lecture 11

Class Policies and Expectations

• Attendance is crucial; missing class makes it hard to catch up on material.

• Students are treated as adults; no need to ask for bathroom breaks.

• Open communication is encouraged; students can ask questions privately or openly.

Introduction to the Skeletal System

• Transition from discussing diseases to the skeletal system.

• Functions of the Skeletal System:

  • Support the body.

  • Protect internal organs.

  • Allow movement.

  • Produce blood cells.

  • Serve as a reservoir for calcium and phosphorus.

Importance of Calcium

• Essential for bone development and overall body functions (e.g., blood clotting, muscle contractions).

• Bone is categorized into two groups: Axial Skeleton and Appendicular Skeleton.

Axial Skeleton

• Composed of:

  • Skull

  • Vertebrae (spine)

  • Ribs (attached to sternum)

Appendicular Skeleton

• Composed of:

  • Arms and legs

  • Pelvis (pelvic girdle)

  • Shoulders (pectoral girdle)

Terms Related to Bone Formation

• Bone begins as cartilage in the fetus, gradually replaced by bone cells (osteoblasts).

• Osteoblasts: Precursor cells that secrete matrix to form bone.

  • The matrix in cartilage is called chondrin; in bone, it is osteon.

• Osteocytes: Mature bone cells that maintain bone structure.

• Osteoclasts: Cells that break down and reabsorb bone, important for creating channels for blood supply

Growth and Composition of Bone

• Young children have a higher ratio of bone to protein (2:1), allowing flexibility.

• In adults, the ratio is 1:1, while in the elderly, it drops to 1:2, leading to brittleness.

Important Terminology

• Hydroxyapatite: A key component in the conversion of cartilage to bone.

• Bone Categories:

  • Long Bones: Arms, legs, fingers, toes.

  • Short Bones: Bones in wrists and ankles.

  • Irregular Bones: Vertebrae and facial bones.

  • Flat Bones: Bones of the cranium and scapula.

  • Sesamoid Bones: Embedded in tendons (e.g., kneecap).

Basic Bone Structure

• Key components include:

  • Epiphysis: Ends of the bone.

  • Diaphysis: Shaft of the bone.

  • Periosteum: Membrane covering the shaft.

  • Medullary Cavity: Hollow part containing bone marrow.

• Epiphyseal Plate: Location where bone growth occurs; important for height increase during childhood and adolescence.

Impacts of Injury on Bone Growth

• Injuries affecting the epiphyseal plate can lead to unequal growth of limbs.

• Importance of protecting children from injuries to the growth plate to prevent future complications.

Conclusion**

• The skeleton offers crucial structural support,

• It serves multiple functions from protection to movement.

• Understanding the anatomy and physiology of bones is essential for maintaining overall health.