Case MS Wearing Nerves AP1 PDF

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“Wearing on Her Nerves” Case study

Case Study Instructions: 1.

Read the “Wearing on Her Nerves” case study PDF document posted as a PDF in Canvas. Please read only one part of the case study at a time, then answer the associated questions in this document before going on to the next part of the case study.

2.

Read and type into this document your answers, then print the document. If it is more than one page staple together pages. Hand the completed document in as a printed hardcopy on the due date.

3.

Be sure to put everything into your own words. This is to allow you to avoid plagiarism, which would mean using the answers from another group or from answer keys you may otherwise obtain. I may do checks on the web to confirm that the work is your own, please make sure it is. Plagiarism could result in a zero on this assignment and is reported to the Dean of Academic Affairs’ office. Cite the source of all information if not from the case study document(s) or the textbook, but where possible put information into your own words.

4.

To answer the questions in this document you will need to use information from the textbook chapter on the nervous system. For additional information about multiple sclerosis you will need to see the National MS society website at: http://www.nationalmssociety.org/ and/or other reputable sites such as at medical schools or university sites to research topics covered (i.e., signs/symptoms & treatment).

5.

Please split up into groups of ~4 students (generally your lab table group) from your section to do this assignment. Each group will hand in a single answer sheet which must contain all group member names. However, all group members should be familiar with all questions/answers since I may call on any of you during the in-class discussion, and because this material may be on the exam.

6.

If someone in your group, after repeated attempts to include them, does not participate in this assignment you have the option of not including their name on the assignment. You must notify them about this at least two days before this is due since they will need to hand in their own assignment, due the same day.

Grading: 20 points – Did as a group, typed/printed/stapled, proper citations. 80 points – questions. Note: Late submissions past the due date may not be accepted. Part I Questions: 1. What components of the nervous system are involved in physical sensation? How do sensory impulses move throughout the body? (5 points) Both the CNS and the PNS are involved in physical sensation. The brain and spinal cord, which form part of the nervous system, are also involved in physical sensation. Sensory impulses travel throughout the body along a neuron, which can be compared to an electric charge. After being stimulated by a receptor in the skin, and passed along to a sensory neuron, it then travels through afferent fibers making its way to the spinal cord and finally to the brain. 2. What components of the nervous system are involved in skeletal muscle movement? How do motor impulses move throughout the body? What is a “motor unit”? (5 points) The PNS is involved in skeletal muscle movement, specifically, the motor division. As opposed to sensory impulses, motor impulses travel through efferent fibers. A motor unit refers to a motor unit and it is connected muscle fibers.

3. Starting from the release of acetylcholine by the motor neuron, what are the steps in muscle contraction? Give these in detail (potential essay question on exam). (10 points) 1. The distal end of a motor neuron releases acetylcholine 2. Acetylcholine diffuses across the gap at neuromuscular junction binding to receptors on the muscle fiber membranes 3. The muscle fiber membrane is stimulated, and a muscle impulse travels deep into the fiber through the transverse tubules and reaches the sarcoplasmic reticulum 4. Calcium ions diffuse from the sarcoplasmic reticulum into the sarcoplasm and bind to troponin sites 5. Troponin and tropomyosin interact to expose binding sites on actin 6. Actin and myosin filaments form linkages 7. Myosin cross-bridges pull actin filaments inward 8. The muscle fiber shortens as a contraction occurs 4. Are Kathy’s medical problems related to her sensory neurons, motor neurons, or both? What in Kathy’s medical history supports your answer? (10 points) Kathy’s medical problems are related to both her sensory and motor neurons. Her sensory neurons are responsible for the numbness and tingling. Sensory neurons aren’t limited to physical sensation, they are also involved in taste, hearing, vision and temperature, this can also explains why she had reported a temporary loss of hearing. Additionally, she stated that she had scraped her knee and didn’t feel any pain, which also supports that her issues are related to her sensory neurons. She also reported muscle weakness and inability to get out of bed and walk properly, thus not having full control of her legs, these symptoms would be related to her motor neurons which are the ones responsible for activating muscle cells to cause movement. Part II Questions: 5. What is myelin? Describe how it affects the transmission of nerve impulses? Identify the cells responsible for the formation of myelin. (10 points) Myelin is a protective covering of the axons made of proteins and fatty acids. It affects the transmission of nerve impulses by speeding up the impulses to move more quickly and efficiently along the axon. 6. How does the presence of absence of myelin sheaths covering an axon affect action potential propagation (transmission along the axon) in normal, undamaged nerves? (10 points) The main function of myelin is to protect and insulate axons, which enhances their transmission of electrical impulses, or in a more technical form: it’s known to increase the velocity of impulse transmission. When myelin is damaged, impulse transmission is slowed down, this can be seen in neurological conditions such as multiple sclerosis. For example, when the axon is coated with a myelin sheath, the velocity of impulse transmission is increased, allowing for an action potential to travel the length of the axon rapidly and stimulate muscle contraction, resulting in coordinated movements such as running possible. On the other hand, without myelin the velocity would be decreased, making for running as well as other movements involving coordination impossible. 7. What are the “scleroses” in Multiple Sclerosis and why do they occur? How does this influence nerve transmission? (5 points) Multiple sclerosis [the name] refers to the scars (scleroses) on the myelin sheaths. The scarring causes a number a symptoms that vary depending on which signals are affected. 8. Why did steroids help alleviate Kathy’s symptoms? – Give at least two reasons (5 points) 1. Steroids reduce swelling and inflammation, which is why it may help alleviate some of the symptoms in MS patients as it alleviates some of the swelling in lesions caused by MS. 2. Also, Steroids decrease antibody production of the immune system. That is to say that if a certain “bad” antibody is a work, steroids may bring the patient out of the attack quickly.

