case 6

Fluid in the Ear

In this module, you will complete an  interrupted case. This type of case study presents a problem for you to solve in a progressive disclosure format. This format allows you to practice the scientific method from question formulation to hypothesis testing, experimental design, and data analysis and interpretation. You will need to apply knowledge of key terms, concepts, and principles from the textbook, lectures, and your own research in order to solve the case. 

Objectives

1. Illustrate how sound stimulates hair cells in the cochlea.

2. Infer the effects of damage to the vestibular membrane. 

3. Explain how a decrease in the level of potassium bathing the stereocilia can reduce the amount of hair cell depolarization, neurotransmitter secretion, and stimulation of the sensory neurons.

Instructions

1. Download the Hearing, Balance, Taste, and Smell Case Study

 . There are  23 questions (including labeling 2 figures and completing 1 flow chart) on this assignment.

 Type your answers into the PDF or download a Word version of the questions

   or print the assignment, write by hand, and scan back to PDF.

 Upload your completed PDF or completed Word worksheet.

All questions must be answered to earn full credit. Partial work is graded with the posted rubric. Kindly consider using a different color for your answers to help with grading workflow. This case study has 23 required questions including 2 labeled diagrams and 1 flow chart. Name: Part I – What’s Up, Doc? 1. What problems is Julius experiencing? 2. Are any of these problems related? 3. What are some potential causes of these problems? 4. How could Julius’ eating and drinking habits cause or perpetuate his current symptoms? 5. What tests would you run on Julius? What results do you expect? Part II – Don’t Test My Patients 1. What new signs and symptoms is Julius exhibiting? 2. Look at the table above showing a partial list of Julius’ test results. Which results are not within their normal range? 3. What may explain these abnormalities? 4. What is your preliminary diagnosis? 5. If you were the ER physician, what additional tests you would run? For each test predict the result. 6. Paste labeled diagram here. Part III – What Could Possibly Go Wrong? 1. Paste labeled diagram here. 2. Where in the cochlea are the hair cells, the sensory cells that detect sound? 3. What is the function of the stria vascularis, the cells that line the scala media or the cochlea duct? 4. The endolymphatic sac is a blind-ending structure connected to the cochlea and balance organs via the endolymphatic duct (see Figure 2 above). One function of the sac is to secrete endolymph back into the circulatory system. If Julius’ problem is produced by an increase in the pressure of the endolymph, what factors could contribute to an increase in the volume of this fluid? Part IV – Rock On 1. Paste flow diagram here.

2. The ion composition of perilymph is similar to that of interstitial fluid; high sodium and low potassium levels. Dr. Luther stated that Julius’ fall ruptured the vestibular membrane, the membrane between the scala vestibuli and the scala media. What would be the effect of such a rupture on the concentration of the potassium in the endolymph in the scala media, when it mixes with perilymph from the scala vestibuli? 3. What would be the effect of this mixing of endolymph and perilymph on the amount of potassium (and therefore the amount of membrane depolarization) that enters the hair cells when the stereocilia are bent by sound waves? 4. If the number of open voltage-gated calcium channels depends upon the amount of membrane depolarization, what would be the effect of this mixing of endolymph and perilymph on the amount of calcium that enters the hair cells? Further, what would be the effect on the number of vesicles released by the hair cells and the number of action potentials produced in the sensory neurons? 5. What would be the effect of this mixing of endolymph and perilymph on Julius’ hearing? Part V – Recovery 1. The audiogram indicates that Julius has problems hearing certain frequencies. What type of damage may have taken place in Julius’ ear? 2. Would this damage have necessarily taken place in both ears? 3. If you were the doctor, what life style changes would you recommend to Julius?