Soru
11. Which of the following is true regarding the smooth muscle? A) Unitary or Multiunit smooth muscle B) Contains acti n and myosin filaments C) Varicos ities instead junction D) Ca2+ enters from the extracellular fluid E) All of above
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4.2
(228 Oylar)
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Elit · 8 yıl öğretmeni
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The correct answer is B) Contains actin and myosin filaments.Smooth muscle is a type of muscle tissue found in the walls of hollow organs, such as the intestines, blood vessels, and bladder. It is different from skeletal muscle in its structure and function.Option A) Unitary or Multiunit smooth muscle: This is true. Smooth muscle can be classified into two types: unitary (or single-unit) smooth muscle and multiunit smooth muscle. Unitary smooth muscle cells are connected by intercellular junctions called gap junctions, allowing for coordinated contractions. Multiunit smooth muscle cells, on the other hand, function independently and are not connected by gap junctions.Option B) Contains actin and myosin filaments: This is true. Smooth muscle cells contain actin and myosin filaments, which are responsible for muscle contraction. However, the arrangement of these filaments is different in smooth muscle compared to skeletal muscle.Option C) Varicosities instead junction: This is true. In smooth muscle, the release of neurotransmitters occurs at specialized structures called varicosities, rather than at discrete junctions as in skeletal muscle.Option D) Ca2+ enters from the extracellular fluid: This is true. In smooth muscle, calcium ions (Ca2+) can enter the cell from the extracellular fluid, leading to muscle contraction. This is different from skeletal muscle, where calcium ions are released from the sarcoplasmic reticulum within the muscle cell.Option E) All of above: This is true. All the statements mentioned in options A, B, C, and D are true regarding smooth muscle.Therefore, the correct answer is B) Contains actin and myosin filaments.