extracellular matrix Flashcards
what is the ECM?
the non cellular component present within all tissues and organs
what is found inside the ECM?
collagen and elastin
roughly how many different proteins make up the ECM?
300
mainly what is the ECM made of?
water proteins and polysaccharides
what are the 2 main types of ECM
interstitial connective tissue matrix and basement membrane
what is the function of the interstitial connective tissue matrix?
surrounds cells and provides structural scaffolding for tissues
what is the function of the basement membrane?
specialised form of the ECM which separates the epithelium from the surrounding stroma
what are some functions of the ECM?
-provides mechanical and structural support
-tensile strength (resist mechanical force)
-determines cellular movement
what are the 2 groups of molecules that the ECM can be divided into?
fibrous proteins (collagens and elastin) and ground substance (the remainder)
what are the 5 classes of molecules found in ECM?
-collagens
-elastin
-proteoglycans
-hyaluronan
-other glycoproteins
collagen
fibrous protein family, main function is to provide tensile strength so can resist a large amount of force. secreted into ECM as polypeptide chains (triple helix) triple amino acid go fly followed by two other amino acids
what type of collagen is found in the basement membrane?
collagen IV
elastin
structural protein arranged as fibres, abundant in tissues that require stretch and recoil properties. assembly into functional fibres requires the presence of a structural glycoprotein - fibrillin which gets incorporated into the elastin fibre
what is ground substance?
clear, gelatinous like substance that fills the space between fibres and cells in connective tissue, mostly water but contains very large molecule, highly negatively charged and therefor attract water.
what is the basement membrane?
a thin, tough sheet of ECM in a mat like arrangement, underlies and supports epithelial cells and is produced by epithelial cells
what are the functions of the basement membrane?
-support
-binding to underlying connective tissue
-mbarrier to downward growth
-path for cell migration
-permits flow of nutrients
-determines cell polarity
what is the ECM produced by?
is surrounding cells
what are some examples of disease when the basement membrane does not function properly?
cancer, diabetes mellitus, epidermolysis bullosa, goodpastures syndrome
which molecule allows tumour cells to pass basement membrane?
matrix metalloproteinase
what is cartilage?
-synthesised by chondrocytes
-type II collagen
-chondroitin sulphate
-keratin sulphate
-hylauronic acid
what makes up cartilage proteoglycan?
aggrecan and hylaruronic acid
what are the three types of cartilage?
-hyaline
-elastic
-fibrocartilage
what distinguishes hyaline cartilage?
-few visible collagen fibres
-avascular
-has perichondrium (except articular cartilage)
-found in septum, articular surfaces, sternal ends of ribs, epiphyseal growth plate
what distinguishes fibrocartilage?
-abundant collagen fibres
-avascular
-no perichondrium
-found in IV discs, pubic synthesis
what does avascular mean?
lack of blood vessels
what is perichondrium?
the connective tissue that envelopes cartilage when it is not at a joint.
what is the function of the perichondrium?
protect bones from injury and damage,
what distinguishes elastic cartilage?
-contains elastic fibres
-avascular
-has perichondrium
-found in external ear, auditory tube
what does over production of the ECM result in?
fibrosis
What is the structure of collagen I?
Can form parallel collagen fibrils that confer strength
What is the structure of collagen IV?
Thin mesh crude found in basement membrane
Where is type I collagen found?
Dermis, tendons, ligaments, bones, fibrocartilage
Where is type 2 cartilage found?
Hyaline cartilage
Where is type III collagen found?
Liver, bone marrow, lymphoid organs; granulation tissue eg reticulim
Where is type IV collagen found?
Basement membranes
Where is collagen type V found?
Linker to basement membrane, cornea
Which tissues are rich in elastin?
Ones that require recoil, lungs, bladder, blood vessels ect
What is needed to assemble elastin into functional fibres?
Structural glycoproteins- fibrillin
What makes up ground substance?
Non fibrous molecules, amorphous, colourless, gelatinous material that fills the space between fibres and cells in connective tissues.
What makes up glycoproteins p?
GAGs (glycosaminoglycans) which link together with a core protein
What is hylauronic acid best known for?
Attracting water, found in synovial fluid in joint
What makes hylauronic acid so fit to bind so much water?
Highly polar structure
Where is aggrecan located?
Cartilage
Where is perclean located?
Basement membrane
Where is syndecan located?
Cartilage
Where is decorin located?
Widespread in connective tissue
What is fibrillin?
Controls deposition and orientation of elastin
What is fibronectin?
Linker role in basement membrane; organises ECM and participates in cell attachment to BM. Provides imitial matrix for keratinocyte migration
What is laminin?
Primary organiser of BM. Role in maintaining integrity of dermo-epidermal junction
What is the principal cell in the production of the ECM?
Fibroblasts
What causes good pastures syndrome?
Autoantibodies to collagen IV destroy BM in glomerulus and lung
Where is hyaline cartilage found?
Nasal septum, larynx, sternal ends of ribs, epiphyseal growth plate
Where is fibrocartilage found?
IV discs, pubic symphysis
Where is elastic cartilage found?
External ear, epiglottis
what makes up the ECM?
COLLAGEN IV
LAMININ
NIDOPEN
PERLECAN
