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6.3 Defence against infectious disease
IB Syllabus
21
Biology
11th Grade
05/21/2015

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Term
What are Pathogens
Definition
a microorganism or virus that causes a disease
Term
Name a disease caused by bacteria
Definition
Bubonic plague, Leprosy, Cholera and Tuberculosis
Term
Name a disease caused by fungi
Definition
Ringworm, Thrush and Athlete’s foot
Term
Name a disease caused by protozoa
Definition
Malaria, Leishmaniasis, Sleeping Sickness and Amoebic Dysentery
Term
Name a disease caused by worms
Definition
Schistosomiasis, Elephantiasis and Onchocerciasis
Term
What is the first line of defence in the immune system, and what does it protect?
Definition
the skin = tough, physical barrier against entry of pathogens and physical damage.
Term
What is mucus for as a medium of defence in the body?
Definition
a physical barrier because pathogens and other harmful particles are trapped in it and either swallowed or expelled
Term
What stops the blood flowing out of a wound, how is it useful against pathogens?
Definition
Blood clotting, also keeps out pathogens temporarily until new tissue forms.
Term
What is the difference between erythrocytes and leucocytes
Definition
erythro = red blood cells
leuco = white blood cells
Term
What stimulates the clotting factors
Definition
platelets in the bloodstream
Term
What is the function of the enzyme thrombin
Definition
converts the soluble protein fibrinogen into the insoluble fibrin. The fibrin traps more platelets and also blood cells to form a scab.
Term
Second line of defence: what do white blood cells - specialised phagocytes do?
Definition
identify pathogens and ingest them by endocytosis.
Term
What is pus?
Definition
when phagocytes squeeze out through pores in the walls of capillaries and move to the site of infection, resulting in the formation of a white liquid
Term
What is an antigen?
Definition
a large molecule (protein, glycoprotein, lipoprotein or polysaccharide) on the outer surface of a cell. All living cells have these antigens as part of their cell membrane or cell wall.
Term
What do antibodies do?
Definition
bind to an antigen on a particular pathogen. when a B lymphocyte white blood cell identifies an antigen, they clone plasma cells t produce antibodies to destroy the phagocytes, which they then do
Term
The white blood cells that produce antibodies are called:
Definition
B lymphocytes, produce just one type of antibody
Term
What is a memory cell?
Definition
a plasma cell that remains after an infection came, remain inactive unless the body is infected again to produce antibodies
Term
What are T cells
Definition
helpers in the production of antibodies
Term
What is the effect of HIV on the immune system.
Definition
virus destroys helper T-cells. destroys lymphocytes and antibodies cannot be produced. Without functioning immune system, body is vulnerable to pathogens that would normally be controlled easily
Term
what are antibiotics for?
Definition
to block processes that occur in prokaryotic cells but not in eukaryotic cells, like bacteria (prokaryotes)
Term
Why can virusses not be treated with antibiotics?
Definition
lack having their own metabolism, so antibiotics cannot stop any processes.
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