2. Cartilage exists in the body as three types:
• Hyaline
• elastic
• fibrocartilage
3. • Hyaline cartilage
• is found mainly in association with the skeletal system,
as articular cartilage, costal cartilage or growth plate,
though it does also occur in extra-skeletal sites, such as
the larynx, trachea, bronchi and nose. It is characterized
by its type II collagen and high concentration of
aggregating proteoglycan.
• Elastic cartilage is found mainly in the ear and
epiglottis, and differs from hyaline cartilage by the
presence of substantial amounts of elastic fibers.
• Fibrocartilage is also associated with the skeletal
system, with the best examples being the meniscus of
the knee and the anulus fibrosus of the intervertebral
discs. Unlike the other cartilage types, it is composed
principally of type I collagen and has a lower
proteoglycan content
4.
5. Composition
• Mature cartilage contains about 5% of its
volume as cells, the remainder being
extracellular matrix.
• There is normally no mineral, and organic
material accounts for about 30% of the matrix,
with the remainder being water.
• About 60% of the organic material is collagen,
25% is proteoglycan and the remainder is a
variety of matrix proteins.
7. Collagens
• Collagens consist of 3 polypeptide chains that
form a triple helix along at least part of
their length.
• They can be divided into fibrillar collagens
(types I, II, III, V and XI), which form the
framework of the tissue, and non-fibrillar
collagens.
8.
9. • Fibrillar types II and XI collagen, with the
former being most abundant, and the non-fibrillar
type IX collagen.
• Type IX collagen resides on the surface of the fibrils,
and is thought to facilitate interaction between the
collagenous framework of the tissue and the
interspersed proteoglycan.
• Growth plate cartilage is unique in also containing
the non-fibrillar type X collagen, which is thought
to play an integral role in the mineralization
process.
• Fibrocartilages contain type I collagen as their
predominant fibrillar collagen, in common with
most other connective tissues.
10.
11.
12.
13.
14. Adhesive proteins
• Adhesive proteins provide the connections
between the various components of the
extracellular matrix.
• Important representatives include laminin and
fibronectin.
• These multifunctional proteins simultaneously
bind to several other types of matrix component.
• Cells attach to the cell surface receptors in the
ECM with the help of the adhesive proteins
15.
16. Proteoglycans
• Proteoglycans are giant molecule complexes
consisting of carbohydrates (95%) and proteins
(5%)
• Their bottlebrush-shaped structure is produced
by an axis consisting of hyaluronate. This
thread-like polysaccharide has proteins
attached to it, from which in turn long
polysaccharide chains emerge. Like the central
hyaluronate, these terminal polysaccharides
belong to the glycosaminoglycan group
17.
18. • Proteoglycans are composed of two basic
molecules―core protein and
glycosaminoglycans.
• The core protein may contain serine residues;
these residues act as a point of attachment to
which different glycosaminoglycans attach.
• The glycosaminoglycans attach to the core
proteins perpendicularly and give rise to a
brush-like structure.
19. • Glycosaminoglycans are long, unbranched
molecules that contain repeating disaccharide
units of a uronic acid (either D-glucuronic acid
or L-iduronic acid) and an amino sugar (either
N-acetylglucosamine, or N acetylgalactosamine).
20.
21.
22. • Proteoglycans can be classified on the basis of
glycosaminoglycans they possess. There are four
basic types of glycosaminoglycans: chondroitin
sulfate (CS), heparan sulfate, dermatan sulfate
(DS), and keratan sulfate (KS).
23. Proteoglycans in Cartilage
• The extracellular matrix of cartilage contains
five well-characterized proteoglycans. Out of all
the proteoglycans present, aggrecan is the most
abundant.
• It has more than hundred chondroitin sulfates
and keratan sufaltes. They interact with
molecules of hyaluronan to form large
aggregates.
• Aggrecan provides cartilage with the property to
bind with water to form hydrated matrices.
These molecules act as fillers between the cell
spaces.
24. Chondrocytes
• Chondrocytes are the only cells found in
healthy cartilage .
• They produce and maintain the cartilaginous
matrix, which consists mainly
of collagen and proteoglycans.
• Although the word chondroblast is commonly
used to describe an immature chondrocyte, the
term is imprecise, since the progenitor of
chondrocytes
28. Types of Cox
• Different types of prostanoids can be easily synthesized
in the body by using an enzyme named as
cylcooxygenase (COX).
• These prostanoids including
prostaglandins, prostacyclin and thromboxane are
important biological mediators that play crucial role in
the development of pain and inflammation in the body.
• So it is possible to get relief from pain and inflammation
by inhibiting the COX enzyme.
• There are three different types of COX enzymes such as
COX1, COX2 and COX3. They are similar in different
aspects and have some differences too.
29. Prostanodis
• Prostanoids are a subclass of eicosanoids
consisting of the prostaglandins (mediators of
inflammatory and anaphylactic reactions), the
thromboxanes (mediators of vasoconstriction),
and the prostacyclins (active in the resolution
phase of inflammation.)
30. • COX-1 is also called as constitutive enzyme
because it is produced by a cell under all types of
physiological conditions.
• The amount at which constitutive enzymes are
produced remain constant without regard of
substrate concentration and physiological
demand.
• On the other hand COX-2 is an inducible enzyme
as it is produced under certain specific conditions
like inflammation.
31. Functions
• COX-1 play important role in housekeeping such
as it protects gastric mucosa, regulate gastric
acid and maintain normal functions of the
kidney by stimulating prostaglainds.
• COX-2 is involved in the synthesis of
prostaglandins that causes pain and
inflammation in the body.
32.
33. • COX-1 enzymes are protective in nature and
therefore are useful for the body. So there is no
need to inhibit them
• COX-2 enzymes play an important role in
inflammation. So it is desirous to inhibit COX-2
enzymes.
34. COX and arthritis
• Joint inflammation in all forms of arthritis is
associated with increased production of COX-2
(cyclooxygenase-2) in response to cytokine
stimulation of synovial cells.
• Prostaglandins produced by the action of COX-2
mediate the features of inflammation.
• The anti-inflammatory role of NSAIDs
(Nonsteroidal anti-inflammatory drugs ex.
Aspirin, ibuporfen) is due to their inhibition of
COX-2.
