Question

Gap junctions have only been identified in which type of muscle?

1) Cardiac muscle
2) Skeletal muscle
3) Smooth muscle
4) All of the above

Answer 1

Gap junctions are found in both cardiac and single-unit smooth muscle to facilitate synchronized contraction, but they are not present in skeletal muscle, which uses neuromuscular junctions for communication. The correct option is 1.

Step-by-step explanation:

Gap junctions are special cellular structures that allow for communication between cells. These structures have been identified in various types of muscle tissue. Specifically, gap junctions have been found to develop in the cardiac and single-unit smooth muscle during the early stages of development, which allows for the synchronized contraction of the heart and certain types of smooth muscle. Unlike cardiac and smooth muscle, skeletal muscle does not typically have gap junctions; instead, skeletal muscle relies on neuromuscular junctions (NMJs) for neural communication and contraction regulation.