Chapter 10: Diesease And Immunity Flashcards
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
How is pathogen transmitted?
- by direct contact, including through blood and other body fluids
- indirectly, including from contaminated surfaces, food, animals and air
Use of Skin in body defense
The skin prevents infection from pathogens. If it is cut or grazed, it immediately begins to heal itself, often by forming a scab.
Use of a nose in body defense
The nose has internal hairs, which act as a physical barrier to infection.
Use of a mucus in body defense
The mucus is produced by goblet cells and traps bacteria, dust, particles; The cilia beat; And push the mucus away from the lungs towards the throat.
Use of stomach acid in body defense
It contains hydrochloric acid, it is strong enough to kill any pathogens that have been caught in mucus in the airways or consumed in food or water.
Use of white blood cells in body defense
White blood cells attack pathogens.
Lymphocytes
They recognise proteins on the surface of pathogens called antigens. Lymphocytes detect that both the proteins and pathogens are foreign and produce
antibodies.
Phagocytes
They surround pathogens in the blood, bind to them and engulf them.
Describe active immunity
defence against a pathogen by antibody production in the body
What do pathogens have
each pathogen has its own antigens, which have specific shapes
Describe antibodies
proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes
How do antibodies bind to the varying shape of antigens?
specific antibodies have complementary shapes which fit specific antigens
How is active immunity gained?
after an infection by a pathogen or by vaccination
Process of vaccination
(a) weakened pathogens or their antigens are put into the body
(b) the antigens stimulate an immune response by lymphocytes which produce antibodies
(c) memory cells are produced that give long-term immunity
Explain the role of vaccination in controlling the spread of diseases
White blood cells make correct antibodies, so that if in future the real microorganisms get into the blood, the antibody is already or very quickly made by the body. This prevents spread of disease.
What is passive immunity?
is a short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk
importance of breast-feeding for the development of passive immunity in infants
When a mother breast-feeds her baby, the milk contains some of the mother’s white blood cells, which produce antibodies -provide baby with protection against infection at a vulnerable time.
Are memory cells developed in passive immunity
Memory cells are not produced
Hygienic factors that prevent spread of disease
(a) a clean water supply
(b) hygienic food preparation- all milk should be pasteurised, meat thoroughly cooked and at bottom of fridge.
(c) good personal hygiene- Must wash hands before handling food and after going to toilet
(d) waste disposal- should be stored in dustbins or garbage cans. Then get rid off by burning or burying deep
(e) sewage treatment- If disease bacteria get into water supplies used for drinking, hundreds of people can become infected.
Describe cholera
a disease caused by a bacterium which is transmitted in contaminated water
What does cholera do?
cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration and loss of ions from the blood
