Question

Uninucleate muscles are present in?

(a) Smooth muscles

(b) Skeletal muscles

(c) Voluntary muscles

(d) All of the above

Answer 1

Hint: Uninucleate muscles are present in a type of muscle used by different systems to exert pressure on vessels and organs. They are involuntary muscles. This type of muscle lacks striation. It is found in hollow organs, such as intestines, uterus, and stomach walls. They are also found in the walls of passages like cardiovascular arteries and veins. 

Complete answer:

Uninucleate muscles have a single nucleus whereas multinucleated muscles have many nuclei.

Smooth muscles are uninucleate and non-striated. It is composed of small spindle- shaped cells with a single, central nucleus. They have unbranched cells that are controlled by the autonomic nervous system. The function of smooth muscle is to contract like any muscle tissue. 

- Smooth muscle consists of smooth muscle cell sheets or chains. These cells have actin and myosin fibers that run through the cell and are supported by another protein framework.

- This type of non- striated involuntary muscle is also present in the urinary, respiratory, and reproductive tracts. Besides that, you will find smooth muscle in the eyes, where it works to change iris size and lens shape. 

- There is also a smooth muscle in the skin that causes hair to rise in response to cold or fear.

- The skeletal muscles and voluntary muscles are multinucleated.

So, the correct answer is, ‘(a) Smooth muscles’.

Note: Smooth muscle, also called involuntary muscle, the muscle under microscopic magnification which shows no cross stripes. The smooth muscle cell is 3- 10 micrometer thick, and 20- 200 micrometer long. Smooth muscle tissue contracts slowly and spontaneously in comparison to striated muscle. It comprises most of the musculature of internal organs and the digestive system.