chapter 10: diseases and immunity Flashcards
(14 cards)
describe a pathogen
a disease causing organism
describe a transmissible disease
a disease in which the pathogen can be passed from one host to another
state ways that a pathogen is transmitted
- direct contact, like with blood or other body fluids
- indirect contact, from contaminated surfaces, foods, animals and air
describe the body defences against a pathogen
mechanical barrier
- skin: prevent pathogens from entering the body
- nose hairs: to prevent pathogens to entering the lungs
chemical barriers
- mucus: traps pathogens for easy removal
- stomach acid: destroys pathogens
cells
- white blood cells: phagocytosis or antibodies
outline ways of controlling the spread of a disease and their importance
- clean water supply: safe drinking water without pathogens like cholera
- hygienic food preparation: help prevent contamination of food with pathogens which could be consumed
- personal hygiene: reduce transmission of pathogens to others
- waste disposal: reduce the presence of pests that can act as vectors for transmissible diseases
- sewage treatement: removal of harmful pathogens before being released into the environment, reduces the risk of contaminated water
describe active immunity
- a defence against a pathogen by antibody production in the body and developing memory cells for a future reponse to the same pathogen
- occurs due to an infection or vaccination
- slow acting and long lasting
describe antibodies
proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes
why is the shape of an antibody important?
- pathogens have antigens on their surface which have complementary shapes to antibodies
- this complementary shape allows the antibodies to bind to the antigen
- allows the antibody to mark/destroy the pathogen
how do vaccines work?
- active immunity activated from dead/weakened pathogens by triggering the immune response
- lymphocytes create antibodies to either destroy or mark the pathogen
- the antibodies bind to the antigens of the pathogen as due to the complementary shape
- memory cells created for long-term immunity
- herd immunity created by vaccinating a large population, disrupts person to person transmission
describe passive immunity
- short term defence against a pathogen by antibodies acquired from another individual
how can infants gain passive immunity?
- breastfeeding
- diffusion of antibodies across placenta
- they only get passive immunity against the specific pathogens for which the mother has antibodies for
- very important for infants to get passive immunity so they can fight off infections until they are older and stronger and when their immune system is more responsive
what is an antitoxin?
a protein that neutralises the toxins produced by bacteria
describe the differences between active and passive immunity
- active is long lasting
- active is slow acting
- active triggers the immune response
- antibodies and memory cells are created for active
describe cholera
- a disease caused by a bacterium which is transmitted in contaminated water
- produces toxins which causes the secretion of chloride ions into the small intestine lumen, descreasing the water potential of the lumen
- water moves by osmosis into the small intestine
- diarrhoea, dehydration, loss of ions from blood
