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A “Deafinite” Cause for Alarm

A Case Study in Hearing Physiology



Co Authors:

Rebecca T. Garlinger
Department of Biology
Villanova University

Patrick K. Mitrano-Towers
Department of Biology
Villanova University

Kevin S. Innella
Department of Biology
Villanova University

Philip J. Stephens (rr)
Department of Biology
Villanova University
phil.stephens@villanova.edu

Abstract:

“Henry” is not the best of patients. He has been admitted into the hospital with bacterial pneumonia, but he soon becomes bored and frustrated by his rate of progress; are the prescribed intravenous antibiotics really doing anything? His solution is to take matters into his own hands and increase the rate of antibiotics perfusion with the idea that increasing his dose will cure him faster and hasten his discharge from the hospital. The consequences are not good. During convalescence at home, “Freddie,” Henry’s son, discovers that his father is losing his hearing. In working through this case study, students will discover how sound waves stimulate the hair cells in the cochlea and produce the sensation of hearing. This case was designed for use in a one-semester animal physiology course taken by sophomore and junior science majors; it could also be used in an anatomy and physiology course.

Objectives:
  • Describe how sound entering the ear stimulates hair cells in the cochlea.
  • Explain how movement of the stereocilia changes the membrane potential of the hair cells by opening and closing potassium channels.
  • Describe how changes in the membrane potential change the transmitter output from the hair cells.
  • Explain how changes in the flexibility of the basilar membrane allow frequency discrimination.
  • Identify how damage to hair cells in certain regions of the cochlea can produce tone deafness.
Keywords: Ear; cochlea; hearing; frequency discrimination; stereocilia; potassium channels;
Topical Area: N/A
Educational Level: High school, Undergraduate lower division
Formats: PDF
Type/Method: Interrupted
Language: English
Subject Headings: Biology (General)   Physiology   Medicine (General)   Neuroscience   Zoology  
Date Posted: 7/31/2019
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

Teaching Notes


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Answer Key


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Supplemental Materials


The PowerPresentation below can be used to project two images in the case as described in the teaching notes.

  hair_cells.pptx (~5MB)

Videos

The following video(s) are recommended for use in association with this case study.

   2-Minute Neuroscience:The Cochlea
This video discusses the cochlea. Sound waves pass through the ear and lead to the depression of the oval window, a structure found in the wall of the cochlea. The effect of these movements on sensory elements within the cochlea are described. Running time: 2 min. Produced by Neuroscientifically Challenged, 2015.

  The Hair Cell
This animation (MP4 format, ~4MB) ) illustrates how auditory hair cells detect motion. Running time: 1:39 min. Produced by Phil Stephens, case study co-author.




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