#AnatomyOfBones

#Biology

#Science

Anatomy of Bones

• Bone is living tissue that makes up the body's skeleton. There are 3 types of bone tissue:

  
  

          - Compact tissue - This is the harder, outer tissue of bones.

  
  

          - Cancellous tissue - This is the sponge-like tissue inside bones.

  
  

          - Subchondral tissue - This is the smooth tissue at the ends of bones.

  
  

• The Diagram :

• The tough, thin outer membrane covering the bones is called the periosteum. Under the hard outer shell of the periosteum are tunnels and canals. Through these, blood and lymphatic vessels carry nourishment for the bone. Muscles, ligaments, and tendons may attach to the periosteum.

Compact Tissues

• Compact bone tissue is hard because of the minerals and organic materials in its extracellular matrix.

• Osteoid is a protein mixture that osteoblasts secrete to form the organic matrix of bone. It's a gelatinous substance made up of collagen, a fibrous protein, and mucopolysaccharide, an organic glue. Osteoid makes up about half of bone volume and 40% of bone weight.

• Bones are made of calcium because calcium is essential for nervous systems to function and the ocean had loads of it. But fresh water doesn't.

• Calcium makes up about 40% of the mass of bone mineral and slightly less than 20% of the dry weight of bone in the adult human body.

Cancellous Tissue

• House Bone Marrow: Cancellous bone, also known as spongy bone, functions to house bone marrow, which is responsible for producing red blood cells through a process called erythropoiesis. This allows the bone to serve as a site for blood cell formation.

  
  

• Light and Less Dense: Another function of cancellous bone is to contribute to the overall structural characteristics of bones by making them less dense and more lightweight than cortical or compact bone. This helps in reducing the overall weight of bones while maintaining strength and flexibility.

  
  

• Source of Osteoprogenitor Stem Cells: Cancellous bone acts as an incubator for pluripotent osteoprogenitor stem cells, ensuring the maintenance and renewal of these crucial cellular sources within the bone. These stem cells play a significant role in bone repair and regeneration.

Subchondral Tissue

• Subchondral tissue is the smooth tissue found at the ends of bones, which is covered with cartilage, a specialized rubbery connective tissue.

• It provides structural support and helps reduce friction between bones, facilitating smooth joint movement.

• Cartilage is composed of a dense extracellular matrix (ECM) containing chondrocytes, which are specialized cells responsible for producing and maintaining the cartilaginous matrix. The matrix primarily consists of water, collagen, and proteoglycans, along with other proteins and glycoproteins in smaller quantities.