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Chapter 5.2 - defence mechanisms (Defence mechanisms (responses involve a…
Chapter 5.2 - defence mechanisms
infection
an interaction between the pathogen and the body's various defence mechanisms
sometimes it overwhelms the defences and the individual dies
sometimes the body's defence mechanisms over whelm the pathogen and the individual recovers from the disease
having overwhelmed the pathogen, the bodys defences are better prepared for a second infection from the same pathogen and so can kill it before it causes harm
This is known as
imunity
Defence mechanisms
responses involve a type of white blood cell called a lymphocyte and take 2 forms
cell-mediated responses involving T lymphocytes
humoral responses involving B lymphocytes
recognising your own cells
each type of cell has specific molecules on its surface that identify it
proteins are most important because they have an enormous variety and a highly specific tertiary structure.
it is this variety of specific 3D structure that distinguishes one cell from another
it is the protein molecules which usually allow the protein system to identify :
non-self material
abnormal body cells e.g. cancer cells
pathogens
specific
- response is slower and specific to each pathogen
Physical barrier e.g. skin
phagocytosis
Non specific
- response is immediate and the same for all pathogens
humoral response - B lymphocytes
cell-mediated response - T lymphocytes