MUSCULAR SYSTEM

• Functions of muscular system

  1.      Movement of the body

  2.      Maintenance of posture

  3.      Respiration

  4.      Production of body heat.

  5.      Communication

  6.      Constriction of organs and vessel

  7.      Contraction of the heart
• Skeletal muscle has four major functional characteristics:

  contractility, excitability, extensibility, and elasticity
• Membrane of muscle fiber.

  sarcolemma
• tubelike invagination


  transverse tubules
• complex network of specialized smooth endoplasmic reticulum

  sarcoplasmic reticulum
• The cytoplasm of a muscle fiber.

  sarcoplasm
• sarco means


  flesh
• Myofibrils consist of two major kinds of proteins fibers

  1.      Actin myofilaments

  2.      Myosin myofilaments
• smallest portion of a skeletal muscle capable of contracting.

  sarcomeres
• i band


  the light staining bands, only actin myofilaments
• sliding of actin myofilaments past myosin myofilaments during contraction

  Sliding Filament Model
• is the contraction of a muscle fiber in response to a stimulus

  Muscle Twitch
• the force of contraction of individual muscle fibers is increased by rapidly stimulating them.

  summation
•  

  is a sustained contraction that occurs when the frequency of stimulation is so rapid, and no relaxation occurs.

  Tetanus
• • more motor units are stimulated, which increases the total number of muscle fibers contracting.

  Recruitment
• Muscle Fibers are sometimes classified as either slow - twitch or fast twitch.

  fiber types
• which occurs in mitochondria, requires O2 and break down glucose to produce ATP, CO2 and H2O.

  Aerobic respiration
• which does not require O2, and break down glucose to produce ATP and lactate.

  anaerobic respiration
• -increase the tension in the muscle without changing its length.

  Isometric contraction (equal distance)
• -have constant amount of tension while decreasing the length of the muscle.

  Isotonic contraction (equal tension)
• The muscle shortens as it contracts.

  Concentric contraction
• The muscle lengthens as it contracts.

  Eccentric contraction
• constant tension produced by body muscles over long period of time.

  Muscle Tone