SKELETAL

• Skeletal system

  206 bones in the human body
• Skeletal system


  206 bones in the human body
• Skeletal system


  206 bones in the human body
• Skeletal system


  206 bones in the human body
• 206 bones in the human body
• Categories of bones


  • Long bones
  • Short bones
  • Flat bones
  • Irregular bones
• Long bones


  • Shaped like rods or shafts with rounded ends
  • Diaphysis is primarily cortical bone
  • Epiphysis are primarily cancellous bone
  • Epiphyseal center for longitudinal growth (once it closes there is no chance tumangkad)
  • Designed for weight bearing and movement
• Osteoblasts


  Cells responsible for bone formation by secreting bone matrix (collagen and ground substances) that provide a framework
• Ground substance


  Produced by glycoproteins as well as proteoglycans, provides the matrix including collagen that provides the framework of bone
• Osteocytes


  Mature bone cells involved in bone maintenance, located in lacunae
• Osteoclasts


  Multinuclear cells involved in dissolving and resorbing bone, located in shallow howship's lacunae
• Ossification


  Bone matrix is formed and hard mineral crystals composed of calcium and phosphorus are bound to the collagen fibers
• Bone


  • Mineral content provides strength
  • Collagen content provides resilience
• Bone maintenance


  1. Modeling: bones grow and form

  2. Remodeling: maintains bone structure and function through simultaneous resorption and osteogenesis
• Factors influencing balance between bone resorption and formation

  • Physical activity
  • Dietary intake of certain nutrients (1000-1200 mg of calcium daily/ 16 to 24 ounces of milk daily)
  • Hormones: calcitriol, PTH, calcitonin, thyroid hormone, cortisol, growth hormone, estrogen, and testosterone
• PTH


  Responsible for calcium concentration in the blood, increases resorption in hypocalcemia
• Calcitonin


  Produced by thyroid gland, released in response to hypercalcemia to inhibit bone resorption
• Estrogen


  Stimulates osteoblast (bone formation) and inhibits osteoclast, decreases bone resorption
• Testosterone


  Promotes bone and growth formation
• Menopause


  Normal decrease of estrogen, increased risk of osteoporosis
• Phases of bone healing

  1. Reactive phase

  2. Reparative phase

  3. Remodeling phase
• Synarthrosis joints


  Immovable (skull sutures)
• Amphiarthrosis joints


  Allow limited motion, bones joined by fibrous cartilage (vertebral joints and the symphysis pubis)
• Types of diarthrosis (freely movable) joints

  • Ball-and-socket joints
  • Hinge joints
  • Saddle joints
  • Pivot joints
  • Gliding joints
• Joint capsule


  • Tough, fibrous sheath surrounding the articulating bones
• Synovium


  Capsule is lined with a membrane, secretes the lubricating and shock-absorbing synovial fluid
• Ligaments


  Fibrous connective tissue bands, bind the articulating bones together
• Bursa


  Sac filled with synovial fluid that cushions the movement of tendons, ligaments, and bone
• Isometric contraction


  Length of the muscle remains constant but the force generated is increased
• Isotonic contraction


  Shortening of muscle with no increase in tension within the muscle
• Muscle


  • Muscles containing large quantities of myoglobulin contract slowly and powerfully
  • Muscles containing little myoglobulin contract quickly
• Muscle tone


  • Flaccid
  • Spastic
  • Atonic
• Muscle action


  Muscles accomplish movement by contraction
• Muscle roles


  • Prime mover
  • Synergists
  • Antagonists
• Muscles need to be exercised to maintain function and strength
• Hypertrophy


  Increase in the size of individual muscle fiber without an increase in their number
• Hyperplasia


  Increase in the number of muscle cells
• Atrophy


  Decrease in the size of a muscle
• Muscle containing little myoglobulin


  • Contract quickly (extraocular muscles)
• Muscle tone


  State of readiness to respond to contraction stimuli