Anatomy & Physiology A Case on Nervous Tissue

1. As mentioned in the case description, tetrodotoxin is a molecule that blocks voltage-gated sodium ion channels. What is a voltage-gated sodium ion channel and what is its function? 2. When nerve cells are at rest, there is an unequal amount of positive and negative charges on either side of a nerve cell membrane. This charge difference creates an electrical potential. Describe how the resting membrane potential (resting potential) is generated. 3. What is happening to the electrical potential of a neuron when it generates an action potential? What is the function of the action potential in neurons? 4. Describe the role of sodium ions and sodium channels in generating an action potential. 5. What would happen to a neuron if it was exposed to tetrodotoxin? Be specific regarding its effect on the ability of a neuron to communicate. Discussion Case Study Questions 6. Now that you have addressed some of the basic biology of this case, explain why Dr. Westwood experienced numbness after eating the puffer fish meal. 7. Paralysis is a term used to describe the loss of muscle function. If tetrodotoxin’s effect is on neurons, why did Dr. Westwood experience paralysis? 8. Define the following phrases and terms associated with the signs and symptoms of Dr. Westwood’s TTX poisoning. Develop a table and place it at the end of your paper before your references with all of this information. Please use these terms or the definition of these terms in your paper. diaphoresis motor dysfunction paresthesias cyanotic hypoventilating bradycardia gastric lavage oxygen saturation Bad Fish: A Case on Nervous Tissue One evening during a recent trip to Indonesia, Dr. Marshall Westwood sat down to a meal of puffer fish and rice. Within an hour of returning to his hotel room, Dr. Westwood felt numbness in his lips and tongue, which quickly spread to his face and neck. Before he could call the front desk, he began to feel pains in his stomach and throat, which produced feelings of nausea and eventually severe vomiting. Fearing that he had eaten some “bad fish” for dinner, Dr. Westwood called a local hospital to describe his condition. The numbness in his lips and face made it almost impossible for him to communicate, but the hospital staff managed to at least understand the address he gave them and they sent an ambulance. As Dr. Westwood was rushed to the hospital, his breathing became increasingly labored. The patient presented in the ED with diaphoresis, motor dysfunction, paresthesias, nausea, and an ascending paralysis that started in his legs and spread to the upper body, arms, face, and head. The patient was cyanotic and hypoventilating. Within 30 minutes of presenting in the ED, Dr. Westwood developed bradycardia with a BP of 90/50 mmHg. Atropine was administered in response to the bradycardia. Intravenous hydration, gastric lavage, and activated charcoal followed a presumptive diagnosis of tetrodotoxin poisoning that was based on the clinical presentation in the ED. Five hours after treatment, the following vital signs were noted: • BP 125/79 mmHg • HR 78 bpm • Oxygen saturation: 97% on room air After discussing his case with his physician, he learned that he had probably been the victim of puffer fish poisoning. The active toxin in the tissues of this fish is a chemical called tetrodotoxin (TTX). Tetrodotoxin is in a class of chemicals known as neurotoxins because it exerts its effects on neurons. The specific action of tetrodotoxin is that it blocks voltage-gated sodium ion channels. Background Case Study Questions 1. As mentioned in the case description, tetrodotoxin is a molecule that blocks voltage-gated sodium ion channels. What is a voltage-gated sodium ion channel and what is its function? 2. When nerve cells are at rest, there is an unequal amount of positive and negative charges on either side of a nerve cell membrane. This charge difference creates an electrical potential. Describe how the resting membrane potential (resting potential) is generated. 3. What is happening to the electrical potential of a neuron when it generates an action potential? What is the function of the action potential in neurons? 4. Describe the role of sodium ions and sodium channels in generating an action potential. 5. What would happen to a neuron if it was exposed to tetrodotoxin? Be specific regarding its effect on the ability of a neuron to communicate. Discussion Case Study Questions 6. Now that you have addressed some of the basic biology of this case, explain why Dr. Westwood experienced numbness after eating the puffer fish meal. 7. Paralysis is a term used to describe the loss of muscle function. If tetrodotoxin’s effect is on neurons, why did Dr. Westwood experience paralysis? 8. Define the following phrases and terms associated with the signs and symptoms of Dr. Westwood’s TTX poisoning. Develop a table and place it at the end of your paper before your references with all of this information. Please use these terms or the definition of these terms in your paper. diaphoresis motor dysfunction paresthesias cyanotic hypoventilating bradycardia gastric lavage oxygen saturation 1 Case Study Guidelines Primary Goals of Case Study Report o Analyze case studies that illuminate important concepts of human anatomy and physiology. o Address real-life situations by using knowledge that is gained while studying human anatomy and physiology. o Provide an appropriately written interpretation of the case study, giving background information and responses to questions asked. Format o This is an independent assignment, not a collaborative assignment. o Typed: 12 point Times New Roman o Single-spaced. o Maximum 1” margins on all four sides. o The body of the case study report, not including the title page, should be no more than four pages long. o All sections should be headed with a title that is capitalized, in boldface type, and underlined on its own line in the text with a single line space above and below. (See below for required sections) o All paragraphs should be indented without line gaps in between, except after a section heading. o Include page numbers on bottom right. o All sources must be appropriately referenced. o Correct grammar, spelling and sentence structure are a must. (Writing Center: Information on My CCA - Academic Support - Tutoring Service - Tutoring Schedule - Writing Studio – Centre Tech and Lowry - then Writing Studio sign-up) o Submitted to D2L drop box as .doc or similar file type where a plagiarism detector program will be run o Some guidelines borrowed and adapted from: http://www.writing.engr.psu.edu/workbooks/laboratory.html#results (2011); Cliff, W.H., & Wright, A. W. Directed case study method for teaching human anatomy and physiology. Advances in Physiology Education. 1996; 15: S19-S28. What the student report will include is below: Case Study Title Page The title page should contain the Title of Case Study in the center of the page, Student name, the Course Number (including section), and the Date. Summary of Case Study The case summary should briefly summarize the case given to you. Only the pertinent points from the case study will be included in this section. The summary should be in your own words and should not contain any material directly quoted from the case itself. 2 Background of case study disease Background information about the disease presented in this case study will be included in this section. The background information should contribute to understanding the disease and the importance of this understanding. Write this information as if you were communicating to another student who has not yet covered this subject. Material presented here would include, but is NOT limited to potential causes of the disease (etiology), factors that may have contributed to the advancement of the disease in the subject of the case (risk factors) and signs and symptoms of the disease. The material in this section will go BEYOND what is presented in the original case itself. You will have to do outside research to complete this section. Discussion of Case Study Questions In this section you will go beyond the simple reporting of the case study and background information. This section provides you with the opportunity to answer all the questions provided with the case study to increase understanding. This information will be narrative paragraphs that should flow from answer to answer. Do not simply answer one question after another; tie them together in paragraphs; in this way, answers to multiple questions may be included in a single paragraph. This section should include a statement of how you, the student, see yourself using the information from this case study in the future.