Question

The cells of single-unit visceral muscle ________?

1) contract all at once
2) are chemically coupled to one another by gap junctions
3) exhibit spontaneous action potentials
4) consist of muscle fibers that are structurally independent of each other

Answer 1

The cells of single-unit visceral muscle are chemically coupled by gap junctions, enabling them to contract as a unified whole, which is necessary for the function of hollow organs they encompass.

Step-by-step explanation:

The cells of single-unit visceral muscle

exhibit a few characteristics:

1. They contract all at once because they are joined by gap junctions.
2. These cells are chemically coupled to one another by gap junctions, allowing synchronized contractions.
3. Single-unit smooth muscle cells exhibit spontaneous action potentials due to their intrinsic properties.
4. They do not consist of muscle fibers that are structurally independent of each other.

The correct answer to the question is that the cells of single-unit visceral muscle are chemically coupled to one another by gap junctions, allowing the entire unit to contract as one. This is because these muscles are found in the walls of hollow organs like the stomach or urinary bladder, which must contract cohesively to function correctly. Importantly, the intertwining of cells through gap junctions optimizes their task of moving substances through the body efficiently, such as food through the digestive tract, thus operating as a synchronously contracting unit.