Structure and Functions of Cartilage Tissue
Note: This page is part of the section
about the structure and function of different Tissue
Types, which is related to the section about Histology
and Cells (incl. structure
of animal cells, cell
division, mitosis, meiosis).
This "Tissue Types" section is included to complete description
of the knowledge of "Histology - The Cell" required by
some courses in First-Level Anatomy and Physiology. To read about
other tissue types see the list of on the left.
In the fetus and infant cartilage occurs in many
parts of the body but much of this juvenile cartilage disappears
during growth
and development. The information on this page is concerned
primarily with cartilage tissue in adult humans.
The Structure (Physical Description)
of cartilage tissue in general
Cartilage is a connective tissue consisting of a dense
matrix of collagen fibres and elastic fibres embedded in a rubbery
ground substance. The matrix is produced by cells called chondroblasts,
which become embedded in the matrix as chondrocytes.
That is, mature cartilage cells are called chondrocytes.
They occur, either singly or in groups, within spaces called lacunae (sing. lacuna)
in the matrix.
The surface of most of the cartilage in the body is surrounded
by a membrane of dense irregular connective tissue called perichondrium.
This is important to remember especially because
(unlike other connective tissues), cartilage contains no blood
vessels or nerves - except
in the perichondrium.
There are three different types (structures) of cartilage
that have slightly different structures and functions.
They are hyaline
cartilage, fibrocartilage,
and elastic cartilage,
described seperately in the sections
below:
Hyaline Cartilage
1.0 Where in the body is hyaline cartilage tissue ?
Hyaline cartilage is the most abundant of the three
types of cartilage.
It is found in many locations in the body,
including:
- Bronchi; Bronchial Tubes; Costal
Cartilages; Larynx (voice-box); Nose; Trachea
- Covering the surface of bones at joints - especially in areas
where damage due to wear may lead to osteoarthritis incl.
e.g.
the ends
of the long bones, and also the anterior
ends of the ribs.
- Embryonic skeleton (i.e. in the fetus).
2.0 The Structure of hyaline cartilage
tissue
Hyaline cartilage consists of a bluish-white, shiny ground
elastic material with a matrix of chondroitin sulphate into
which many fine collagen fibrils are embedded. It contains
numerous
chondrocytes.
See the diagrams of the structure of cartilage tissue.
3.0 The Functions of hyaline cartilage tissue
Hyaline cartilage tissue provides smooth surfaces,
enabling tissues to move/slide easily over each other, e.g.
facilitating
smooth movements at joints. It is also provides flexibility
and support.
Fibrocartilage
1.0 Where in the body is fibrocartilage tissue ?
Examples include:
- Calli (sing. callus),
which is the tissue formed between the ends of the bone at
the site of a healing fracture
(bloodclot -> granulation tissue -> cartilage -> bone);
- Intevertebral
discs (i.e. the discs between the vertebrae
of the spine);
- Menisci (cartilage pads) of the knee joint.
- Pubic symphysis, which is the position at which the hip bones
join at the front of the body.
- Also in the portions of the tendons that
insert into the cartilage tissue, especially at joints.
2.0 The Structure of fibrocartilage
tissue
Fibrocartilage is a tough form of cartilage that consists
of chondrocytes scattered among clearly visible dense bundles
of collagen
fibres
within the matrix. Fibrocartilage lacks a perichondrium.
See the diagrams of the structure
of cartilage tissue.
3.0 The Functions of fibrocartilage tissue
Fibrocartilage tissue provides support and rigidity to
attached/surrounding structures and is the strongest of
the three types of cartilage.
Elastic Cartilage
1.0 Where in the body is elastic cartilage tissue ?
- Auditory (Eustachian) Tubes;
- External Ear (Auricle);
- Epiglottis (the lid on the top of the larynx).
2.0 The Structure of elastic cartilage
tissue
In elastic cartilage, which is yellowish in colour, the cartilage
cells (chondrocytes) are located in a threadlike network of
elastic
fibres within
the matrix of
the cartilage.
A perichondrium is present.
See the diagrams of the structure
of cartilage tissue.
3.0 The Functions of elastic cartilage tissue
Elastic cartilages provides support to surrounding structures
and helps the define and maintain the shape of the area in
which it is present, e.g. the external ear.
See also the related page about The
Structure and Functions of Bone Tissue.
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