Extracellular Matrix

Question 1

Function of the ECM?

What is it composed of?

What produces the fibrous proteins?

What is Ground Substance?

What is the main GAG in the ground substance?

Answer 1

• Provides a scaffold for cells, Reaction site for chemical processes, Homeostasis, Storage
• Water, Fibrous proteins (Collagen, Elastin), Ground substance, Minerals
• Fibroblasts
• Gel-like substance made of GAGs, which are water absorbent due to high -ve charge and are long chains; Mix of GAG types allow ECM to regulate the size/type of molecules that can pass through it
• Hyaluronan (Hyaluronic acid)

Question 2

Collagen:
What does it provide? Where is it found?

What is its structure? What is the repeat amino acid sequence in it?

Where is it produced?

How is it produced?

Common disorders:
What is Osteogenesis Imperfecta? Features?

What is Elhers-Danlos Syndrome? Features?

Answer 2

• Most abundant protein in body, Provides tensile strength e.g. bones, tendons
• Triple helix of α-chains; the amino acid sequence is a repeat of Glycine-Proline-Hydroxyproline
• RER as single stands
• Single stands come together to form a triple helix = Procollagen; ends removed to become Tropocollagen, which comes together to form fibrils, and then forms the collagen fibre
• • Genetic; Type-1 Collagen Deficiency
  • Brittle bones, Weak lung tissue, Blue-tinged eyes, and Bowed legs (like in Rickets)
• Hypermobility in joints, Stretchy skin, Easily ruptured blood vessels

Question 3

Elastin:
What does it provide? Where is it found?

Where is it produced?

How is it produced?

Common disorder:
What is Pulmonary Emphysema? What’s it due to?

Answer 3

• Provides elasticity; help return compressed object to its original shape e.g. skin, liver, blood vessels
• RER
• Made in RER as Tropoelastin, which attaches to a glycoprotein
• Lack of elasticity in lung tissue
  o Due to deficiency of a1-anti-trypsin (inhibits Elastase) = Overproduction of Elastase = Less elastin and Stiffening of lung