Defence systems Flashcards
Physical barriers - Skin
Covers the whole body to stop pathogens from entering.
Adapted to immediately form a scab when cut
Eyes
Produced tears containing enzymes to kill off any pathogens
Nose
Internal hairs to trap pathogens
Produces mucus that traps pathogens and is removed when blowing the nose
Trachea/ bronchi
Lined with cells with cilia (tiny hairs)
Waft the pathogens away from the lungs to the stomach
Stomach
Produces hydrochloric acid that kills off micro organisms from the trachea or food
Antibiotics
Substances that kill off or stop the growth of bacteria by damaging them but not the host’s cells
Can’t be used for virus as they may damage the host cell.
Examples of antibiotics
Penicillin - formed from penicillium mould. Founded by Alexander Fleming
Amoxicillin
Immune systems
Destroys pathogens and any toxins they produce
Protects us incase the same type of pathogen invades us again in the future
Phagocytosis
Phagocyte (WBC) surrounds pathogen
Enclosed it in a cytoplasm
Secretes enzymes to destroy it
(Engulfs)
Antibodies
Proteins molecules that white blood cells produce
Extremely specific to each pathogen
They can remain in the body for a long time in case we get infected by that pathogen in the future
How do antibodies work?
WBCs produce antibodies that stick to the pathogens
This triggers the pathogens to be destroyed
Or releases antitoxins
Antitoxins
Bind to toxins produced by bacteria to stop them from spreading or damaging cells
Neutralises their toxic effects
How does vaccination work?
Vaccines contain dead or inactive pathogens
Injected into the body
White blood cells are stimulated to produce specific antibodies against it
Later, if an alive pathogen enters the blood the white blood cells can produce the correct antibodies quickly preventing infection and illness
Given that they’ve already been stimulated to make the specific antibodies
Antigens
Protein on the surface of a pathogen that WBCs detect
What does it mean that antibodies are specific?
They are only effective against a certain pathogen.
Therefore if you are infected with measles, measles specific antibodies are produced and won’t fight against other pathogens
