Diseases and immunity Flashcards
Pathogen
disease-causing organism
Transmissible disease
a disease in which the pathogen can be passed from one
host to another.
A pathogen is transmitted
by direct contact, through blood and other body fluids.
by indirectly contact, from contaminated surfaces, food, animals and air.
Body’s defense system includes
skin, hairs in the nose, mucus, stomach acid and
white blood cells.
To prevent spreading of diseases use
a clean water supply - water from dirty rivers or lakes can contain many different
pathogens.
hygienic food preparation - bacteria can grow on the food too, houseflies have
harmful bacteria on their feet and they can land on the food to contaminate it.
good personal hygiene - we should clean our body regularly because oil, dirt and
sweat can build up on the skin and this will provide breeding ground for harmful
bacteria.
waste disposal - harmful bacteria can grow on organic waste so it must be
disposed as soon as possible.
sewage treatment - treating the water before drinking removes dirt and
microorganisms from it
Active immunity
defence against a pathogen by antibody production in the body.
Each pathogen has its own
antigens, which have specific shapes.
Antibodies
are proteins that bind to antigens leading to direct destruction of
pathogens or marking of pathogens for destruction by phagocytes.
Specific antibodies have
complementary shapes which fit specific antigens
Active immunity is gained after
an infection by a pathogen or by vaccination
Process of vaccination
weakened pathogens or their antigens are injected into the body
the antigens stimulate an immune response by lymphocytes which produce
antibodies
memory cells are produced that give long-term immunity.
Vaccination provide active immunity to
individuals and prevents pathogens from
breeding in them. If 90% of the people are vaccinated to a disease, the pathogen will
have very few places to live and grow therefore the spread of disease will decrease.
Non-vaccinated individuals will also get protection as a result of herd immunity
Passive immunity
short-term defence against a pathogen by antibodies acquired
from another individual, e.g. across the placenta and in breast milk.
A young baby’s immune system is not well developed, and so the mother’s
antibodies can protect it against any diseases to which she is immune, for the first
few months of its life.
Memory cells are not produced in
passive immunity.