However, steroids are only taken for a short period of time to help symptoms, they do not help in treating the long-term outcome of MS. 9. How does Copaxone work as treatment for Multiple Sclerosis? What are some other types of medications and how do they differ from Copaxone? (10 points) According to multiplesclerosisnews.com Copaxone is a small synthetic protein, made to mimic a fragment of myelin. It consists of four amino acids, the building blocks of proteins, that are found in myelin. The exact mechanism of how Copaxone reduces the frequency of relapses in RRMS is not known, but it is thought that the medicine modifies the immune response against myelin. For example, Copaxone may act to increase the immune system’s tolerance to myelin through repeated exposure, in a similar way to a vaccine. Another mechanism could be that Copaxone may alter which immune cells are active; it may be able to induce a type of immune cells called suppressor T-cells that secrete anti-inflammatory proteins and prevent damage. Copaxone may also act to prevent the activation of T-cells that target and attack myelin. While Copaxone can reduce the rate of relapses and slow the progression of MS, it cannot reverse or cure the disease. Some other commonly used medications for multiple sclerosis are Avonex, Betaseron, Extavia, Plegridy, and Rebif, however this is just a few out of a large number of other used medications for MS. Despite being administered in injection form, these medications differ not only by the area of injection but also by the way they are made and how they affect the body. For example, Copaxone is a man-made protein. It may prevent certain white blood cells (T cells) from damaging myelin. Administered once daily. Avonex on the other hand, is what is known as an interferon. It is injected once per month into a major muscle. Interferons are chemical messengers that help regulate your immune response and prevent your body from attacking your central nervous system. 10. Why did Kathy experience the altered sensation in her lower body? Was there something wrong with her skin? Why couldn’t she stand? Was there something wrong with the muscles of her right leg? (10 points) According to National Multiple Sclerosis Society, MS is an abnormal “immune-mediated response that causes inflammation and damage to the myelin coating wrapped around nerve fibers (axons) in the CNS” (NMSS 2018) This means that Kathy’s very own body’s immune cells, target her CNS. Kathy experienced a numbness or weakness in her limb due to the location of the affected nerve fibers. According to the National Institute of Neurological Disorders and Stroke, some symptoms that can occur, which Kathy has experienced was the numbness and tingling sensation (which has spread up to her knees), inability for her right leg to properly engage, which is not due to muscular function but nervous tissue damage (NINDS 2017). Multiple Sclerosis causes this demyelination of the myelin sheath, affecting that specific area of her lower extremity. This symptom accounts for lack of coordination of the body and weakness. 11. Did Kathy’s hearing loss have anything to do with the Multiple Sclerosis? Explain. (10 points) extra credit This infectious factor may have been a big factor in the onset of her Multiple Sclerosis. According to Kathy’s memory, her lost of hearing earlier in the year was caused by severe inner ear infection (which could have destroyed her ability to hear on that side). Research from NMSS show that many viruses and bacteria such as that of measles, EBV, chlamydia pneumonia, etc. have been investigated to determine if they are involved in the development of MS. This severe infection could have triggered an immune response, which later developed into the release of specific immune cells that is a major cause of demyelination and Multiple Sclerosis.

Citations (books, journal articles, or other resources you used to answer the questions): Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition. New York: W. H. Freeman; 2000. Section 21.2, The Action Potential and Conduction of Electric Impulses.Available from: https://www.ncbi.nlm.nih.gov/books/NBK21668/

https://familydoctor.org/condition/multiple-sclerosis/ https://www.healthline.com/health/copaxone-vs-avonex#differences https://multiplesclerosisnewstoday.com/copaxone-multiple-sclerosis/ https://psych.athabascau.ca/html/Psych289/Biotutorials/1/myelin.shtml https://www.nationalmssociety.org/ https://www.ninds.nih.gov/Disorders/All-Disorders/Multiple-Sclerosis-Information-Page https://www.news-medical.net/health/Myelin-Function.aspx...