodium ions into the cell results in an increased positive charge within the cell.
Step 4: Repolarization - The voltage gated sodium channels close, resulting in an increased negative charge within the cell.
Step 5: Hyperpolarization - The membrane potential goes below the resting membrane potential before eventually returning back to it.

Refractory Periods

Absolute Refractory Period - The time period throughout the entire action potential, excluding the hyperpolarization stage, during which another action potential cannot start.
Relative Refractory Period - The time period during the hyperpolarization stage when an action potential is difficult to achieve, but not impossible.

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Description

This quiz covers the concept of diffusion potential, which is generated by ions moving down their concentration gradient, affecting the electrical charge inside and outside cell membranes.