AIPMT-NEET Biology Aspirants, read out the next AIPMT-NEET Biology Study material/ Notes of Muscular Tissue. In this we will learn about types of muscle tissue fiber/cell- smooth, skeletal, cardiac. Important for AIPMT-NEET Biology. Free online notes for AIPMT-NEET.
Muscular tissue consists of elongated cells called as muscle fibres or myocytes. Muscle tissue is responsible for body movements. Myocytes use ATP to generate force for movement. In the whole process, muscular tissue generates heat, which warms the body. Muscles contain special proteins called contractile proteins, which contract and relax to cause movement.
Based on location, structure and function, muscular tissue is classified into 3 types: Skeletal, Smooth and Cardiac.
(1) SKELETAL MUSCLE TISSUE
- Skeletal muscle fibers are long, cylindrical, unbranched, striated, i.e. show striations (alternate light and dark bands visible under light microscope). Also called as Striated muscles.
- These muscle fibers are multinucleated and nucleus lies at the periphery of the fiber.
- These muscles are under voluntary control, i.e. muscles contract or relax by conscious will, e.g. muscles present in limbs. So also called as voluntary muscles.
- These muscle fibers are called as skeletal muscles as they mostly attach to bones by tendons and help in body movement.
- Help in motion, posture, heat production, protection.
(2) SMOOTH MUSCLE TISSUE
- Smooth muscle tissue consists fibers which are small, spindle-shaped (fibers are thick in the middle and tapering at the end), non-striated. These fibers are unstriated/non-striated, so called as smooth muscles.
- These fibers are uninucleated, i.e. have single nucleus in the center of the fiber.
- Smooth muscle fibers control involuntary movements (we cannot start or stop them by our will), like movement of food in the alimentary canal or the contraction and relaxation of blood vessels. So called as involuntary muscles.
- Also found in the iris of the eye, in ureters, wall of G.I. tract (gastro-intestinal tract) and in the bronchi of the lungs.
- Help in involuntary motion, i.e. bloodways, airways, foodways, contraction of urinary bladder and gall bladder.
(3) CARDIAC MUSCLE TISSUE
- Cardiac muscle fibers are cylindrical, branched, striated (like skeletal muscles) and involuntary (like smooth muscles).
- Uninucleated , have one centrally located nucleus.
- These muscles are attached to each other end to end by thickenings of plasma membrane called as intercalated discs, which contain gap junction or desmosomes.
- Present in the heart wall.
- Responsible for rhythmic contraction and relaxation of heart.