IB Biology 6.3

Defense against infectious disease
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Terms in this set (...)

Define pathogen
Any living organism or virus capable of causing a disease.
Explain why antibiotics are effective against bacteria but not against viruses.
Antibiotics work on bacteria because they take advantages between their prokaryotic cells by preventing certain metabolic processes, whereas viruses take over the host cell, so we don't want to attack our own body by preventing any metabolic pathways.
Outline the role of skin and mucous membranes in defense against pathogens.
Skin acts as a barrier to pathogens while mucus membranes trap pathogens with mucus, preventing them from going any further.
Outline how phagocytic leucocytes ingest pathogens in the blood and in body tissues.
Phagocytic leucocytes ingest pathogens in blood and in body tissues by surrounding pathogens and engulfing them, then they're broken down by lysosomes
Distinguish between antigens and antibodies.
Antigens - foreign proteins
Antibodies - protein molecules that respond to a specific type of pathogen
Explain antibody production
1. A specific antigen type identified
2. Specific B lymphocyte binds to antigen
3. B lymphocytes clone themselves to produce fast
4. B lymphocytes begin antibody production
5. Antibodies circulate bloodstream to find antigen match
6. Antibodies help eliminate pathogen
7. Some cloned B lymphocytes remain in bloodstream and give immunity from a 2nd infection by the same pathogens (memory cells)
Outline the effects of HIV on the immune system
HIV destroys cd-4 T cells, which impairs the body's ability to fight pathogens
Discuss the cause, transmission, and social implications of AIDS
Cause - RNA based virus attacks cd-4 T cells
Transmission - sexually, blood - to - blood contact
Social implications - first known as the "gay" disease, however there are more heterosexuals with the disease than homosexuals and its starting to reach crisis epidemic proportions in Sub-Saharan Africa