Skeletal System: Overview and Cartilage

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Skeletal System: Overview and Cartilage
2015-10-10 17:23:30
Test Two
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  1. Composition of the skeletal system
    notochord, cartilage, bone
  2. Functions of the skeletal system
    form, locomotion, supports and protects viscera, and stores Ca++ salts
  3. Notochord
    - length
    extends from the tail up to the base of the skull just beneath the brain; does not extend forward
  4. Notochord
    - purpose in amphioxus and primitive
    In amphioxus and primitive: it acts as the axial support of the body and it is extremely flexible in them so that when the fish start swimmng, it straightens out--gives undulating movement
  5. Notochord
    - purpose in advanced fishes and tetrapods
    the vertebrae encroaches on the notochord; the vertebrae replace the notochord in its function as the chief axial support
  6. Notochord
    - contains?
    no blood vessels  or nerves
  7. Notochord
    - structure
    • a dorsal rod that is avascular and is not innervated (no nerves) made up of tghtly packed cells with little or no intercellular space between the cells
    • - the cells contain large vacuoles that are fluid-filled, which keep the cells turgent; and, with this, we have a stiffened rod 
    • On the outside are two coverings or sheaths
  8. Explain the sheaths of the notochord.
    OUter: elastic connective tissue to give some flexibility

    Inner: thicker layer of dense fibrous CT

    These sheaths are acellular; they are basically fibers; they play an important role in organisms that form vertebral columsns
  9. Notochords are only present as __
    continuing structure in life of the primitive fish; in other organisms, it is squeezed out by vertebrae or just barely exists in centrum of vertebrae
  10. Cartilage
    - General considerations
    third to mammals the hardest tissue; provides form, structure, and support; found in both vertebrates and invertebrates; in condrichthians, it forms most or all of the skeleton; loss of bone in condrichthians may be adaptive thing; in all other vertebrates, it’s present to some extent alongside bone
  11. Cartilage
    - Histology
    avascular; gets its nutrient supply from a connective tissue covering that surrounds all cartilage called the perichondrium [chondrium=cartilage]; dense, fibrous, irregular tissue is the perichondrium
  12. Cartilage
    - cell types
    • chondroblasts (immature cartilage cell that is responsible for secreting the matrix of cartilage)
    • chondrocytes
  13. Cartilage
    - matrix
    • amorphous
    • embedded in it is the fibers and mucopolysaccharides
    • they get stuck in the matrix and become chondrocytes—not active in the matrix
    • mature
    • if you pull out the cell, the space that the chondrocyte resides in is called the lacuna
  14. Types of cartilage
    • hyaline
    • fibrous
    • elastic
    • calcified
  15. hyalin cartilage
    • -most prevalent cartilage in all vertebrates
    • - the fibers in here are collagenous
    • - pretty strong cartilage
    • - it is the cartilage of many of the vertebrate skeletal structures before they are bone
    • - there are preformed cartilage models in the embryo of many structures
    • - does not turn into bone
    • - used as a template for bone to form
  16. Fibrous cartilage
    • combination of dense fibrous CT and hyaline cartilage
    • chondrocytes line up between the dense bundles of fibers
    • very strong cartilage
  17. Elastic cartilage
    • poteins are elastic and highly flexible
    • provide more stability
    • less support
    • the pinna of your ear is this
  18. calcified cartilage
    • hyaline cartilage where there are bits of hydroxyapatite embedded in it
    • composed of calcium salts
    • the whole matrix is not embedded with it, but there are small bits of it
    • strongest of all cartilage