After reading this post you will know:
- What is cartilage (definition)?
- Functions of cartilages.
- Characteristic features of cartilage tissue.
- Components of cartilage.
- Types of cartilage and their sites.
- Differences between hyaline, elastic and fibrous cartilage.
Q. What is cartilage?
A. Cartilage is a specialized connective tissue designed to give support to regions of body that require rigidity and flexibility.
Q. What the functions of cartilages?
A. Functions of Cartilages:
- Form framework for respiratory passage to prevent their collapse.
- Act as shock absorber in spine ( intervertebral discs).
- Resist compressive forces at joints ( articular catilages).
- Helps in growth of bone (epiphyseal plate).
Q. What are the characteristic features of Cartilages.
A. Characteristic features of Cartilages:
- Cartilages lack blood vessels, lymphatics and nerves.
- Cartilages are supplied by diffusion of oxygen and nutrients through extracellular matrix from blood vessels in perichondrium /surrounding tissues/synovial fluid.
- Extracellular matrix of cartilages is highly permeable.
- Cartilages have poor regeneration capacity.
- Cartilages are usually surrounded by perichondrium (except articular cartilage and fibrocartilage).
Q.What are the components of cartilages?
A. Components of cartilages:
- Cells are chondroblasts and chondrocytes
- Fibres are collagen and elastic ( impart tensile strength and elasticity)
- Ground substance is made up of hyaluronic acid , glycosaminoglycans and (chondroitin sulphate, keratan sulphate), glycoproteins (chondronectin).
Q. What is perichondrium?
A. Perichonrium is a connective tissue sheath that surrounds the hyaline and elastic cartilages.
- It has two layers:
- outer fibrous layer contains collagen fibers, fibroblasts, blood vessels.
- Inner chondrogenic layer is cellular. It contains chondrogenic cells and chondroblasts.
- It helps in growth and repair of cartilage.
Q. What are the characteristic features of Chondroblasts and chondrocytes?
A. Chondrocytes and chondroblasts are derived from mesenchymal cells.
- oval shaped young cells with cell processes.
- present in perichondrium.
- precursors of chondrocytes.
- older and mature cells.
- oval shaped and small at the periphery.
- round and large towards the center.
- located within the lacunae, singly or in isogenous groups.
Q. Differentiate between hyaline, elastic and fibrous cartilage.
Q. How does a cartilage grows?
A. Cartilage grows by two methods:
Interstitial growth: In this type of growth the cartilage grows by mitotic divisions of existing chondrocytes and deposition of the extracellular matrix by these newly formed chondrocytes.
Appositional growth: In this type of growth, the inner layer of perichondrium cells ( chondrogenic cells) divide and differentiate into chondroblasts. The newly formed cells and matrix are added at the periphery/surface .