Extracellular matrix Flashcards
What is the extracellular matrix?
Any substance produced by cells and secreted into the extracellular space within the tissues
What two main functions does the ECM have?
Structural and motility
What two structural roles does the ECM have?
it provides physical support for cells, and a linkage between different cells or tissues
What two roles regarding cell motility does the ECM provide?
A substrate on which the cells can move, and cues that guide the direction of movement
How are cells usually organised in animals?
Epithelial tissue and connective tissue
Cell contact in epithelial tissue?
Cells are in direct contact with one another
Cell contact in connective tissue?
Cells are not in direct contact with one another
What is the scant ECM made up of?
layers closely bound to one another to form protective sheets
What does the basal lamina do?
Provides a base for the cells to sit on and acts a a molecular sieve and substrate for migrating cells
What cells are scattered through the ECM?
Fibroblasts
What are fibroblasts?
Cells that contribute towards the formation of connective tissue
How is the ECM composed?
Collagen fibres cross-linked by accessory proteins in a matrix of proteoglycans
What are proteoglycans made up of?
proteins and polysaccharides
What kind of substance do collagen fibres form?
A mesh
ECM relationship with plant cells?
All plant cells are surrounded by the ECM
What is the ECM in plant cells?
The cell wall
What are the three layers of the plant cell wall?
Middle lamella, primary cell wall, plasma membrane
What does the plant cell wall consist of?
Cellulose fibres cross linked with hemicellulose in a matrix of highly branched polysaccharides
What are the fibres in plant ECM?
Polysaccharides
What are the fibred in animal ECM?
Proteins
Which proteins types are in the animal ECM?
collagens and elastins
What kind of forces doec collagen resist?
Tensile forces
What % of total protein mass does collagen account for?
25%
Why do different tissues contain different types of collagens?
Helps to control and shape the properties of the tissues
What makes up the collagen fibrils?
Single collagen polypeptide molecules
How many strands does a collagen fibril have?
Three single collagen polypeptides
What kind of reaction do three single collagen polypeptide undergo to form a collagen fibril?
Condensation
How do the collagen fibrils join together to become a collagen fibre?
They self assemble
What cross links collagen fibres?
Proteins (other types of collagen)
What is different to normal collagen about the collagen that forms cross-fibres?
They dont form fibres
