B6.3.8 Flashcards
What is the main barrier to infection
Is your skin
If your skin is damaged what can happen
Pathogens can enter your body
To prevent microorganisms entering the skin what happens (blood)
The skin seals a cut as quickly as possible by forming a scab
What else do scabs stop
Stop you from losing too much blood
What is essential for the blood to clot
Platelets are essential for helping the blood to clot
What is the process of how scabs are formed
1) The skin is cut and starts to bleed
2) Platelets change the blood protein fibrogen into fibrin. This forms a network of fibres in the cut
3) Red blood cells are trapped in the fibres. This forms a blood clot
4) The clot hardens to form a scab. This keeps the skin clean and gives it time to heal. In time the scab falls off.
How does the skin prevent microorganisms from entering
Physical barrier. The dry, dead, outer cells are difficult for microorganisms to penetrate. The swear glands produce oils that help to kill microorganisms.
How does the acid in the stomach prevent microorganisms from entering
Kills pathogens present in contaminated food or drink
How does the cilia and mucus in airways prevent microorganisms from entering
Sticky mucus traps microorganisms. The cilia then move the mucus up to the throat, where it’s swallowed.
How do nasal hairs prevent microorganisms from entering
Keep out dust and larger microorganisms
How do tears prevent microorganisms from entering
Contain lysozymes, enzymes that destroy bacteria
What are phagocytes
These cells engulf microorganisms. They then make enzymes that digest the microorganisms.
What are lymphocytes
They make antitoxins or antibodies
What are antibodies
Proteins that bind to antigens on the surface of microorganisms. Once bound, the pathogen can be ingested by a phagocyte cell and destroyed.
What does each antibody bind to
It binds to only one type of antigen and therefore one typeof microorganism. Every time a new type of microorganism enters the body a different lymphocyte makes a new antibody to fight it.
