Question

In relaxed muscle, Ca₂₊ is found in highest concentration in the

A) sarcoplasm.
B) T tubules.
C) sarcoplasmic reticulum.
D) sarcolemma.
E) neuromuscular junction.

Answer 1

In relaxed muscles, the c. sarcoplasmic reticulum stores the highest concentration of Ca2+ ions, which are essential for triggering muscle contractions.

Step-by-step explanation:

In relaxed muscle, Ca2+ is found in the highest concentration in the sarcoplasmic reticulum. The sarcoplasmic reticulum is a specialized endoplasmic reticulum found in muscle cells, responsible for the storage of calcium ions. These ions are essential for muscle contraction, as they are needed to trigger the coordinated contractions of muscle cells. In the process of muscle contraction, the neurotransmitter acetylcholine initiates an action potential that travels along the sarcolemma and T-tubules, eventually causing the release of Ca2+ from the sarcoplasmic reticulum. This increase in calcium ion concentration in the sarcoplasm triggers the muscle contraction mechanism.