Phagocytosis, Complement & Oedema

Question 1

Name 6 phagocytic WBCs

Answer 1

Macrophages, neutrophils, basophils, eosinophils, mast cells, dendritic cells

Question 2

What is phagocytosis? What are the 7 broad steps?

Answer 2

It is engulfing and killing debris/pathogen via specialised and specific endocytosis

1) Contact between phagocyte and pathogen
2) Binding of pathogen to receptors on phagocyte
3) Phagocyte encircles and engulfs
4) Phagosome created - inside cell
5) Binds with lysosome to form phagolysosome
6) Low pH and hydroytic enzymes in lysosome degrade pathogen
7) Residual body either becomes fine granules in cytosole or exocytosed

Question 3

What is complement and what 3 functions does it have? Which type of immune system is it part of?

Answer 3

Complement is part of innate immune system, it consists of a group of serum proteins that when activated help 1) opsonise pathogens ready for phagocytosis 2) inflammation (macrophages and neutrophils) 3) breaks down cell membrane of pathogen

Question 4

What are the two pathways of complement, and which two proteins are activated? They come together in the same route after which point?

Answer 4

Classical pathway - C1
Alternative pathway - C3b

Both follow same route after C3

Question 5

What is opsonisation, why is it needed? What are two complement and two antibody examples of opsonins?

Answer 5

It is tagging of pathogens by proteins to enhance phagocytosis. Pathogens and immune cells both have - charged membranes so by using an opsonin immune cell receptors can bind to the opsonin to come in close contact with the pathogen to ingest it.

Examples: Antibody: IgG and IgA, Complement: C1 C3b

Question 6

What are the differences between oedema and lymph oedema?

Answer 6

Oedema - caused by increase in hydrostatic pressure, watery liquid, easily movable, pits, at ankles first due to gravity.

Lymphoedema - caused by blocked lymph vessels, rich in proteins, not easily movable - does not pit. Causes Papules on skin.

Question 7

Why would you get swelling in the eyelids in the morning with Nephrotic syndrome?

Answer 7

• Lax skin

- Laying flat allows build up around eyes

Question 8

Name an area of lax skin where you may get oedema

Answer 8

Genetalia

Question 9

Why does venous hypertension cause brown leg staining?

Answer 9

o2 dependent phagocytosis and haemosiderin (iron storage complex ) staining