18. What is a motor unit? 19. What is a myogram? Describe the three phases of a twitch contraction. What is the refractory period? 20. Explain: temporal (wave) summation, unfused tetanus, fused tetanus. 21. Explain recruitment (multiple motor unit summation). What drives recruitment? 22. Define muscle tone. 23. Contrast concentric and eccentric isotonic muscle contractions. 24. Where does a muscle get the energy for contraction? 25. Explain how ATP is produced. What implications does this have for muscle function? 26. What is muscle fatigue? What is oxygen debt? 27. How can you increase the force of a muscular contraction? 28. Describe the anatomy and physiology of slow oxidative, fast oxidative and fast glycolytic muscle cells. 29. Explain the anatomy and physiology of cardiac muscle. 30. Explain the anatomy and physiology of smooth muscle. 31. Understand that muscular dystrophies are muscle destroying diseases and that myasthenia gravis is an autoimmune disease in which the body attacks its own acetylcholine receptors.
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What is a motor unit? A motor unit is a single muscle cell that contracts as a unit. Motor units can be found in all types of muscles, including skeletal muscle, cardiac muscle, and smooth muscle. Show more…
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A motor unit is a motor neuron and all the muscle fibers that it controls. A single motor unit may innervate many muscle fibers and can result in constant tension as individual motor neurons cycle between contraction and relaxation. A motor unit is a motor neuron and the muscle fiber that it controls. A single motor unit may innervate only one muscle fiber and can result in constant tension of the muscle. A single muscle fiber may be innervated by multiple motor neurons which result in constant tension as multiple motor neurons cycle between contraction and relaxation. No option is correct. The following is characteristic of aging muscle EXCEPT: Skeletal muscle becomes smaller in diameter Skeletal muscle becomes less elastic due to an increase in fibrous connective tissue Ability to recover from muscular injuries decreases due to decreased number of myosatellite cells Ability to recover from muscular injuries decreases due to increased number of myosatellite cells
Mishal G.
22. Describe the different parts of a motor neuron and their function: cell body, axon, dendrite, and axon terminal. 23. In nerve cells, how are action potentials usually mediated? What convert electrical signals to chemical signals at nerve terminals? What in target cells convert chemical signals back into electrical signals? 24. Name the membrane-enclosed compartments in a eukaryotic cell and their main functions. 25. How are proteins imported into organelles? 26. Understand the signal sequences that direct proteins to the correct compartment. Use ER proteins as examples. 27. How does a soluble protein cross the ER membrane? How does a transmembrane protein anchor itself in the lipid bilayer? 28. Explain the unfolded protein response (UPR). 29. Describe the pathway of exocytosis for secretory proteins. 30. Describe the process of receptor-mediated endocytosis.
Adi S.
6. Describe the order of motor unit recruitment in terms of types of skeletal muscle fibers (slow twitch, fast twitch and intermediate), as force of contraction increases from 5kg to 30 kg, How does the nervous system control this order? 7. As you already know, neurons and muscle fibers both produce electrical impulses (action potentials). But in the introduction of this lab exercise, you were told that the electromyogram cannot distinguish between electricity generated by muscle or nerve tissue. Why can we conclude that almost 100% of the electricity measured by an EMG is coming from the contracting muscles, since the motor neurons must also be firing action potentials for the muscles to contract?
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