HSE201 Practice Exam Questions and Correct Answers
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Course
HS201
Institution
HS201
Sarcomere the smallest force-producing unit with a myofibril
Transverse tubule membranous channel extending inward from muscle fiber membrane
Fascia a band or sheet of fibrous connective tissue that covers, supports, and separates muscle
Epimysium a sheath of fibrous elastic tissue surrounding a...
HSE201 Practice Exam Questions and Correct Answers Sarcomere ✅the smallest force -producing unit with a myofibril Transverse tubule ✅membranous channel extending inward from muscle fiber membrane Fascia ✅a band or sheet of fibrous connective tissue that covers, supports, and separates muscle Epimysium ✅a sheath of fibrous elastic tissue surrounding a muscle. Perimysium ✅Connective tissue surrounding a fascicle Endomysium ✅Surrounds individual muscle fibers Sarcolemma ✅muscle cell membrane Sarcomere and force production ✅Sarcomeres consist of actin filaments (thin on the edges) and myosin filaments (thick in the middle). Myosin's are the proteins that generate force and are the only cells that interact and cause cell shortening. This overlapping of proteins enable them to move across one another causing force production. Neuromuscular transmission: ✅1. An action potential arrives at the motor neuron terminal 2. AP opens voltage -gated calcium channels in the motor neuron terminal membrane 3. The calcium influx occurs and then activates migration of vesicles of Ach (the neuron transmitter acetylcholine) to the synapse. 4. Ach is released into synthetic cleft via exocytosis 5. Ach binds to sarcolemmal nicotinic receptors in the motor end plate area 6. Nicotinic AChR's generate an end plate potential via sodium (Na+) influx through the receptor 7. EPP migrates away from motor end plate and then opens voltage gated Na+ channels 8. AP generated in muscle cell. The muscle fibre has been stimulated electrically by a motor neuron and is now active. The skeletal muscle triad ✅consists of a t -tubule flanked by 2 terminal cisternae of the sarcoplasmic reticulum. Provides the site for excitation -contraction coupling Excitation contracting coupling ✅The process of action potential transduction to provide an intracellular signal of an uptake in calcium and subsequent muscle cell contraction The Cross Bridge Cycle ✅1. At rest myosin is energized: ATP has been cleaved to ADP, Pi and energy. Energy is stored within the myosin protein. 2. Ca2+ binds to troponin -C 3. The myosin binding site on actin becomes exposed 4. Myosin becomes bound to actin 5. Pi is released from myosin upon binding with actin 6. Myosin release energy through the power stroke 7. Actin is dragged toward the interior of the sarcomere. This appearance provides the basis of the sliding filament theory 8. Sarcomere length decreases, translating to whole muscle shortening or contraction 9. ADP is released from myosin during the power stroke 10. After power stroke myosin binds a new molecule of ATP 11. Actin and myosin detach 12. ATP hydrolysis occurs to re -energise myosin 13. Myosin head returns to the resting cranked position 14. If a high Ca2+ is maintained 15. Cross bridge cycle continues Summary of muscle contraction ✅1. Neuromuscular transmission via Ach release 2. AP propagation in sarcolemma down t -tubules 3. E-C-Coupling that induces SR Ca2+ release 4. Myosin binding sites exposed 5. Cross bridge cycle = force production 6. Relaxation via active Ca2+ removal 7. Return to resting state 1. Neuromuscular transmission via Ach release 2. AP propagation in sarcolemma down t -tubules 3. E-C-Coupling that induces SR Ca2+ release 4. Myosin binding sites exposed 5. Cross bridge cycle = force production 6. Relaxation via active Ca2+ removal 7. Return to resting state Isotonic ✅Muscle length changes during contraction Concentric ✅Muscle shortens and joint angle decreases Example: the biceps muscle during the lifting phase of a bicep curl Eccentric ✅Muscle lengthens and joint angle increases Example: the triceps muscle during the lifting phase of a bicep curl
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