How bones are formed?

Описание: Bones are formed through a process called ossification (or osteogenesis). It starts before birth and continues as you grow. There are two main types of bone formation:
🦴 1. Intramembranous Ossification
• Where: Flat bones like the skull, face, and clavicle.
• How:
1. Mesenchymal cells (stem cells) in connective tissue cluster together.
2. They change into osteoblasts (bone-forming cells).
3. Osteoblasts secrete bone matrix (made of collagen and minerals).
4. The matrix hardens → forms spongy bone, then compact bone develops around it.
🦴 2. Endochondral Ossification
• Where: Most bones of the body (long bones like femur, humerus).
• How:
1. A cartilage model of the bone forms first.
2. Blood vessels enter → bring osteoblasts.
3. Cartilage is gradually replaced by bone tissue.
4. Bone grows in length at the growth plate (epiphyseal plate) until adulthood.
🔬 Main Cells Involved:
• Osteoblasts – form new bone
• Osteocytes – mature bone cells that maintain bone tissue
• Osteoclasts – break down old or damaged bone
⚙️ Key Materials:
• Collagen fibers – provide flexibility
• Calcium and phosphate – give hardness and strength