Sinh lý tế bào

Play an AI-generated podcast conversation about this lesson

What is the purpose of calculating the equilibrium potential for different ions in a cell?

To determine the concentration gradient of the ions across the cell membrane

To understand the driving force on the ions and how they contribute to the resting membrane potential (correct)

To measure the ionic conductances of the cell membrane

To predict the action potential characteristics of the cell

What is the primary driving force for the net diffusion of uncharged solutes across a cell membrane?

Membrane permeability

Ionic conductance

Electrical potential difference

Concentration difference (correct)

When dealing with charged solutes (ions) across a cell membrane, what two factors must be considered to determine the driving force for net diffusion?

Concentration difference and electrical potential difference (correct)

Resting membrane potential and action potential

Ionic conductance and membrane permeability

Equilibrium potential and ionic current

What is the formula for the driving force on a given ion across a cell membrane?

IX = GX(Em - EX) Signup and view all the answers

Which of the following statements about the resting membrane potential and action potentials is correct?

The resting membrane potential is determined by the combined driving forces of all the ions present Signup and view all the answers

What is the driving force behind the generation of a diffusion potential?

Concentration gradient Signup and view all the answers

If a membrane is impermeable to an ion, what happens to the generation of a diffusion potential?

It stops Signup and view all the answers

What factor determines the magnitude of a diffusion potential?

Charge of the diffusing ion Signup and view all the answers

How do diffusion potentials affect bulk ion concentrations in a solution?

No effect on them Signup and view all the answers

What happens to net diffusion of an ion when it reaches its equilibrium potential?

It stops Signup and view all the answers

What primarily establishes the resting membrane potential?

Ion diffusion potentials Signup and view all the answers

Which ions make the greatest contributions to the resting membrane potential?

K+ and Cl- Signup and view all the answers

What is the typical range of the resting membrane potential in most excitable cells?

-80 to -90 mV Signup and view all the answers

Why is the resting membrane potential close to the equilibrium potentials for K+ and Cl−?

High permeability of K+ and Cl− at rest Signup and view all the answers

How can the contribution of each ion to the membrane potential be evaluated?

Using the chord conductance equation Signup and view all the answers

What is the net driving force on an ion when the actual membrane potential (Em) is more negative than the ion's equilibrium potential (EX)?

The net driving force is negative, and the ion will enter the cell if it is a cation and leave the cell if it is an anion. Signup and view all the answers

What is the relationship between the actual membrane potential (Em) and the ion's equilibrium potential (EX) when the net driving force on the ion is zero?

Em is equal to EX. Signup and view all the answers

How does an ion 'think' the membrane potential is too positive or too negative?

The ion senses the actual membrane potential and compares it to its own equilibrium potential. Signup and view all the answers

What is the direction of ion movement when the net driving force on the ion is positive?

The ion will leave the cell if it is a cation and enter the cell if it is an anion. Signup and view all the answers

What is the purpose of the ion's 'desire' to bring the membrane potential towards its equilibrium potential?

To maintain the resting membrane potential and ensure proper cell function. Signup and view all the answers

What is the primary factor that determines the resting membrane potential of an excitable cell?

The diffusion of ions down their electrochemical gradients Signup and view all the answers

Which of the following statements accurately describes the process of depolarization?

The membrane potential moves towards the equilibrium potential of the most permeable ion Signup and view all the answers

According to the chord conductance equation, which of the following factors does NOT directly contribute to the membrane potential?

The concentration gradient of calcium ions Signup and view all the answers

What is the primary function of action potentials in excitable cells?

To transmit information within the nervous system and muscle cells Signup and view all the answers

Which of the following statements accurately describes the refractory period of an action potential?

It is the period during which the cell is unable to generate another action potential Signup and view all the answers

What happens when two solutions separated by a semipermeable membrane have the same effective osmotic pressure?

They are isotonic Signup and view all the answers

How do ion channels discriminate among ions passing through them?

By the charge of the ions Signup and view all the answers

What does it mean when a solution is described as hypotonic?

It has a lower effective osmotic pressure Signup and view all the answers

When open, what do ion channels permit through them?

Certain ions Signup and view all the answers

In terms of charges, what type of ions do channels lined with negative charges typically permit the passage of?

Cations Signup and view all the answers

How does a potential difference across a membrane affect the diffusion rate of charged solutes?

It can either accelerate or slow down the diffusion rate, depending on the charge of the solute and the direction of the potential difference. Signup and view all the answers

What is the main difference between simple diffusion and facilitated diffusion?

Simple diffusion is a non-selective process, while facilitated diffusion uses membrane carriers and exhibits characteristics like saturation and stereospecificity. Signup and view all the answers

What is a diffusion potential?

A potential difference generated across a membrane when charged solutes diffuse down their concentration gradient. Signup and view all the answers

What happens when the concentration gradient and the charge effect are oriented in the same direction across a membrane?

They combine, resulting in an increased rate of diffusion. Signup and view all the answers

Which of the following statements about facilitated diffusion is correct?

It occurs down an electrochemical potential gradient, just like simple diffusion. Signup and view all the answers

In the context of ion diffusion across cell membranes, what is meant by the term 'electrochemical potential gradient'?

The combined effect of the concentration gradient and the electrical potential difference across the membrane. Signup and view all the answers

Which of the following statements best describes the relationship between diffusion and the resting membrane potential in excitable cells?

The diffusion of ions across the cell membrane is responsible for generating the resting membrane potential. Signup and view all the answers

What is the primary driving force for the net diffusion of charged solutes across a cell membrane?

The electrochemical potential gradient, which is the combined effect of the concentration gradient and the electrical potential difference. Signup and view all the answers

In the context of ion diffusion across cell membranes, what is the significance of the membrane potential?

It contributes to the electrochemical potential gradient, which drives the diffusion of ions. Signup and view all the answers

What is the primary role of facilitated diffusion in excitable cells?

To rapidly transport specific ions down their electrochemical potential gradients during action potentials. Signup and view all the answers