NUTRITION
THE HUMAN BODY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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What two substances are needed for muscles to contract?
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calcium and potassium
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calcium and carbon
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calcium and phosphorus
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calcium and sodium
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Explanation:
Detailed explanation-1: -Calcium diffusing in the cytoplasm between myosin and actin filaments of the muscle fibrils causes the filaments to slide into each other, triggering the contraction of the entire muscle fiber.
Detailed explanation-2: -Vitamin D functions by stimulating intestinal calcium and phosphorus absorption, by stimulating bone calcium mobilization, and by increasing renal reabsorption of calcium in the distal tubule. These functions on bone and possibly kidney, but not intestine, require the parathyroid hormone.
Detailed explanation-3: -Abstract. Calcium triggers contraction by reaction with regulatory proteins that in the absence of calcium prevent interaction of actin and myosin.
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