Cartilage is a type of connective tissue that provides support and shape to the body. It is found in various parts of the body, including the ears, nose, and joints.

Anatomy of Cartilage

  1. Chondrocytes: These are the only cells found in cartilage and are responsible for maintaining and producing the extracellular matrix.
  2. Extracellular Matrix (ECM): The ECM is composed of water, collagen fibers, and proteoglycans. Proteoglycans are large molecules that are composed of a core protein and glycosaminoglycan (GAG) chains, which give the cartilage its ability to resist compressive forces.
  3. Perichondrium: Cartilage is surrounded by a layer of connective tissue called the perichondrium, which contains blood vessels and nerves that supply the cartilage with nutrients and oxygen.

Types of Cartilage

There are three types of cartilage found in the human body:

  1. Hyaline Cartilage: Hyaline cartilage is the most common type of cartilage. It is found in joints, the rib cage, and the trachea. This type of cartilage is smooth and has a bluish-white appearance. Hyaline cartilage provides a smooth surface for the bones to glide over in the joints.
  2. Elastic Cartilage: Elastic cartilage is found in the external ear, the epiglottis, and the larynx. This type of cartilage contains more elastic fibers than hyaline cartilage, which makes it more flexible.
  3. Fibrocartilage: Fibrocartilage is found in the intervertebral discs, the pubic symphysis, and the menisci of the knee joint. This type of cartilage contains more collagen fibers than hyaline cartilage, which makes it stronger.

Physiology of Cartilage

  1. Maintenance of Extracellular Matrix: Chondrocytes are responsible for the production and maintenance of the ECM, which gives cartilage its unique properties such as its ability to resist compressive forces.
  2. Avascularity: Cartilage is avascular, meaning it lacks blood vessels. Therefore, nutrients and oxygen must diffuse from the perichondrium to the chondrocytes.
  3. Limited Regeneration: Cartilage has a limited ability to regenerate, as chondrocytes have a low mitotic rate and limited ability to migrate. Injuries to cartilage often result in scar tissue formation rather than true regeneration.
  4. Joint Lubrication: Articular cartilage in joints helps to reduce friction and provide lubrication during joint movement. The ECM of articular cartilage is highly specialized to provide this function.
  5. Growth and Development: During growth and development, cartilage serves as a template for bone formation. As bones grow, the cartilage is gradually replaced by bone tissue.

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