Given an extracellular [Pi-2] of 4mM and an intracellular [Pi-2] of 40 mM, what is the equilibrium potential of a plasma membrane permeable only to Pi-²?

Human Anatomy & Physiology (11th Edition)
11th Edition
ISBN:9780134580999
Author:Elaine N. Marieb, Katja N. Hoehn
Publisher:Elaine N. Marieb, Katja N. Hoehn
Chapter1: The Human Body: An Orientation
Section: Chapter Questions
Problem 1RQ: The correct sequence of levels forming the structural hierarchy is A. (a) organ, organ system,...
icon
Related questions
Question

I need help please

### Understanding Equilibrium Potential of a Plasma Membrane

**Problem Statement:**
Given an extracellular \([Pi^{-2}]\) of 4mM and an intracellular \([Pi^{-2}]\) of 40 mM, what is the equilibrium potential of a plasma membrane permeable only to \(Pi^{-2}\)?

(Hint— you do *not* need a calculator to solve this question.)

**Answer Options:**
- +305 mV
- -61 mV
- +61 mV
- +30.5 mV
- 0 mV
- -30.5 mV

#### Explanation:

To understand this problem, let's break down the concepts required to find the equilibrium potential.

The equilibrium potential for an ion across a plasma membrane can be determined using the Nernst equation. However, with the hint indicating that a calculator is not needed, this implies that the answer can be derived by logical comparison or an understanding of typical values.

Given:
- **Extracellular \(Pi^{-2}\)**: 4 mM
- **Intracellular \(Pi^{-2}\)**: 40 mM

By noting that intracellular concentration is 10 times higher than the extracellular concentration (*40 mM / 4 mM = 10*), we know from standard chemistry that a tenfold concentration difference typically corresponds to an equilibrium potential shift of around -60 mV, due to the logarithmic nature of the Nernst equation.

Additionally, because the ion in question has a charge of -2, the equilibrium potential will be more negative compared to a monovalent ion. Hence, it will move towards a more negative value consistent with established electrochemical principles.

Among the given options, the most appropriate and equivalent estimate of the equilibrium potential would thus be **-30.5 mV** due to the increased complexity of divalent ions compared to the standard -60 mV seen in monovalent contexts.

Therefore, the correct option is:

- **-30.5 mV**
Transcribed Image Text:### Understanding Equilibrium Potential of a Plasma Membrane **Problem Statement:** Given an extracellular \([Pi^{-2}]\) of 4mM and an intracellular \([Pi^{-2}]\) of 40 mM, what is the equilibrium potential of a plasma membrane permeable only to \(Pi^{-2}\)? (Hint— you do *not* need a calculator to solve this question.) **Answer Options:** - +305 mV - -61 mV - +61 mV - +30.5 mV - 0 mV - -30.5 mV #### Explanation: To understand this problem, let's break down the concepts required to find the equilibrium potential. The equilibrium potential for an ion across a plasma membrane can be determined using the Nernst equation. However, with the hint indicating that a calculator is not needed, this implies that the answer can be derived by logical comparison or an understanding of typical values. Given: - **Extracellular \(Pi^{-2}\)**: 4 mM - **Intracellular \(Pi^{-2}\)**: 40 mM By noting that intracellular concentration is 10 times higher than the extracellular concentration (*40 mM / 4 mM = 10*), we know from standard chemistry that a tenfold concentration difference typically corresponds to an equilibrium potential shift of around -60 mV, due to the logarithmic nature of the Nernst equation. Additionally, because the ion in question has a charge of -2, the equilibrium potential will be more negative compared to a monovalent ion. Hence, it will move towards a more negative value consistent with established electrochemical principles. Among the given options, the most appropriate and equivalent estimate of the equilibrium potential would thus be **-30.5 mV** due to the increased complexity of divalent ions compared to the standard -60 mV seen in monovalent contexts. Therefore, the correct option is: - **-30.5 mV**
Expert Solution
trending now

Trending now

This is a popular solution!

steps

Step by step

Solved in 5 steps

Blurred answer
Similar questions
  • SEE MORE QUESTIONS
Recommended textbooks for you
Human Anatomy & Physiology (11th Edition)
Human Anatomy & Physiology (11th Edition)
Anatomy and Physiology
ISBN:
9780134580999
Author:
Elaine N. Marieb, Katja N. Hoehn
Publisher:
PEARSON
Anatomy & Physiology
Anatomy & Physiology
Anatomy and Physiology
ISBN:
9781259398629
Author:
McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa Stouter
Publisher:
Mcgraw Hill Education,
Human Anatomy
Human Anatomy
Anatomy and Physiology
ISBN:
9780135168059
Author:
Marieb, Elaine Nicpon, Brady, Patricia, Mallatt, Jon
Publisher:
Pearson Education, Inc.,
Anatomy & Physiology: An Integrative Approach
Anatomy & Physiology: An Integrative Approach
Anatomy and Physiology
ISBN:
9780078024283
Author:
Michael McKinley Dr., Valerie O'Loughlin, Theresa Bidle
Publisher:
McGraw-Hill Education
Human Anatomy & Physiology (Marieb, Human Anatomy…
Human Anatomy & Physiology (Marieb, Human Anatomy…
Anatomy and Physiology
ISBN:
9780321927040
Author:
Elaine N. Marieb, Katja Hoehn
Publisher:
PEARSON