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How does the skin prevent entry of pathogens (3)
-Covers the body and prevents the entry of pathogens.
- has a flora of healthy microorganisms that outcompete pathogens for space on the body surface
- produces sebum (oily substance) that inhibits growth of pathogens
How do mucus membranes prevent entry of pathogens
-lines many body tracts and secretes muscus to trap pathogens'
-mucus also contains phagocytes which remove remaining pathogens
how do lysosomes prevent the entry of pathogens?
found in tears and urine
they contain hydrolytic enzymes that aid in destroying pathogens
how does expulsive reflexes prevent the entry of pathogens?
eject pathogens in airways out of our body
how does blood clotting work?
-platelets release substances that via a cascade of reactions result in soluble fibrinogen into insoluble fibrin
why is serotonin useful?
makes the smooth muscle in the walls of blood vessels contract, so they narrow and reduce the supply of blood to the area
this localises the spread of pathogens, reduce blood loss and redirect blood to more important sites
what is the inflammation response categorised as? 3x
pain
heat
swelling
what cells are activated in the inflammatory response? and what do they release
mast cells and they release histamines
what 3 things do histamines mainly do and why are they important?
widen blood vessels and make capillaries more leakier so more immune cells can travel into tissue fluid
causes swelling
induces fever and raises body temp
histamines also release cytokines? what are they and how do they help? 3x
cell signalling molecules that inform the body is under attack
increase body temp
stimulate specific immune system
signals for phagocytes to the site of infection
why are fevers useful? 2x
raises body temp so pathogens cannot reproduce as easily
specific immune system work best at higher temps
Stages of phagocytosis (5)
1. Pathogens produces chemicals that attract phagocytes
2. Phagocytes recognise antigens on the pathogen
3. The phagocyte engulfs the pathogen and encloses it into a vacuole called the phagosome
4. Phagosome combines with a lysosome and becomes phagolysosome
5. Enzymes from the lysosome destroy the pathogen
When a macrophage has digested a pathogen, what does it combine to make
Combines antigens from the pathogen with special glycoproteins called the major histocompatibility complex (MHC)
What does the major histocompatability complex (MHC) do
Moves the pathogen's antigens to the macrophages own plasma membrane, making it an antigen presenting cell (APC)
What are opsonins?
chemicals that bind to pathogens and tags them for phagocytes
