bones

Supporting Systems

Importance of Cartilage

• Cartilage is crucial for:

  • Lining many joints facilitating smooth movement.

  • Acting as a shock absorber between vertebrae.

  • Forming flexible structures such as the epiglottis and pinna of the ear.

Spongy Bone (Cancellous Bone)

• Characteristics:

  • Lighter in weight compared to compact bone.

  • Composed of small, thin plates of bone called trabeculae that form an irregular network.

  • Arranged along lines of stress to resist impact.

Functions of Bone

• Bone makes up the bulk of the skeleton and is the hardest tissue in the body.

  • Needs to be light for easier movement.

  • Major functions:

    • Formation of red (erythrocytes) and white (leucocytes) blood cells in the red marrow found in trabecular spaces.

    • Support and strength to the body through compact bone.

• Bone tissue contains:

  • Blood vessels, nerves, and lymph vessels.

  • Osteocytes (inactive mature bone cells), osteoblasts (form new bone), and osteoclasts (break down bone).

Composition of Bone Tissue

• Bone tissue is composed of:

  • Osteocytes located in lacunae.

  • Matrix made up of:

    • Collagen fibers (give bone flexibility).

    • Minerals (calcium salts) that strengthen the matrix.

Classification of Bone Tissue

• Two types of bone tissue:

  1. Compact Bone

     • Found on surfaces and shafts of limb bones, characterized as hard and dense.

     • Integrated with numerous Haversian systems (osteons).

  2. Spongy Bone

     • Contains red marrow, composed of trabeculae arranged for stress resilience.

• Types of bones:

  • Long, short, irregular, and flat bones.

Long Bones Structure

• Long bones are:

  • Holed through the shaft (diaphysis) with two heads (epiphyses).

• Provide support for limbs and attachment for muscles.

  • Example: femur in humans.

Short Bones

• Cube-shaped bones, nearly equal in length and width.

  • Like wrist (carpals) and ankle (tarsals) bones, facilitate movement.

Flat Bones

• Thin, flattened, and slightly curved structure.

  • Comprise two layers of compact bone surrounding a layer of spongy bone.

  • Protect vital organs and provide attachment area for muscles.

  • Example: cranial bones, sternum, ribs, scapulae.

Irregular Bones

• Bones that don't fit into other classifications due to complex shapes.

  • Mainly made up of spongy bone with surrounding compact bone.

  • Examples include vertebrae and hip bones.

Verification and Demonstration Activities

Demonstration 1: Effect of Heat on Bone

• Process:

  • Hold bone fragment in Bunsen burner flame.

• Results to Observe:

  • Observe texture and appearance changes after crushing cooled bone.

Bone Fractures

• Definition:

  • Fractures are breaks or cracks in bones due to trauma or stress.

  • Types:

    • Stress fracture: small crack from pressure.

    • Greenstick fracture: incomplete break, common in children.

• Causes:

  • Trauma from fall, vehicle accidents, and diseases weakening bones, e.g., osteoporosis.

Descriptions of Fractures

• Types of fractures:

  • Complete: bone breaks into two pieces.

  • Incomplete (Greenstick): bone cracks without breaking completely.

  • Simple: clean break without skin penetration.

  • Compound (Open): breaks penetrate the skin.

  • Comminuted: bone fragments into many pieces.

Functions of the Human Skeleton

1. Support: Keeps the body upright and maintains shape.

2. Protection: Shields internal organs (heart, lungs, brain).

3. Movement: Acts as levers for muscles.

4. Blood Cell Production: Red marrow produces blood cells.

5. Mineral Storage: Stores calcium and phosphates.

6. Hearing: Ossicles transmit sound waves in the ear.

Structure of the Vertebral Column

• Function:

  • Supports the head, encloses/protects the spinal cord.

  • Attaches to ribs and serves as muscle attachment point.

  • Allows spinal nerves to pass through openings.

  • Absorbs shocks and aids in balance, possessing four curves.

Vertebrae

• Composed of 33 small bones, forming strong, flexible chain.

• Joints between vertebrae:

  • Allow limited movement; shock-absorbing discs promote flexibility.

  • Curvatures assist with balance and shock absorption.