muscular system

• Functions of the human muscles

  • Movement
  • Maintain posture
  • Blood circulation
• Skeletal muscles

  64o skeletal muscles + all smooth muscles
• Muscle composition

  • Each muscle is made of muscle fibers and muscle tissue, includes surrounding connective tissue, blood vessels, and nerves
• Types of muscles

  • Cardiac muscle (heart)
  • Skeletal (striated) muscle
  • Smooth muscle
• Skeletal muscle

  Cells are highly modified for contraction
• Tendon


  Binds muscle to bone
• Ligament


  Binds bone to bone
• Skeletal muscle movement

  1. Nervous system stimulates skeletal muscles to contract

  2. Muscles can only pull bones, they cannot push

  3. Muscle contraction requires ATP energy

  4. Skeletal muscles work in opposition (antagonistic pairs)
• Skeletal muscle structure

  • Myofibrils are rod-like organelles of muscle cells that consist of different proteins and aid in contraction
  • A bundle of myofibrils make a muscle fiber, a bundle of muscle fibers make muscles
  • Muscle fibers are multinucleated (nuclei lie beneath the membrane), fibers contain mitochondria
  • Myogenesis: the formation of skeletal muscle that involved the fusion of cells
  • Sacromeres: contractile units contained in myofibrils, dominated by the proteins actin and myosin
• Muscle contraction

  1. Each sacromere gets shorter

  2. Because sacromeres are connected, the entire muscle contracts

  3. Muscle pulls on a tendon connected to a bone, and movement of the skeleton occurs
• Muscular system diseases

  • Tendinitis
  • Muscle strains
• Tendinitis


  Inflammation of the tendons, causes/risks: overuse, bad posture, infection, common around shoulders, elbows, wrists, knees, heels, genetics, sex (males), treatment: healed by exercise and mobility aids
• Muscle strains


  Tearing of the muscle fibers, causes: injuries, poor flexibility, overexertion, treatment: rest, medicine