Cellular Transport Mechanisms Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What does the Goldman equation calculate regarding cell membranes?

Resting potential based solely on potassium concentration

Membrane potential when three ions are present

Membrane potential involving both positive and negative ions (correct)

Membrane potential exclusively for positive ions

What is the value of the Nernst potential for potassium (K+)?

-70

-94 (correct)

+61 mV

+50 mV

During the initial phase of an action potential, what is the membrane potential changing from?

Equilibrium potential to resting potential

Resting negative potential to positive potential (correct)

Positive potential to resting stage

Zero potential to negative potential

What characterizes the stages of an action potential?

Rapid changes that revert quickly to negative potential Signup and view all the answers

What is the resting membrane potential established by?

The Nernst potential of potassium and sodium ions Signup and view all the answers

What happens to the membrane potential during an action potential?

It experiences a rapid change to a positive potential followed by a return Signup and view all the answers

How does an action potential travel along the nerve fiber?

It jumps from node to node along the fiber Signup and view all the answers

Which ions are primarily involved in establishing the resting membrane potential?

Sodium and potassium Signup and view all the answers

What provides the energy for the co-transport of glucose and sodium ions into the cell?

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

Which statement about the transport protein mentioned is true?

It requires both sodium and glucose to change shape Signup and view all the answers

What type of transport mechanism is exemplified by the sodium co-transport of glucose and amino acids?

Secondary active transport Signup and view all the answers

In what way does the membrane potential differ between extracellular fluid (ECF) and intracellular fluid (ICF)?

ECF contains high sodium and low potassium concentrations Signup and view all the answers

What occurs during endocytosis?

Substances enter the cell Signup and view all the answers

Which of the following best describes the state of sodium ions during the sodium co-transport process?

Sodium ions are high outside the cell and low inside Signup and view all the answers

Which transport mechanism is described as the process of substances exiting the cell?

Exocytosis Signup and view all the answers

Which of the following pairs exemplifies what is being transported during sodium co-transport?

Sodium and Glucose Signup and view all the answers

What role do voltage-gated potassium channels play during action potential?

They increase the rapidity of repolarization. Signup and view all the answers

What happens to the membrane potential during depolarization?

It moves from negative toward zero. Signup and view all the answers

What combined effect speeds up the repolarization process?

Decreased sodium entry and increased potassium exit. Signup and view all the answers

Which channels remain associated with the resting membrane potential?

K+ leak channels. Signup and view all the answers

How quickly does the resting membrane potential recover after an action potential?

Within a few 10,000ths of a second. Signup and view all the answers

What opens the voltage-gated potassium channels?

A rise in membrane potential toward zero. Signup and view all the answers

What is the primary function of the Na+-K+ pump during action potential?

To maintain the concentration gradients of sodium and potassium. Signup and view all the answers

Which statement accurately describes the action potential process?

Both sodium and potassium channels are involved in the process. Signup and view all the answers

What is the conductance of potassium ions relative to sodium ions during the resting state?

50 to 100 times greater for potassium ions Signup and view all the answers

What state is the activation gate of the voltage-gated sodium channels in during the resting stage?

Closed, preventing sodium ion entry Signup and view all the answers

At what millivolts do the activation gates of the sodium channels open?

-70 and -50 millivolts Signup and view all the answers

How soon do sodium channels begin to inactivate after opening during the action potential?

Within a fraction of a millisecond Signup and view all the answers

What initiates the voltage gating of potassium channels during the action potential?

Onset of sodium channel activation Signup and view all the answers

What factor contributes to the disparity in conductance between potassium and sodium ions during resting state?

Greater leakage of potassium ions through leak channels Signup and view all the answers

What is the significance of the action potential to threshold ratio for continued impulse propagation?

It must be greater than 1. Signup and view all the answers

What occurs first at the onset of the action potential?

Sodium channels become activated Signup and view all the answers

What effect does hypocalcemia have on sodium channels?

They become activated with a smaller increase in membrane potential. Signup and view all the answers

How much does sodium conductance increase at the onset of the action potential?

5000-fold Signup and view all the answers

What leads to the initiation of the action potential in a resting nerve fiber?

A disturbance that raises membrane potential significantly above zero. Signup and view all the answers

What phenomenon occurs as a result of spontaneous discharge in peripheral nerves?

Muscle tetany or continuous muscle contraction. Signup and view all the answers

How do calcium channels differ from sodium channels in terms of gating?

Calcium channels are slow channels while sodium channels are fast channels. Signup and view all the answers

What is the role of a positive-feedback cycle in the context of action potentials?

It enhances the inflow of sodium ions, further raising membrane potential. Signup and view all the answers

What happens to the membrane potential if many voltage-gated sodium channels open at once?

Membrane potential rises rapidly. Signup and view all the answers

Which of the following describes the condition when sodium channels exhibit increased permeability?

When there is hypocalcemia. Signup and view all the answers

Study Notes

Transport Mechanisms in Cells

Active Transport: Movement of substances through a cell membrane, often against a concentration gradient.
Secondary Active Transport (Co-Transport):
- Involves symport and antiport mechanisms to transport multiple substances.
- Example: Co-transport of glucose and amino acids with sodium ions.
- Requires sodium concentration gradient (high outside, low inside) to provide energy.

Sodium-Glucose Co-Transport

Sodium and glucose bind to a transporter protein with two sites: one for sodium and one for glucose.
Conformational change occurs only when both bind, allowing transport into the cell.

Vesicular Transport

Endocytosis: Process of engulfing substances into the cell.
Exocytosis: Process of expelling substances from the cell.

Membrane Potential

Electrolyte Concentration:
- Extracellular fluid (ECF) has high sodium (Na+) and low potassium (K+).
- Intracellular fluid (ICF) has the opposite concentration of ions.

Goldman Equation

Used to calculate membrane potential considering the permeability of specific ions: Na+, K+, and Cl−.

Action Potentials

Rapid changes in membrane potential that propagate along nerve fibers.
Initiate from resting membrane potential (-90 mV) to a positive peak and return to a negative state through depolarization and repolarization.

Stages of Action Potential

Resting Stage: Membrane at -90 mV, potassium conductance is significantly higher than sodium.
Depolarization: Rapid entry of sodium ions due to opening of voltage-gated sodium channels.
Repolarization: Sodium channels inactivate and potassium channels open, restoring negative potential.

Voltage-Gated Channels

Potassium Channels: Open slowly after sodium channels, contributing to repolarization by allowing potassium to exit.
Calcium Channels: Slow channels; increase sodium channel permeability in response to low calcium levels, potentially leading to spontaneous nerve firing.

Safety Factor for Propagation

The ratio of action potential to threshold must remain greater than 1 for continued impulse propagation along the nerve fiber.

Positive-Feedback Cycle in Action Potentials

Initial disturbance raises membrane potential, prompting the opening of more sodium channels, leading to a rapid influx of sodium ions and an amplified membrane potential change.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

This quiz focuses on the mechanisms of cellular transport, specifically active transport and secondary active transport. Test your knowledge on how substances move across cell membranes and the role of ions in these processes. Perfect for students studying cellular biology and membrane dynamics.