MUSCLE NERVE CARTILAGE BONE
SKELETAL MUSCLE
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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excess ATP is stored in the tubules
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calcium ions are released into tubules’ extracellular fluid
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action potentials are conducted through the tubules to the inside of the cell
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ATP is produced in the mitochondria found in the tubules
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Detailed explanation-1: -Action potentials are conducted into the interior of muscle fibers via the T-tubules and there they activate voltage-gated channels known as dihydropyridine receptors (DHPR). Unlike in cardiac muscle, very little calcium enters the muscle fiber from the extracellular space (via the DHPR).
Detailed explanation-2: -Answer and Explanation: The a) T tubules conduct action potentials throughout the interior of the muscle fiber. T tubules, also called transverse tubules, are invaginations of the sarcolemma that travel deep into the muscle fibre.
Detailed explanation-3: -The action potential travels down the t-tubules and excites the sarcoplasmic reticulum which releases calcium. Calcium when bound to troponin causes conformational changes in the sarcomere. Consequently, the interaction of thick and thin filaments of the sarcomere leads to muscle contraction.
Detailed explanation-4: -The transverse tubules (T-tubules) of mammalian cardiac and skeletal muscles are invaginations of the sarcolemma. They play a crucial role in excitation-contraction coupling as well as in intracellular signaling and in regulation of glucose transport.
Detailed explanation-5: -With membranes that contain large concentrations of ion channels, transporters, and pumps, T-tubules permit rapid transmission of the action potential into the cell, and also play an important role in regulating cellular calcium concentration.