You perform a laboratory experiment where you place a piece ofskeletal muscle in

Question

You perform a laboratory experiment where you place a piece ofskeletal muscle in a calcium-free medium. What would happen if youdepolarize the muscle membrane? What would happen if you depolarizethe somatic motor neuron innervating the muscle? (2 marks) Next you repeat the experimentsfrom Question 6 with a piece of smooth muscle, but this time testthe muscle tissue over a much more sustained period of time. Wouldyou get the same results as with the skeletal muscle? Explain youranswers. (2 marks) Please give a full-detailed explanation. Will rate well. You perform a laboratory experiment where you place a piece ofskeletal muscle in a calcium-free medium. What would happen if youdepolarize the muscle membrane? What would happen if you depolarizethe somatic motor neuron innervating the muscle? (2 marks) Next you repeat the experimentsfrom Question 6 with a piece of smooth muscle, but this time testthe muscle tissue over a much more sustained period of time. Wouldyou get the same results as with the skeletal muscle? Explain youranswers. (2 marks) Please give a full-detailed explanation. Will rate well. Please give a full-detailed explanation. Will rate well.

Explanation / Answer

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•An action potentialreaches the axon of the motor neuron.

•Theaction potential activates voltage gated calcium ion channels onthe axon, and calcium rushes in.

•Thecalcium causes acetylcholine vesicles in the axon to fuse with themembrane, releasing the acetylcholine into the cleft between theaxon and the motor end plate of the muscle fiber.

•The skeletal muscle fiberis excited my large mylenated nerve fibers which attach to the

neuromuscularjunction. There is one neuromuscular junction for eachfiber.

•The acetylcholine diffuses acrossthe cleft and binds to nicotinic receptors on the motor end plate,opening channels in the membrane for sodium and potassium. Sodiumrushes in, and potassium rushes out. However, because sodium ismore permeable, the muscle fiber membrane becomes more positivelycharged, triggering an action potential.

•The action potential on the musclefiber causes the sarcoplasmic reticulum to release calciumions(Ca++).

•

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