36) Which of these is a major ifference berwen smooth muscle and skeletal muscle

Question

36) Which of these is a major ifference berwen smooth muscle and skeletal muscle? A) Myosin is the main regulatory protein in smooth muscle. B) Myosin is the main regulatory protein in skeletal muscle. C) Only skeletal muscle has both actin and myosin. D) Only skeletal muscle requires increased calcium ion concentration in the cytosol for contraction. E) Skeletal muscle usually exhibits spontaneous activity, while smooth muscle cannot contract spontaneously 37) Which is a TRUE statement about smooth muscle? A) Changes in cytosolic calcium do not regulate cross-bridge activity in smooth muscle. B) Smooth muscle is striated. C) Smooth muscle does not use troponin-tropomyosin to regulate cross-bridge activity D) The myosin in smooth muscle requires phosphorylation before it can bind to ATP E) Smooth muscle does not have thick and thin filaments 38) Which is a TRUE statement about excitation-contraction coupling? A) Calcium-induced calcium-release plays a role in cardiac muscle cells, as well as in some smooth muscle cells. B) In skeletal muscle cells, excitation-contraction coupling begins when an action potential propagates along the sarcoplasmic reticulum membrane. C) In smooth muscle cells, it must be preceded by an action potential in the cell membrane. D) In skeletal muscle cells, it requires the influx of extracellular calcium ion. E) In all kinds of muscle it requires the entry of calcium from the extracellular fluid 9) Which of the following statements regarding contraction in skeletal and smooth muscle is TRUE? A) In skeletal muscle, calcium ions bind to a regulatory protein on thin filaments; in smooth muscle, calcium ions bind to a regulatory protein on thick filaments B) In skeletal muscle, calcium initiates contractionbybinding to troponin, while in smooth muscle calcium initiates contraction by binding directly to myosin. C) All of the choices are true. D) In skeletal muscle, calcium initiates contraction by binding to troponin, while in smooth muscle calcium initiates contraction by binding to calmodulin. E) In skeletal muscle, calcium initiates contraction by binding to myosin light-chain kinase. while in smooth muscle calcium initiates contraction by binding directly to tropomyosin. 40) Which of the following is FALSE regarding single-unit smooth muscle cells? A) They have an individual neuron innervating of each individual smooth-muscle cell. B) They exhibit tone. C) They may respond to stretch by contracting D) They may have pacemaker activity E) They have many gap junctions between cells.

Explanation / Answer

Answere :

Question 36 : The option (A) is correct i.e. Myosin is the main regulatory protein in smooth muscle.

Question 37 : The option (C) is correct i.e. smooth muscle does not use troponin-tropomyosin to regulate cross bridge activity in smooth muscles.

Question 38 : The option (A) is correct i.e. Calcium-induced calcium-release plays a role in cardiac muscle cells, as well as in some smooth muscle cells.

Question 39 : The option (B) is correct i.e. In skeletal muscle, calcium initiates contraction by binding to troponin, while in smooth muscle calcium initiates contraction by binding to calmodulin.

Question 40 : The option (A) is correct i.e. Single-unit smooth muscle cell do not have individual neuron innervating of each individual smooth muscle cell.

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