Question

Cardiac muscle requires junctions that allow electrical signals through. Cardiac muscle also relies on calcium to contract. What junction is involved, and what organelle stores calcium?

A. Gap junctions; Endoplasmic reticulum
B. Synaptic junctions; Lysosomes
C. Tight junctions; Golgi apparatus
D. Desmosomes; Mitochondria

Answer 1

The gap junctions in cardiac muscle cells facilitate the passage of electrical signals, and the sarcoplasmic reticulum is responsible for storing calcium, making A. Gap junctions; Endoplasmic reticulum the correct answer.

Step-by-step explanation:

The junction involved in allowing electrical signals through in cardiac muscle is the gap junction, which forms channels between adjacent cardiac muscle fibers. These allow the quick transmission of action potentials for the coordinated contraction of the heart muscle. The organelle that stores calcium in cardiac muscle cells is the sarcoplasmic reticulum. While cardiac muscle cells do have desmosomes, these structures anchor the ends of the fibers together and are not responsible for the passage of electrical signals. Therefore, the correct answer to the question is A. Gap junctions; Endoplasmic reticulum.