انسجة

Cards (8)

  • Muscular tissue
    Composed of a soft of specialized cells containing contractile proteins that generate forces necessary for cellular contraction, driving movement within organs and the body
  • Muscle cells
    • Contain contractile proteins like actin and myosin that slide past one another, producing contraction that changes length and shape of cell
    • Made up of cells called myocytes
    • Elongated structure in one direction (muscle fibers)
  • Functions of Muscular Tissue
    • Movement: muscle contraction leads to different types of body and organ movements
    • Maintain posture of the body
    • Heat generation: contraction produces heat to maintain body temperature
    • Stabilization of joints
    • Moving substances within the body (e.g. heart pumping blood, digestive tract)
  • Types of Muscle Tissues
    • Skeletal muscle
    • Cardiac muscle
    • Smooth muscle
  • Skeletal muscle
    • Found covering the skeleton and attached to bones, generates locomotion and body movement
    • Muscle fibers are very long, cylindrical, striated, multinucleated
    • Fibers are arranged parallel to each other
    • Contain myofibrils with contractile elements (striations, sarcomeres, myofilaments)
  • Smooth muscle
    • Non-striated, forms walls of various hollow organs and tubes
    • Cells are spindle-shaped with single central nuclei
    • Contains thick, thin, and intermediate filaments
    • Contraction changes size and shape of organs
  • Cardiac muscle
    • Occurs only in the heart, forms the myocardium
    • Resembles both skeletal and smooth muscle, but is unique in its structural details and automatic, spontaneous contractions
    • Cells are short, branched, striated, with intercalated discs
    • Supplied by autonomic nervous system
    • Cells are connected by gap junctions, acting as a single functional unit (syncytium)
    • High mitochondrial content for continuous aerobic metabolism
    • Contractions controlled by pacemaker cells
  • Heart wall layers
    • Endocardium (inner lining)
    • Myocardium (middle cardiac muscle layer)
    • Epicardium (outer layer, also called pericardium)