3 - Extracellular Matrix Biology 1 Flashcards
What are fibroblasts?
cells that synthesise the ECM and collagen (most commonly found in connective tissue)
Define the ECM
a complex network of proteins and carbohydrates that fill the spaces between cells
What are the functions of the ECM? (3)
- physical support
- determines mechanical and physiochemical properties of the tissue
- influences the growth, adhesion and differentiation of the cells with which it interacts
- essential for development - tissue function and organogenesis
What is connective tissue?
ECM + component cells
it is rich in ECM
macrophages are present
What is the function of the basal lamina?
separates the epithelia from the connective tissue
From which mutation does Osteogenesis Imperfecta arise?
Type I collagen
From which mutation does Marfan’s syndrome arise?
Fibrillin 1
From which mutation does Alport’s syndrome arise?
Type IV collagen
From which mutation does Epidermolysis Bullosa arise?
Laminin 5
From which mutation does congenital muscular dystrophy arise?
Laminin 2
What are the properties of the connective tissue in the tendons and skin?
tough and flexible
What are the properties of the connective tissue in the vitreous humous?
soft and transparent
What are the properties of the connective tissue in bone?
hard and dense
What are the properties of the connective tissue in cartilage?
(found in joints - softer and more flexible than bone)
resilient and shock absorbing
Which cells make the ECM components?
fibroblasts
What is the arrangement of collagen in the tendons? What significance does this have?
layers of collagen fibrils are laid down almost parallel to one another - this give the tissue tensile strength (ability to resist stress) in 2 directions
What constitutes the triple helix in collagen?
can be comprised of one or more different types of alpha chains
- type 1 collagen - 2 α1 chains and 1 α2 chain
- types 2 and 3 collagen (only have one chain type) - 3 α1 chains
What constitutes the triple helix in collagen?
comprised of one or more different types of alpha chains
- type 1 collagen - 2 α1 chains and 1 α2 chain
- types 2 and 3 collagen (only have one chain type) - 3 α1 chains
How do the individual helices form collagen?
- individual triple helices come together to form fibrils
- fibrils come together to form collagen fibres
Give the order of events in collagen biosynthesis
- synthesis of pro-α chain
- hydroxylation of prolines and lysines
- glycosylation of hydroxylysines
- self assembly of 3 pro-α chains
- procollagen triple helix formation
- secretion
- cleavage of propeptides
- self assembly into fibrils
- aggregation pf collagen to form a colagen fibre
What enzymes hydroxylate the residues on the pro-α chains?
What do they require to function?
proplyl and lysyl hydroxylases,
require vitamin C and iron to function
What does a deficiency of vitamin C cause?
scurvy:
there is a lack of proper collagen hydroxylation, so they can’t aggregate together properly and form firm collagen fibres which affects the tissue stability
How are elastic and collagen related?
they are often interwoven to limit the extent of stretching
Where can elastin be found in the body?
skin, blood vessels and lungs
What is the basement membrane?
- flexible, thin mats of ECM that surrounds muscle, peripheral nerves, fat cells and underlie most epithelia
- in the kidney glomerulus, it prevents macromolecules from going form the blood into the nephron
NOTE: diabetic nephropathy - ECM accumulation - restricts renal filtration and causes renal failure
