Muscular Tissues Department of Biology

Introduction These tissue form the muscle of the body. Composed of muscle cells or muscle fibers (contraction and relaxation). Most of their cytoplasm modified into contractile threads (Myofibrils). Special terms: Sarcolemma= plasma membrane, Sarcopalsm= cytoplasm, Sarcopalsmic reticulum=E.R.

Smooth Muscle Composed of elongated, fusiform - muscle cell with a single central nucleus. Continuous contraction

Smooth Muscle They contract in a similar pattern to skeletal muscle but the myofibrils are scattered in sarcoplasm overlapping each other and no striations. Involuntary Found in blood vessels walls, viscera (intestine, uterus, urethras)

Skeletal Muscle Skeletal muscle are responsible for movement of the skeleton and organs as the globe of the eye and the tongue. Voluntary muscle.

Skeletal Muscle Composed of bundles of very long cylindrical multi- nucleated cells (muscle fibers). The nuclei periphery of cell under the sarcolemma. A syncytium.

Skeletal Muscle The sarcoplasm contains longitudinal fibrils (myofibrils) They are contractile threads, arranged longitudinally in sarcoplasm in each muscle fibers. Striation

Skeletal Muscle

Cardiac Muscle Found in the heart only. Their fibers are characterized by their rhythmic contractions which produce heart beats.

Cardiac Muscle The fibers branched and connected together forming network structure. Striated, their striations fainter than those of skeletal muscle fibers. Numerous nuclei, involuntary. Intercalated disc: dark lines, traversed muscle fibers.