MUSCLE TISSUE

• Contractility is an inherent property of all cells, which is the ability to shorten.
• Pericytes, myoepithelial cells, and muscle cells exhibit contractility.
• Pericytes are cells that wrap around endothelial cells around the walls of small blood vessels.
• Myoepithelial cells embrace the acini and small ducts of some exocrine glands.
• Muscle cells exhibit the greatest degree of contractility among all cells in the body.
• Muscle cells comprise the cellular elements of muscle tissue.
• Muscle tissue is responsible for the locomotion of the individual and the movement of various parts of the body.
• Muscle tissue is composed of muscle cells that are supported and bound together by intercellular material.
• Muscle cells are derived from mesoderm.
• Iris of the eye arises from ectoderm.
• Iris of the eye is often referred to as muscle fibers.
• Sarcolemma is the cell membrane of muscle fibers.
• Sarcoplasm is the cytoplasm of muscle fibers.
• Sarcoplasmic reticulum is the endoplasmic reticulum of muscle fibers.
• Sarcosomes is the mitochondria of muscle fibers.
• Striated muscles exhibit prominent alternating light and dark cross striations.
• Non-striated muscles do not exhibit cross striations.
• Skeletal and cardiac muscle fibers are striated.
• Smooth muscle cells are non-striated.
• Skeletal muscle tissue forms mouse-shaped organs, which are muscles or skeletal muscles.
• A muscle is attached at either end of the tendon (dense regular connective tissue) and a part of the skeletal system (bone or cartilage).
• Origin is when the attachment occurs on a bone that remains immobile during an action.
• Insertion is when the attachment is on a bone that moves during the action.
• The upper third of the esophagus and the muscles of facial expression are the skeletal muscles whose ends are not attached to the skeletal system.
• Skeletal muscle is also known as voluntary muscle.
• Voluntary muscle comprises the muscles of the limbs, body wall, and face.
• The biceps branchii is a collection of numerous skeletal muscle fibers bunched in bundles or fascicles.
• A muscle fascicle is a bunch of skeletal muscle fibers surrounded by perimysium.
• Epimysium keeps the fascicles together.
• Perimysium keeps the muscle fibers within the fascicle together.
• Blood vessels and nerve fibers supply the muscle fibers in the fascicle.
• Endomysium is a delicate connective tissue where the extracellular fibers are mainly reticular fibers.
• Skeletal muscle cells are long, tapering, cylindrical, and multinucleated cells. They arise in the embryo from the fusion of myoblasts.
• Myoblasts are mononuclear muscle cell precursors.
• Myosatellite cells serve as stem cells in case of muscle injury.
• Skeletal muscle cells have oval nuclei.
• The sarcoplasm of skeletal muscle cells is acidophilic.
• Lipid droplets and glycogen granules are the inclusions of sarcoplasm.
• Myoglobin is an oxygen-binding protein responsible for the brownish color of muscle.
• Myofibrils are long but thin filamentous elements found in the sarcoplasm.