Cartilage is a tough semi-transparent flexible tissue that consists of a tough matrix or jelly-like substance. The matrix is made up of collagen (a protein) and proteins with special carbohydrate chains called proteoglycans. Cartilage is enclosed by a fibrous capsule called the perichondrium. It consists of living cells called chondrocytes which secrete a rubbery protein matrix called chondrin. Chondrocytes occur in small fluid-filled spaces called lacunae which are scattered throughout the matrix. There are no blood vessels or nerves in the matrix.
Cartilage and bone
Infant and young children do not have bones like those of adults. Their bones are made mostly of cartilage – a firm, elastic, fibrous material. As the individual grows and matures, the cartilage is gradually replaced by bone cells which deposit crystals of calcium carbonate and calcium phosphate. This process called ossification greatly increases the strength of the bone.
|Hyaline cartilage||glass-like, bluish-white, few fibres||at ends of bones, forms c-shaped structures in Trachea, joins ribs to sternum, larynx and tip of nose, temporary cartilage in bones||reduces friction at joints, allows movement of ribs during breathing, forms permanent structures, allows bones to increase in length|
|Fibrocartilage||many white collagen fibres||discs between the vertebrae, in the rim of ball and socket joints, between pubic bones||acts as shock absorbers, makes the socket deeper while still allowing movement|
|Elastic||many yellow fibres in matrix||in the pinna of the ear, in the epiglottis||maintains the shape of the ear, strengthens the epiglottis|