Children with Muscular Disorders
You're doing a clinical rotation with Dr. Barr, a world-renowned specialist in children's muscle disorders. On your first day, you meet three patients with the same probable diagnosis— nemaline myopathy. Jodi, age 2, has a waddling walk and difficulty standing; Linda. 6 months, has pneumonia associated with problems swallowing; and Tom, 12, has progressive weakness with foot drop and difficulty walking.
“This kind of variation is not surprising.” says Dr. Barr. “A mutation in one of 11 different genes related to thin filaments can cause nemaline myopathy, so you’d expect to see it present in different ways.”
Dr. Barr has scheduled all three children for a muscle biopsy (surgical removal of a small piece of muscle tissue for examination). He explains to you. “We’re going to use these biopsies for two things. First, we're going to look for the characteristic histology of nemaline myopathy. Second, we're going to test for malignant hyperthermia. It's not associated with nemaline myopathy but is associated with a different myopathy that has a similar presentation.”
Malignant hyperthermia is caused by a mutation in a gene related to calcium storage and release in skeletal muscle cells. In individuals with malignant hyperthermia, certain anesthetics can trigger a massive release of calcium into the cytoplasm. This leads to the generation of enough heat to substantially raise body temperature—a life-threatening reaction.
5. What is the function of the sarcoplasmic reticulum?
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- A nine-year-old child is brought to the physician by his parents due to clumsiness and multiple falls over the past 4 months. When standing up from a lying position, he crawls onto his knees and slowly walks himself up with his hands. On physical examination there is bilateral calf enlargement. Which of the following features is most likely to be seen on evaluation of a calf biopsy? Answers A-D A Degeneration of muscle fibers with fibrofatty replacement B Necrotic muscle fibers with lymphocyte infiltration C Perivascular inflammation with muscle fiber atrophy D Proliferation of mitochondria within the muscle fibers O O Oarrow_forwardWhether the statement, "Motor neurons trigger action potentials in muscle cell membranes that open voltage-sensitive Ca2+ channels in T tubules, allowing extracellular Ca2+ to enter the cytosol, bind to troponin C, and initiate rapid muscle contraction", is true or false.arrow_forwardThe changes related to muscle mobility are the most obvious in older adult. There can be measurable differences in muscle strength, endurance, range of motion, coordination, elasticity, and flexibility of connective tissue. Regular exercise is necessary to prevent a decrease in muscle strength. Exercise helps to strengthen muscles and keeps joints, tendons, and ligaments more flexible, allowing for a more active lifestyle. Please research and describe some activities you could recommend to an elderly patient to stay active to help them maintain muscle massarrow_forward
- Troponin C has been mutated such that it cannot bind to calcium. Describe the effect of this mutation on sarcomere shortening in skeletal muscle. A complete answer will describe the normal function of troponin C, the normal process of sarcomere shortening, and will describe the overall effect of the mutation on sarcomere shortening based on troponin C's function and its role in the overall process of sarcomere shortening.arrow_forward2) Paula is a scientist who is developing a drug called Fremtol that will be used to treat muscle spasms. This drug acts on specific skeletal muscles to (1) block the release of Ca2+ ions from the sarcoplasmic reticulum, (2) inhibit the pivoting ability of the myosin heads of the thick filaments, and (3) block the production of ATP by the mitochondria in skeletal muscles. By using this drug, contraction of certain skeletal muscle fibers is reduced, which keeps those muscles from producing spasms. In the above scenario, Fremtol’s effect of blocking the release of Ca2+ ions from the sarcoplasmic reticulum would most directly prevent which the following? a. activation of tropomyosin b. activation of troponin c. activation of actin d. All of the above e. None of the abovearrow_forwardDiscuss the notion that intense exercise might result in permanent damage to (b) the musculoskeletal system in children.arrow_forward
- 3) Paula is a scientist who is developing a drug called Fremtol that will be used to treat muscle spasms. This drug acts on specific skeletal muscles to (1) block the release of Ca2+ ions from the sarcoplasmic reticulum, (2) inhibit the pivoting ability of the myosin heads of the thick filaments, and (3) block the production of ATP by the mitochondria in skeletal muscles. By using this drug, contraction of certain skeletal muscle fibers is reduced, which keeps those muscles from producing spasms. In the above scenario, Fremtol’s effect of blocking muscle mitochondrial ATP production would result in the inability of the muscle to make ATP from ___________. a. creatine phosphate b. anaerobic glycolysis c. aerobic respiration d. All of the above e. None of the abovearrow_forwardSelect one muscular system disease or disorder. Write a paragraph explaining the following: 1. What normal functioning of the muscular system does the disorder affect? 2. Does this disorder cause malfunctioning on a molecular level or a macroscopic level or both? How so? 3. Describe the typical patients that are suffering from this disorder? What is a typical treatment protocol and prognosis?arrow_forwardIndicate if the statements are TRUE or FALSE. Statements TRUE FALSE To initiate muscle contraction, calcium ions bind to, and change the shape of the troponin protein molecules which then pull the tropomyosin proteins off the myosin binding sites of the actin helix. An accumulation of lactic acid is the principal cause of sore muscles. During rest, excess oxygen molecules in the sarcoplasm are attracted to a large protein molecule called myoglobin. Anaerobic respiration is the first choice of the muscle cell for the production of ATP.arrow_forward
- Men are generally stronger than women because they typically have larger bodies, and a more significant proportion of their total body mass is made up of muscle. However, when strength is expressed per unit of the cross-sectional area of muscle tissue, men are only 1-2% stronger than women in the upper body and equal to women in the lower body. Explain two factors that explain these disparities.arrow_forwardWhat are the side effects of Muscular dystrophies?arrow_forwardWhat event occurs immediately before the movement of tropomyosin? Initiation of the power stroke Cross bridge formation Active sites on actin are revealed Release of calcium from terminal cisternae Troponin changes shapearrow_forward
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