chapter 7

Chapter 7{7}: Bone Tissue and The Skeletal System
Icebreaker: Why Bone Matters

  • Bone = Solid Connective Tissue: Its #1 job is protecting your internal organs.

  • Big Questions to Focus On:

    • Where does bone strength come from?

    • What else does it do besides protect?

    • How does it heal itself after a break?

7.1{7.1} Functions of the Skeletal System

  • The Build: Made of Bone + Cartilage.

  • 66 Critical Functions:

    1. Rigidity: Keeps you from being a blob; provides a framework.

    2. Movement: Acts as a lever for muscles to pull on.

    3. Protection: Think of the skull for the brain or ribs for the heart.

    4. Mineral Storage: A bank for minerals like Calcium (Ca2+Ca^{2+}).

    5. Energy Storage: Yellow Marrow stores fat (adipose tissue).

    6. Blood Production: Red Marrow makes your blood cells.

Quick Look: Cartilage

  • Hyaline Cartilage: The "glider." Found at the ends of bones. If this wears out, you get osteoarthritis.

  • Fibrocartilage: The "shock absorber." Found in your spine and knees.

  • Elastic Cartilage: Not part of the skeletal system (it's in your ears!).

Anatomy of a Typical Bone: The Breakdown

  • Compact Bone: The tough outer shell.

  • Spongy Bone: The porous inside; holds the red marrow.

  • Medullary Cavity: The hollow center; holds the yellow marrow.

  • Periosteum: The "skin" of the bone; full of nerves and blood vessels.

  • Articular Cartilage: Smooth coating at the joints.

  • Ligaments: The "tape" that holds bone to bone.

7.2{7.2} Bone Classification (By Shape)

  1. Long (Levers): Longer than they are wide (e.g., Femur, Humerus).

  2. Short (Stability): Cube-ish (e.g., Carpals in the wrist).

  3. Flat (Shields): Thin/curved (e.g., Sternum, Skull bones).

  4. Irregular (Complex): Unique shapes (e.g., Vertebrae).

  5. Sesamoid (Protective): Small/round, inside tendons (e.g., Patella/Kneecap).

Anatomy of a Long Bone (The Technical Parts)

  • Epiphysis: The ends of the bone.

  • Diaphysis: The long middle shaft.

  • Metaphysis: The "in-between" part where the growth plate (epiphyseal plate) lives.

  • Endosteum: The inner lining of the medullary cavity.

7.3{7.3} Bone Markings: The Map

  • Articulating Surfaces: Where bones touch (Condyle, Facet, Head).

  • Depressions: Dips or basins (Fossa, Sulcus).

  • Projections: Sticky-outy parts for muscles to grab (Crest, Spine, Tuberosity).

  • Holes/Spaces: For blood vessels/nerves to pass through (Foramen, Meatus, Sinus).

Microscopic Structure

  • Bone vs. Cartilage:

    • Cartilage: Avascular (no blood supply), meaning it heals very slowly.

    • Bone: Highly vascular (lots of blood), which is why it heals faster than cartilage.

  • Cells:

    • Chondroblasts/cytes: Build and maintain cartilage.

    • Lacunae: Little pockets where these cells live.