what is the role of the immune system
identify and eliminate micro-organisms, harmful substances and cancer cells
how can we manipulative the immune system to our benefit
- immunisations
- immunosuppression and anti-inflammatory drugs
- cancer immunotherapy
what does immunotherapy do
allows immune cells to recognise, target and kill cancer cells
what are the points of entry to pathogens
- digestive, resp and urogenital systems
- skin damage
what are the routes of attack of pathogens
circulatory and lymphatic systems
how does skin act as a physical barrier to pathogens
- tightly packed, highly keratinised layered cells
- low pH and O2 tension
- sebacious glands
- oils, lysozymes, ammonia, anti-microbial peptides
describe how mucous protects against pathogens
traps pathogens that enter body cavities that come into contact with the environment and remove them via ciliary cells
commensal bacteria:
- relationship with host
- where are they
- symbiotic relationship with host
- reside at epithelial surface
how do we eliminate unwanted pathogens
coughing, sneezing, peeing, diarrhoea
natural barriers (5)
- traps
- unfavourable pH
- lysosymes
- elimination
- physical
how do we trap pathogens
mucous, earwax, cilia, hair
where are lysozymes and what do they do
- in tears and sweat
- digest bacterial cell walls
where is unfavourable pH (for pathogens in the body)
stomach acid, sweat, saliva, urine
when natural barriers are breached what cells ingest pathogens first
macrophages
how do macrophages ingest pathogens
- pinocytosis
- phagocytosis
- endocytosis
describe pinocytosis
fluid surrounding the cell is ingested
describe phagocytosis
- antigen PAMPs bind to PRRs on macrophage surface
- cup extends around antigen and pinches off creating a phagosome
- phagosome is infused with lysozymes, this kills pathogens and degrades the contents
- debris released
describe endocytosis
pathogen binds to cell receptor, cell membrane envelopes around it and it is internalised
opsonisation
coating of pathogen in soluble factors to enhance phagocytosis
what type of proteins are opsonins
CRP, C3b, IgM and IgG
what happens if the pathogen is too big for a macrophage to digest
mast cells step in and degranulate
describe mast cells degranulation
- pathogen binds to PRRs, danger/cell damage signals received
- degranulation occurs and pro-inflammatory mediators are released
- new pro-inflammatory mediators are produced
