Name two professional phagocytes of the body
Neutrophils and macrophages
Name two of the body’s anti-bacterial molecules
Defensins and lysozyme
How are phagocytes activated? (3)
By toll-like receptors
By complement proteins (C3a and C5a)
Name two opsonins
C-reactive protein
C3b
What is the membrane attack complex initiated by?
What is it?
C9 molecules are assembled by C5b, C6, C7 and C8 to create a hole in the microbial membrane
What secretes sebum?
What does it contain?
Sebaceous glands secrete sebum
Contains acids and defensins (disrupts bacterial membranes)
How do phagocytes recognise bacteria? Eg?
By pattern recognition receptors (recognise patterns commonly found on microbes)
Eg toll-like receptors
Activated phagocytes have-
Increased metabolic rate
Show enhanced abilities to seek out and kill micro-organisms
Secrete cytokines
What do complement proteins C3a and C5a do?
Activate phagocytes and attract inflam cells by chemo taxis and de granulate mast cells
Which cells respond instantly to threat? And how?
Mast cells
Already in tissues
By degranulation
What do mast cell granules contain?
Histamine, prostaglandins and chemo tactic factors for eosinophils and neutrophils
Name 5 triggers for mast cell degranulation
Trauma Hot/cold Some chemicals Activated C3a and C5a Various cytokines
How is the growth of yeasts and other bacteria restricted in the urinary tract?
By friendly bacteria producing lactic acid and proponoic acid to lower pH
4 steps in phagocytosis
Recognition, adherence, engulfment, destruction
What are interferons?
Natural antiviral agents that act internally to protect the infected cell
Also is secreted and interacts with receptors on neighbouring cells
Histamine causes
Vasodilation
Increased capillary permeability
Pain
Contraction of smooth muscle
What do activated mast cells secrete?
Preformed mediators (histamine, proteases, cytokines, serotonin, heparin) Prostaglandins, leukotrienes, platelet activation factor, eiosinophil chemotactic factor
What do prostaglandins do?
Vasodilation, platelet aggregation, pain
How do natural killer cells recognise ‘self’?
Using MHC class 1 Cancerous and virally infected cells won't express it
What does MHC stand for?
Major histocompatibility complex
Where are MHC 1 and 2 found?
1- all nucleated cells
2- immune system cells
Why are MHC 1 antigens important?
They define ‘self’
Many different genes and combinations
Donor organs need to match as many MHC molecules as poss to avoid rejection
How do natural killer cells kill abnormal cells?
By releasing PERFORIN which perforates target cell membrane
How to eosinophils kill?
By respiratory burst O2 and release of toxic proteins
What do eosinophils kill?
Large parasites (helminths) that are too big to be phagocytosed