GMS 6474 Medical Cardiovascular and Muscle Physiology Final Exam Questions & Answers 2024/2025

GMS 6474 Medical Cardiovascular and Muscle Physiology Final Exam Questions & Answers 2024/2025 what does the SR store - ANSWER-proteins and calcium what is the role of the transverse tubules in the muscle fiber - ANSWER-allow inside of muscle to communicate with the outside of the muscle how is a sarcomere measured - ANSWER-from z-disc to z-disc what is contained in the I band of the sarcomere & what color is the band - ANSWER-thin filaments titin z-disc light (isotropic) what is contained in the A band of the sarcomere & what color is the band - ANSWER-thick filaments thin filaments dark (scatters light) what is contained in the H zone & what color is the band - ANSWER-thick filaments light no barbs or myosin middle zone of the sarcomere what is contained in the M line - ANSWER-in the middle of the sarcomere, middle of H zone thick filaments myomesin what does titin do in the sarcomere - ANSWER-structural protein how many zones can you see when the sarcomere is relaxed - ANSWER-all zones can be seen in relaxed state how many zones can be seen when the sarcomere is contracted - ANSWER-sarcomere shortens I band shortens H zone disappears thick and thin filaments overlap DONT shorten what is the contractile unit of skeletal muscle - ANSWER-the sarcomere what is the main component of the thick filaments - ANSWER-myosin have heavy and light chains motor heads that move it along the thin filament what is the largest protein in the body - ANSWER-titin what are the main components of the thin filaments - ANSWER-actin (where myosin binds) troponin (moves tropomyosin when Ca2+ is present) tropomyosin (covers actin active site) nebulin (sets thin filament length) CapZ (anchors actin to Z-line on z-disc side) Tropomodulin (on end of actin, in middle of sarcomere) alpha-actinin (anchors actin to z-line) what does desmin do in the sarcomere - ANSWER-interacts with alpha-actinin to anchor z-disc to sarcolemma what does dystrophin do in the sarcomere - ANSWER-connects sarcomere to sarcolemma stabilizes the sarcolemma to prevent damage during contractions 1st step of cross-bridge cycle - ANSWER-BINDING activated myosin binds to actin ADP and Pi are still bound to myosin 2nd step of cross bridge cycle - ANSWER-POWER STROKE myosin head swivels movement of actin filament ADP and Pi released from myosin (Pi is released first, before ADP is released) 3rd step of cross bridge cycle - ANSWER-DISSOSCIATION ATP binds to myosin Actin and myosin dissociate (cross bridge detaches) 4th step of cross bridge cycle - ANSWER-ACTIVATION ATP hydrolysis energy activates myosin head ADP and Pi remain bound to myosin if Ca2+ still present, cycle continues how does Ca2+ effect the cross-bridge cycle - ANSWER-Ca2+ is needed for the troponin to move the tropomyosin off the actin when Ca2+ runs out, the cross-bridge cycle will stop troponin has 4 Ca2+ binding sites how does Ca2+ get into the cell to trigger the cross-bridge cycle - ANSWER-through the RyR channels, which are activated by the DHPR channel mechanical change IN SKELETAL MUSCLES what are the two roles of ATP in the cross-bridge cycle - ANSWER-release from rigor state re-energize/reactivate myosin heads for next cycle what resequesters Ca2+ to end muscle contraction - ANSWER-SERCA where is the sarcoplasmic reticulum located - ANSWER-wrapped around the sarcomeres and throughout the myofibrils what is the role of the sarcoplasmic reticulum in muscle cells - ANSWER-stores Ca2+ that is needed for contraction what are the components of the triad in the muscle cell - ANSWER-sarcoplasmic reticulum t-tubule what is the role of the triad in the muscle cell - ANSWER-communication center what are the two main receptors in the triad - ANSWER-dihydropyridine receptors (DHPR) ryanodine receptors (RyR) what is the role of the DHPR in the triad - ANSWER-voltage sensor sense when action potential is moving down t-tubule what is the role of the RyR in the triad - ANSWER-Ca2+ release channel what kind of pennate muscle fiber formation has the most force production - ANSWER-multipennate what muscle fiber arrangement is best for speed - ANSWER-when they are stacked on top of each other (like a building) what muscle fiber arrangement is best for strength - ANSWER-when they are next to each other (like a trailer) have more tension what kind of muscle contraction action has the most tension - ANSWER-isometric contraction how many endplates do muscle fibers have - ANSWER-one endplate per muscle fiber continues...