Question

which organelle of the skeletal muscle cell is responsible for releasing stored calcium ions upon electrical stimulation?

a.) sarcolemma

b.) sarcoplasm

c.) sarcoplasmic reticulum (sr)

d.) myofibril

Explanation:

Identify the function of each muscle cell structure

• Sarcolemma: The plasma membrane of a muscle cell, responsible for propagating action potentials.
• Sarcoplasm: The cytoplasm of a muscle cell, containing organelles, glycogen, and myoglobin.
• Sarcoplasmic Reticulum (SR): A specialized smooth endoplasmic reticulum that stores and releases calcium ions (\(\text{Ca}^{2+}\)) upon electrical stimulation.
• Myofibril: A contractile bundle of myofilaments (actin and myosin) within the muscle cell.

Match the organelle to the question prompt

• The question asks for the organelle responsible for releasing stored calcium ions upon electrical stimulation.
• This matches the function of the Sarcoplasmic Reticulum (SR).

Answer:

• a.) Sarcolemma
• b.) Sarcoplasm
• c.) Sarcoplasmic Reticulum (SR) (Correct answer)
• d.) Myofibril