PHYSIOLOGY
MUSCLE CONTRACTION
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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All 638 skeletal muscle might relax simultaneously.
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All 638 muscle cells may contract simultaneously.
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Either A or B
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None of the above
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Detailed explanation-1: -A Muscle Contraction Is Triggered When an Action Potential Travels Along the Nerves to the Muscles. Muscle contraction begins when the nervous system generates a signal. The signal, an impulse called an action potential, travels through a type of nerve cell called a motor neuron.
Detailed explanation-2: -During muscle contraction, the I band is reduced in size as the overlap between the thick and thin filaments increases. The Z-lines come together, and so the sarcomere shortens as well.
Detailed explanation-3: -Muscles do not contract in an all-or-nothing way. All of the fibers do not have to contract at the same time, meaning that a muscle can generate a precisely gradated amount of force, coordinated by the dialogue between the nervous system and the muscles.
Detailed explanation-4: -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.