36.1 ¢â‚¬â€œ The Skeletal System form the skeletal system....

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Transcript of 36.1 ¢â‚¬â€œ The Skeletal System form the skeletal system....

  • Regents Biology

    36.1 – The Skeletal System

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    The Skeleton   All organisms need structural support.

      cytoskeleton (unicellular)   exoskeleton (arthropods) or an endoskeleton


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    The Skeleton   Functions of the skeleton:

      support   protects internal organs   movement   stores mineral reserves   provides site for blood cell


      Bones and other connective tissues (cartilage and ligaments) form the skeletal system.

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    Appendicular Skeleton •  The bones of the arms

    and legs, along with the bones of the pelvis and shoulder area form the appendicular skeleton (grey).

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    Structure of Bones

    Bone marrow


    Spongy bone

    Compact bone

    Haversian canal Compact bone

    Spongy bone


    Osteocyte Artery


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    Structure of Bones   a network of living

    cells and protein fibers surrounded by deposits of calcium salts

      surrounded by a tough layer of connective tissue called the periosteum

      Blood vessels in the periosteum carry oxygen and nutrients to the bone.

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      Osteocytes (mature bone cells) are embedded in the bone matrix.

      Other bone cells (osteoclasts and osteoblasts) line the Haversian canals and the surfaces of compact and spongy bone.   Osteoclasts break down bone.   Osteoblasts produce bone.

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    Bone Marrow   a soft tissue inside

    the cavities within bones

      two types:   Yellow marrow –

    made up of fat cells.

      Red marrow produces red blood cells, some kinds of white blood cells, and platelets.

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    Bone Marrow

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    Development of Bones

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    Development of Bones   The skeleton of an embryo is composed of cartilage

    (strong connective tissue, softer and more flexible than bone).

      Cartilage is replaced by bone ossification.   Bone tissue forms as osteoblasts secrete mineral

    deposits.   When the osteoblasts become surrounded by bone

    tissue, they mature into osteocytes.

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      Many long bones have growth plates at either end.

      Growth of cartilage at these plates causes bones to lengthen. Gradually, this cartilage is replaced by bone tissue.

      By early adulthood, cartilage in the growth plates is replaced by bone, the bones become ossified, and growth stops.

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    Bone Growth

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    Joints   where one bone attaches to

    another bone is called a joint

      Joints permit bones to move without damaging each other.

      3 types: immovable, slightly movable, or freely movable

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    Immovable Joints   “fixed joints”

    allow no movement

      bones are interlocked and held together by connective tissue, or they are fused together

      Ex: skull bones

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    Slightly Movable Joints

      permit a small amount of restricted movement

      Ex: joints between adjacent vertebrae

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    Freely Movable Joints   permit movement in one

    or more directions

      4 common types

     ball-and-socket joints (many directions)

     hinge joints (back- and-forth)

     pivot joints (one bone rotates around the other)

      saddle joints

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    Structure of Joints   Ligaments hold bones

    together in joints and are attached to membranes that surround bones.

      Synovial fluid lubricates surface of joint, enabling the bones to slide past each other more smoothly.

      Bursae act as shock absorbers.