4.2 Phagocytosis, Complement and Oedema

Question 1

How is phagocytosis initiated by a macrophage?

Answer 1

Pattern recognition receptors (PRR) on macrophage recognise specific Pathogen-associated molecular patterns (PAMPs)

Question 2

Describe the two complement pathways

Answer 2

1) Classical = C1 binds to Ag-Ab complex = C1 activated

2) Alternative = C3b reacts with Ag = activated

Question 3

What does complement lead to essentially after the two pathways have been activated?

Answer 3

The same thing with both:

• Inflammation
• Destroys cells
• Participates in opsonisation

Question 4

What is oedema and compare it to lymphoedema?

Answer 4

Accumulation of an excessive amt of watery fluid in cells, tissues or serous cavities.

Lymphoedema is swelling as a result of obstuction of lymphatic vessels or lymph nodes, and hence accum of large amts of lymp in the affected region. It’s usually non-pitting as fibroblasts deposit extracellular matrix.