3.1.6 Human Defence Systems Flashcards
Human barriers against pathogens (3p)
- Skin
- Nose
- Stomach
Stomach (Human barriers against pathogens)
Stomach acid kills pathogens
Skin (Human barriers against pathogens)
- Stops pathogens from getting in
Nose (Human barriers against pathogens)
- Nose hairs prevent things from getting in
How does bacteria make us feel ill?(2p)
Produce toxins
Damage cells
How do viruses make us feel? (2p)
- They takeover and control host cells
- They damage cells when they reproduce
Types of white blood cells? (2p)
Lymphocytes
Phagocytes
Immune system
The body system that recognises and destroys foreign cells
Phagocytosis
When a pathogen is engulfed, then destroyed by a phagocyte
Antibody
A protein produced by lymphocytes that bind to and counteract antigen
Antitoxen
A protein produced by lymphocytes, which bind to and counteract toxins
Purpose of lymphocytes
Produce antibodies/antitoxins that bind to pathogens, targeting them for destruction
Purpose of phagocytes
They engulf and destroy bacteria by phagocytosis
How does the chances of getting an infection increase if blood doesn’t clot properly?(2p)
- Allows pathogens into bloodstream through open wound
- Blood clotts prevent pathogens entering
How does the chances of getting an infection increase if the number of white blood cells fall?(3p)
- White blood cells destroy pathogens
- If there are less, it means fewer pathogens will be destroyed,
- This increases the likelihood of infection
How the immune system protects against disease (4p)
1) Pathogen enters blood stream
2) Lymphocytes produce antibodies/antitoxens
3) Antibodies bind to antigens/antitoxen binds to toxin on pathogen
4) Phagocytosis of pathogen/toxin
