Question

Describe the structure and the function of three types of muscular tissue.

Answer 1

Hint: Muscle tissues are soft and are present along with bone to perform mechanical activities like pushing, pulling, lifting, etc. Muscle cells contain actin and myosin protein filaments, which slide and exhibit contraction that changes the length and shape of the cell.

Complete answer: A muscle tissue is mesodermal in the origin of the embryo but in the case of iris of an eye, myoepithelial cells of salivary glands, mammary glands and sweat glands arise from the ectoderm. It is of three types, namely; skeletal muscles, smooth muscles and cardiac muscles.

1. Skeletal muscles are striated and stripped muscles located in the limbs, body walls, tongue, pharynx and beginning of the oesophagus. They are under the will of an organism. Muscle fibres of these muscles occur in bundles and are attached to the skeleton and each muscle fibre is elongated and surrounded by a delicate thin layer called the sarcolemma. The cytoplasm of fibres is called the sarcoplasm.
2. Smooth muscle tissues are non-striated muscles found in the posterior part of the oesophagus, stomach, intestine, lungs, urogenital tract, urinary bladder, blood vessels, iris of the eye, the dermis of the skin, etc. The structure of these tissues is elongated and spindle-shaped with single oval muscles surrounded by the cytoplasm and absence of the sarcolemma.
3. Cardiac muscles are present in the wall of the heart and the wall of large veins. Each fibre is long and cylindrical and has a definite sarcolemma. The single nucleus is present near the centre.

Note: Muscles are mainly responsible for changing and maintaining the posture, locomotion and movement of an internal organ, like contraction of heart and peristalsis movement of the digestive tract. Skeletal muscles can be consciously controlled, while cardiac and smooth muscles can not be voluntarily controlled.