This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General, Subject name: Physiology
[{'content': 'Type I muscle fibers rich in myosin heavy chain are \nSelect and explain. \nA. Fast contracting, susceptible to fatigue, B. Slow contracting, susceptible to fatigue, C. Fast contracting, resistant to fatigue, D. Slow contracting, resistant to fatigue', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. d (Slow contracting, resistant to fatigue)Two Major Fiber Types: type I and type II fibers Type IType II Slow TwitchFast TwitchMyosin ATPaseLowHighEnergy utilizationLowHighMitochondriaManyFewColorRedWhiteMyoglobinYesNoContraction rateSlowFastDurationProlongedShortResistance to fatigueincreased /morelessEducational points:ProteinLocationComment orjunctionTitinReaches from the Z line to the M lineLargest protein in body. Role in relaxation of muscle.NebulinFrom Z line along length of actin filamentsMay regulate assembly and length of actin filaments.ctr Act in inAnchors actin to Z linesStabilizes actin filaments.DesminLies alongside actin filamentsAttaches to plasma membrane (plasmalemma).DystrophinAttached to plasmalemmaDeficient in Duchenne muscular dystrophy.Mutations of its gene can also cause dilated cardiomyopathy.CalcineurinCytosolA calmodulin-regulated protein phosphatase.May play important roles in cardiac hypertrophy and in regulating amounts of slow and fast twitch muscles.Myosin-binding protein CArranged transversely in sarcomere A-bandsBinds myosin and titin. Plays a role in maintaining the structural integrity of the sarcomere.', 'role': 'assistant'}]