Question

Unstriated muscles are found in
(a) Veins
(b) Arteries
(c) Uterus
(d) All the above

Answer 1

Visceral organs in the body are lined by the muscles that have irregularly arranged actin and myosin fibers and myofibrils do not show dark and light bands.

Complete answer:
Smooth muscles are the unstriated and inventory muscles in the body. Visceral organs like blood vessels, Intestines, stomach, bronchi, kidneys, testis, and ovaries in the body are lined by smooth muscles. smooth muscles are also called visceral muscles. Due to the absence of cross striations, these muscles are called smooth muscles.

Additional information:
- Muscular tissue is mesodermal in origin that shows characteristics like excitability, conductivity, and contractility. They are divided into three types namely skeletal muscles, smooth muscles, and cardiac muscle.
- Striped voluntary muscle that is usually attached to skeletal structures by tendons found in biceps muscles. They are long, cylindrical, and unbranched cells.
- Unstriped, voluntary muscle that is located in the walls of visceral organs are called smooth muscle or visceral muscle. Iris and ciliary muscles of the eye and arrector pili muscles of the skin are also lined by smooth muscle.
- Usually, they are arranged in layers or sheets and it is a spindle-shaped(fusiform), uninucleate cell. Due to the alternate arrangement of actin and myosin filaments, myofibrils do not show dark and light bands.
- They are called inventory muscles because they are not under conscious control.
- Smooth muscles can remain in a contracted state for prolonged periods without fatigue.
- Autonomic nervous system controls smooth muscle contractions

so, the correct answer is 'All the above'

Note: All the muscles are mesodermal in origin except the iris and ciliary body in the eye that are ectodermal in origin. Skeletal muscles show fast contractions and undergo fatigue quickly and they are controlled by the somatic nervous system. The specialized auto-rhythmic structure called the pacemaker produces impulses for contractions of cardiac muscle.