SCIE2100 Lecture Notes - Lecture 2: White Blood Cell, Pus, Antibody
29 May 2018
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Line of defences
Tuesday, 6 March 2018
10:05 AM
When micro-organisms enter the body, they release toxins. These toxins damage cells, which then
causes the symptoms of a disease.
FIRST LINE OF DEFENCE
• Skin - dead cells
o Lots of good bacteria on your skin - help fight the invaders.
• skin
• chemicals in tears
• chemicals in sweat
• stomach acid
SECOND LINE OF DEFENCE
• White blood cells / leucocytes
o Travel in your blood to the site of the infection, coverage on the pathogens, digest them
and engulf their remains. Dead cells are left behind and form the discharge called pus.
THIRD LINE OF DEFENCE
• Antibodies
o Processed in acquired immunity
o They float around in the blood and attach to a specific part of the pathogen, which is
called an antigen.
o The antibody disables the pathogen, which is then easily consumed by WBCs, thus
destroying the threat.
o A particular antibody will act against the antigens on only one type of pathogen. The
body keeps creating antibodies
o The antibodies will only be able to fight the pathogen if they are created by the body.
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