diseases and immunity Flashcards
what is a pathogen?
a disease causing organism
what is a transmissible disease?
a disease in which the pathogen can be passed from one host to another
what is a vector?
an organism that carries a pathogen from one host to another
what is the immune system?
the body’s internal defence system
what are phagocytes?
white blood cells that surround, engulf and digest pathogens
what are lymphocytes?
white blood cells that secrete (produce and release) antibodies
what are antigens?
chemicals on the surfaces of pathogens which are recognised as foreign by the body
what are the 4 types of pathogens?
- viruses
- proctoctists
- fungi
- bacteria
how is a disease transmitted?
- direct contact
- indirect contact
what is direct contact?
transmission through blood and other body fluids
what is indirect contact?
transmission from contaminated
surfaces, food, animals and air
what are the lines of defence in the body against immunity?
- mechanical barriers
- chemical barriers
- cells
what are examples of mechanical barriers?
- collagen in the SKIN to prevent pathogens from entering the body
- hairs in the NOSE to filter out bacteria and foreign particles
what are examples of chemical barriers?
- hcl in the STOMACH that kills ingested pathogens
- mucus in the nose, trachea and bronchi that traps pathogens
- ## tears in the EYES which contain the enzyme lyzozyme which dissolves the walls of bacteria
what are examples of cell barriers?
- lymphocytes: production of antibodies
- phagocytes: engulfing pathogens - phagocytosis
**vaccination
what measures can be used to control the spread of diseases?
- clean water supply
- hygienic food preparation
- good personal hygiene
- waste disposal
- sewage treatment
what is active immunity?
defence against a pathogen by antibody production in the body
describe the process of active immunity?
antibodies that are produced by lymphocytes BIND TO antigens that line the surfaces of the pathogens.
(this either destroys them directly or marks them for phagocytes to locate and ingest them)
some lymphocytes that produce specific antibodies become ______ _____.
memory cells
what is passive immunity?
it is the short-term defence against a pathogen by antibodies acquired by other individuals
give an example of passive immunity
- newborn babies receiving antibodies through the placenta + breast milk
(protecting them from contracting diseases while their own immune system develops.)
how can active immunity be gained through vaccination?
weakened pathogens are put into the body, which stimulates an immune response by lymphocytes that produces antibodies.
memory cells are produced, giving long term immunity
what is the scientific name for cholera?
vibrio cholerae (bacterium)
**WATER BORNE DISEASE
how is cholera transmitted?
cholera secretes toxins that irritate intestinal lining. chloride ions are secreted into the small intestines, which triggers water to move into the gut by OSMOSIS - causing diarrhoea + dehydration.
