13) An infection by the bacterium Clostridium tetani can cause the disease called A) cholera.B) polio.C) botulism.D) tetanus.E) muscular dystrophy.Answer: DLearning Outcome: 10-4Bloom's Taxonomy: Knowledge14) A single contraction-relaxation cycle in a muscle fiber produces a(n) 15) A muscle produces its highest tension when in complete 16) Identify the incorrect statement about a single motor unit.
1) Describe the basic sequence of events that occurs as an action potential arrives at the neuromuscular junction and is transmitted to the muscle cell.Answer: The action potential triggers the exocytosis of neurotransmitters stored in vesicles in the axon terminal. This acetylcholine binds to receptors in the motor end plate, increasing the muscle membrane permeability to sodium. Acetylcholinesterase destroys the acetylcholine, ensuring that each nerve action potential produces only a single twitch. The influx of these positive sodium ions triggers an action potential. The action potential spreads in both directions away from the motor end plate across the entire surface of the muscle fiber and into the interior via transverse tubules, triggering a pulse of calcium ion release from the sarcoplasmic reticulum, which generates a brief small twitch. With additional stimuli, calcium ion builds up and higher tensions are produced.Learning Outcome: 10-4Bloom's Taxonomy: Comprehension2) A hypothetical genetic disease causes the body to produce antibodies that compete with acetylcholine for receptors on the motor end plate. Patients with this disease exhibit varying degrees of muscle weakness in the affected muscles. If you could administer a drug that inhibits acetylcholinesterase or a drug that blocks acetylcholine, which one would you use to alleviate these symptoms? Answer: This is a case of competition between acetylcholine and the antibody. To make the patient's acetylcholine more effective, a drug that inhibits acetylcholinesterase would slow the breakdown of acetylcholine, relieving some of the weakness. An acetylcholine blocker would be worse than doing nothing.
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