What is the structure and function of smooth muscle?

Answer 1

Smooth muscle is a type of muscle tissue found in the walls of hollow internal organs and structures such as blood vessels, the digestive tract, and the urinary bladder. It is called smooth muscle because its fibers lack the striations (stripes) that are seen in skeletal muscle fibers.

The structure of smooth muscle cells is different from that of skeletal muscle cells. Smooth muscle cells are spindle-shaped and are shorter and narrower than skeletal muscle cells. They have a central nucleus and fewer mitochondria than skeletal muscle cells. There is less organization to the smooth muscle cells compared to skeletal muscle cells, and the cells are connected by gap junctions.

The function of smooth muscle is to provide involuntary contractions of organs and structures. These contractions are slower than those of skeletal muscle and can be sustained for longer periods of time. Smooth muscle is responsible for the movement of food through the digestive tract, the constriction and dilation of blood vessels, and the emptying of the bladder.

Smooth muscle cells have the ability to contract spontaneously, but they can also be stimulated by hormones and neurotransmitters. The contractions are controlled by the autonomic nervous system and are regulated by calcium ions. The contraction of smooth muscle is more energy-efficient compared to skeletal muscle, and it can adapt to changes in the length and tension of the muscle fibers.