SKELETAL SYSTEM 1

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  4 COMPONENTS OF THE SKELETAL SYSTEM

  1. bones
  2. cartilage
  3. tendons
  4. ligaments
• Functions of the skeletal system

  1. body support
  2. organ protection
  3. body movement
  4. mineral storage
• Cartilage In mature form, the suffix -cyte replaces -blast in the name.


  cartilage
• Contraction of the skeletal muscles moves the bones, producing body movements.
• Joints, which are formed where two or more bones come together, allow movement between bones.
• Skeletal muscles attach to bones by tendons, which are strong bands of connective tissue.
• Smooth cartilage covers the ends of bones within some joints, allowing the bones to move freely.
• Ligaments allow some movement between bones but prevent excessive movements.
• If the blood level of minerals decreases, the minerals are released to the blood.
• Principal minerals: Calcium and Phosphorus. (essential minerals for many psychological processes.
• Adipose tissue is also stored within bone cavities.
• the lipids are released into the blood and used by other tissues as a source of energy.
• 3 types if cartilages

  1. hyaline cartilage
  2. fibrocartilage
  3. elastic cartilage
• The most intimately associated with bone. Its structure is important because most bones in the body start out as a hyaline cartilage model.
• growth in bone length and bone repair often involve making hyaline cartilage first, then replacing it with bone
• cartilages

  Immature cell names often end with the suffix -blast, which means “seed” or “bud.”
• cartilage In mature form, the suffix -cyte replaces -blast in the name.


  cartilage
• Hyaline cartilage chondroblasts produce a matrix surrounding themselves . By the time the matrix has surrounded a chondroblast, the cell has differentiated into a chondrocyte.
• a rounded cell that occupies a space within the matrix


  lacuna
• for bearing weight and is the major supporting tissue of the body.

  rigid, strong bone
• provides a firm yet flexible support within certain structures, such as the nose, external ear, thoracic cage, and trachea.

  cartilage
• are strong bands of fibrous connective tissue that hold bones together.

  ligaments
• the skull encloses and protects the brain, and the vertebrae surround the spinal cord.
• The rib cage protects the heart, lungs, and other organs of the thorax
• The matrix contains collagen, which provides strength, and proteoglycans, which make cartilage resilient by trapping water.
• most cartilage is covered by this protective connective tissue sheath


  perichondrium
• perichondrium: double-layered outer layer of dense irregular connective tissue containing fibroblasts.
• Perichondrium: The inner, more delicate layer has fewer fibers and contains chondroblasts.
• Blood vessels and nerves penetrate the outer layer of the perichondrium but do not enter the cartilage matrix, so nutrients must diffuse through the cartilage matrix to reach the chondrocytes
• hyaline cartilage that covers the ends of bones where they come together to form joints, has no perichondrium, blood vessels, or nerves


  Articular cartilage
• 2 types of cartilage growth

  1. appositional growth
  2. interstitial growth
• chondroblasts in the perichondrium add new cartilage to the outside edge of the existing cartilage. The chondroblasts lay down new matrices and add new chondrocytes to the outside of the tissue.

  appositional growth
• chondrocytes in the center of the tissue divide and add more matrix in-between the existing cells

  interstitial growth
• new cartilage is added to the surface of the cartilage by chondroblasts from the inner layer of the perichondrium

  appositional growth
• new cartilage is formed within the cartilage by chondrocytes that divide and produce additional matrix

  interstitial growth
• characterized by having spread-out cells separated by a non living material called matrix.

  connective tissue
• In bone, as in other connective tissues, the bone cells produce the bone matrix and become entrapped within it.
• By weight, mature bone matrix is normally about 35% organic and 65% inorganic material
• Bone matrix: Organic material consists primarily of collagen and proteoglycans.
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  Bone matrix: Inorganic material consists primarily of a calcium phosphate crystal called hydroxyapatite