انسجة

• 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)