Skip to Content

Running Off Track

A Case Study in Renal Physiology


Author(s)

Maria-Elena Conin
Department of Biology
Villanova University
Lea C. George
Department of Biology
Villanova University
Joshua D. Kumin
Department of Biology
Villanova University
Philip J. Stephens
Department of Biology
Villanova University
phil.stephens@villanova.edu

Abstract

This interrupted case study follows the course of Cara, a high school athlete training for the state championships in cross country. She suffers from polycystic ovarian syndrome and her prescribed medication (spironolactone) greatly diminishes the action of aldosterone on the distal tubule and the collecting duct of kidney nephrons.  During practice her symptoms of dehydration are complicated by her medication with the result that her extracellular levels of sodium and potassium become imbalanced. As Cara's story develops, students will need to learn and explain the mechanism of aldosterone action on the kidney and her symptoms in terms of ion imbalance and membrane depolarization. This case study was written for use in a one-semester animal physiology course, which is taken by junior and senior science majors; it could also be used in an anatomy and physiology course that covers membrane potentials and the role of aldosterone in ion balance and kidney function.


Objectives

  • Describe the signs and symptoms of dehydration.
  • Describe the action of aldosterone on P-cells in the distal tubule and the collecting duct of kidney nephrons.
  • Explain how an aldosterone receptor antagonist affects the levels of sodium and potassium in the blood.
  • Describe how an aldosterone receptor antagonist can be a diuretic.
  • Calculate the equilibrium potential for potassium using the Nernst equation.
  • Predict how an elevated extracellular level of potassium can depolarize the membrane potential.
  • Explain how membrane depolarization can induce cramping of skeletal muscles.
  • Explain how membrane depolarization can increase heart rate and produce arrhythmias.

Keywords

aldosterone; spirolactone; receptor; nephron; membrane potential; equilibrium potential; potassium; sodium; dehydration

Topical Areas

N/A

Educational Level

Undergraduate lower division, Undergraduate upper division

Format

PDF

Type / Methods

Interrupted

Language

English

Subject Headings

Biology (General)  |   Medicine (General)  |   Physiology  |   Neuroscience  |  


Date Posted

11/25/2016

Teaching Notes

Case teaching notes are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.

Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.

Answer Key

Answer keys for the cases in our collection are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.

Comments