Extracellular Matrix Flashcards
ECM
complex network of proteins and polysaccharides that are secreted locally by cells and remain closely associated to provide structural, adhesive and biochemical support
location of ECM
basement membrane, bone, tendon, subcutaneous fat etc (vary in ratio of components)
ECM contains (acellular)
-fibres: collagen and elastin
-ground substance: proteoglycans, glycosaminoglycans and glycoproteins
funtion of ECM
-mechanical and structure support
-tensile strength
-anchors cell (cell-ECM junction)
-influence embryonic development
-pathway for cell migration
ECM macromolecules
collagen, elastin, proteoglycans, hyaluronan (GAG) and glycoproteins
skin and blood vessels
high ratio of elastin
-resilience
cartilage
high ratio of collagen
-tensile strength
bone
calcified collagen
-incompressible
fibroblasts produce
collagen
collagen secretion
out in the ECM by exocytosis
collagen I
dermis, tendons, ligaments and bones
collagen II
hyaline cartilage
collagen III
liver, bone marrow, lymphoid organs: also in granulation tissue aka reticulin
collagen IV
basement membranes
collagen V
linker to basement membrane
elastin
structural protein arranged in fibres and surrounded by glycoprotein fibrillin
- form fibrous network within connective tissue
ground substance
amorphus, colourless and fills space between fibres and cells
- provides medium for exchange of substances
- consists of GAGs which form proteoglycans
GAGs function
trap water which makes them jelly like
- resistance to compressive force
ECM water content
90%
aggrecan
proteoglycan found in cartilage
GAG: chondroitin sulphate and keratan sulphate
perlecan
proteoglycan located in basement membrane
GAG: heparan sulphate
syndecan
proteoglycan located in cartilage
GAG: chondroitin sulphate and heparan sulphate
decorin
located in connective tissue
GAG: chondroitin sulphate and dermatan sulphate
hyaluronan (GAG)
synovial fluid
-hyaluronic acid
chondroitin sulphate (GAG)
cartilage
keratan sulphate (GAG)
cartilage
heparan sulphate (GAG)
basement membrane
hyaluronic acid
viscous and binds cells together
- lubricates joints
hyaluronidase enzyme
produced by WBCs and sperm
- breaks down hyaluronic acid
- aids spread and movement
glycoprotein fibrillin
controls deposition and orientation of elastin
glycoprotein fibronectin
linker role in basement membrane; organises ECM and attaches cell to BM
glycoprotein laminin
primary organiser of basement membrane layer
glycoprotein entactin
linker role in BM
tenascin
linker role in connective tissue
proteoglycan synthesis
in the rER then to golgi where polysaccharides as disaccharide repeats (GAGs)
- delivered to ECM by exocytosis
