1. Write a paragraph of 3-5 sentences describing answering the following questio
ID: 208121 • Letter: 1
Question
1. Write a paragraph of 3-5 sentences describing answering the following question. Your answer should demonstrate your understanding of the physiological concepts underlying the statement and be written professionally. You are curious about why you see people drinking shots of cold brew coffee before they work out. You design an experiment to study the relationship between caffeine and muscle contraction using a living nerve and muscle preparation. You find that adding caffeine to the solution bathing the tissues causes an increase in intracellular Ca2+ concentration in muscle fibers. Based on this finding, what effect do you predict caffeine will have on muscle contraction? Your answer should demonstrate an understanding of the role of Ca2+ in muscle contraction. Assume that ATP levels are sufficient for muscle contraction/relaxationExplanation / Answer
Ca2+ are necessary for muscle contraction. Muscle contracton (skeletal muscle) happens via cross-bridging of myosin heads to the actin. The binding site on actin i.e. myosin head binding site of actin, generally (when in absence of Ca2+) covered by tropomysin, thus myosin cannot bind. A surge in Ca2+ results in binding with troponin causes removal of tropmyosin from myosin binding site of actin and formation of troponin-tropomyosin complex, which in turn results in binding actin and myosin by forming cross-bridges. This initiates a very small shift or sliding of thin filament over thick filament towards the center of sarcomere which is actually a very short range of contraction. Now to continue the process, ATP supplies are required. Given, enough ATP is present (according to question, ATP levels are sufficient), myosin will detach by breaking cross-bridges from the old binding site and re-attaches to a new site (towards the Z disc end of actin filament) by making new cross-bridges. This cross-bridging cycle will continue for muscle contraction as per our requirement or at anatomical limit. Removing Ca2+ ions from sarcomere will results detachment of troponin-tropomyosin complex and tropomyosin covers back the myosin binding site on actin and prevents cross-bridging of actin-myosin head. This results a stop in muscle contraction.
Thus, added caffein, if increasing the intracellular Ca2+ ions, might lead to an ease of muscle contraction as more Ca2+ ions will be available to remove the tropomyosin from myosin binding site of actin, resulting a successful actin-myosin cross-bridging.
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