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What transport structure facilitates Ca++ uptake in the sarcoplasmic reticulum?

a) T tubule
b) Myofibril
c) Sarcomere
d) Triad

User Spoonraker
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1 Answer

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Final answer:

The structure that facilities Ca++ uptake in the sarcoplasmic reticulum is the triad, which includes T-tubules and terminal cisternae of the SR.

Step-by-step explanation:

The transport structure that facilitates Ca++ uptake in the sarcoplasmic reticulum (SR) is the triad. The triad is composed of two terminal cisternae (enlarged areas of the SR) and one T-tubule, with the T-tubule sandwiched between the SR membranes. During muscle contraction, action potentials propagate along the sarcolemma and enter the T-tubules, which are narrow invaginations that allow electrical impulses to reach deep inside the muscle fiber near the SR. This triggers the opening of calcium channels in the SR, causing Ca++ to diffuse out of the SR and into the sarcoplasm, initiating the contraction of the muscle by its contractile units, or sarcomeres.

User Vanity
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