diseases and immunity (topic 10) Flashcards
what is a pathogen
A disease-causing agent such as a virus or a bacterium.
what is a transmissible disease
a disease in which the pathogen can be passed from one host to another
what are the two ways a pathogen can be transmitted
directly and indirectly
describe pathogen transmission through direct contact
through body fluids such as blood and other bodily fluids
describe pathogen transmission through indirect contact
such as from the air, through water or food, contaminated surfaces or animals.
what is meant by bodys first line of defence
The body’s initial defence against disease: non-specific physical or mechnical barriers that prevent pathogens from entering the body.
what is meant by bodies second line of defence
The immune system is the second line of defence if a pathogen passes the first line of defence, enters the body and causes an infection.
examples and explanations of first line of defence
mucus- present in the respiratory tract traps dust and pathogens. (chemical barrier)
nose hair- The hairs of the nose trap dust particles and pathogens. (mechanical barrier)
stomach acid- Acid secreted in the stomach kills microorganisms in food and water. (chemical barrier)
skin- acts as a barrier, prevents entry of pathogen (mechanical barrier)
examples and explanations of second line of defence
Once a pathogen gains entry to the body, the immune system detects and destroys pathogens.
white blood cells:
phagocytes: surround and engulf pathogen in phagocytosis
lymphocytes: prodcue antibodies proteins that attach to pathogens and either kills or marks for destruction
what are some methods to decrease spread of diseases
a clean water supply
good personal hygiene
hygienic food preparation
proper waste disposal
treatment of sewage.
what is active immunity
Immunity that develops in response to a pathogen and involves the activation of memory cells.
what is an antigen
the part of a pathogen which is unique to each type of pathogen, has a complementary shape to the antibody in the body
what are antibodies
proteins produced by lymphocytes, have a complementary shape to antigens, bind
to antigens leading to direct destruction
of pathogens or marking of pathogens for
destruction by phagocytes
how is active immunity gained
after infection of the pathogen, or after vaccination
what are memory cells
A cell that forms from a lymphocyte as the immune system responds to an infection. It remains in the bloodstream and can recognise pathogens that infect after a first infection. It then differentiates to form antibody-producing lymphocytes that mount a secondary response, (bigger antibody concentration and faster response)