Asked in Premeth Test 13 — Reproduction, Support and Movement, Immunity (15 March 2025) 2025Moderate

Which of these processes helps in skeletal muscle relaxation after contraction?

Correct answer: D. None of these

  • A. Motor neurons send electrical signals to muscles
  • B. Troponin binds calcium
  • C. Calcium is released from intracellular storage sites
  • D. None of these

Explanation

Option A: Motor neurons are covered with ion channels, which open in response to electrical signals from the brain. Once these ion channels are open, a series of cascading reactions allows the signal to reach the skeletal muscle cells, which ultimately results in muscle contraction. Option B: Troponin C (TnC) is the calcium-binding subunit of the muscle protein complex troponin. The binding of calcium ions to TnC triggers the contraction of vertebrate striated muscle. Option: C Calcium release from intracellular storage sites plays a central role in the excitation-contraction coupling of striated and smooth muscle cells. It is a function of Calcium in the relaxation and contraction of the muscle.

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About Muscle Contraction

Muscle contraction is explained by the sliding filament model, in which myosin heads pull actin filaments within sarcomeres using ATP. The topic covers calcium, troponin, tropomyosin, the neuromuscular junction and relaxation, with attention to how filament length stays almost constant while the sarcomere shortens.

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