Phagocytosis Complement and Oedema

Question 1

What are the stages of phagocytosis?

Answer 1

1) Come into contact
2) Bind to receptor on pathogen
3) Engulf to make phagosome
4) Fuse to make phagolysosome
5) Lysosome breaks down pathogen
6) Residual body discharged

Question 2

What are the two ways a a phagocyte can come into contact with a pathogen?

Answer 2

Chemotaxis towards it

Or directly

Question 3

How does a lysosome break down a pathogen that has been phagocytosed (2)?

Answer 3

Low pH

Hydrolytic enzymes

Question 4

What two things can happen to the residual body after phagocytosis?

Answer 4

Form fine granules in cell or be exocytosed

Question 5

What is complement and 3 things does it do? Which immune system is it part of?

Answer 5

It is a group of serum proteins 
1)Opsonise
2) Destroy cells
3)Inflammation 
Part of innate immune system

Question 6

What are the two complement pathways and what happens?

Answer 6

Classical - C1 - activated when binds to antigen-antibody complex
Alternative - C3b - activated when binds to antigens such as bacterial cell wall. Both follow the same pathway after this.

Question 7

What is opsonisation?

Answer 7

Making pathogens more appealing to phagocytes

Question 8

What is the difference between lymph oedema and oedema? How can you tell clinically which one it is?

Answer 8

Lymph oedema is blockage of lymph vessels- doesn’t pit as contains loads of proteins

Oedema is fluid moving and staying in the interstitium from the capillaries - pits

Question 9

Why does venous hypertension cause brown leg staining?

Answer 9

Due to O2 dependent phagocytosis and haemosiderin staining