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 in which pathogen is transmitted by
- Direct contact: Directly from body fluids such as blood or semen
- Indirect contact: Pathogen is carried by an intermediate medium or vector such as from contaminated surfaces, food, animals and air
Describe the body defences, limited to: skin, hairs in the nose, mucus, stomach acid and white blood cells
- Skin: Prevents infections from pathogens
- Hair in the nose: Difficult for pathogens to get past. Prevents it from being inhaled into the lungs
- Mucus: Traps pathogens and removes it
- Stomach acid: Kills pathogens that have been swallowed, or consumed
- Phagocytosis: Engulfs and digests pathogenic cells
- Producing antibodies: Undergoes agglutination and signals to other cells, to destroy
Explain the importance of the following in controlling the spread of disease:
(a) a clean water supply
(b) hygienic food preparation
(c) good personal hygiene
(d) waste disposal
(e) sewage treatment
- Clean water supply: Ensures water is free of pathogens, preventing waterborne diseases
- Hygienic food preparation: Prevents contamination of food with harmful bacteria and fungi
- Good personal hygiene: Reduces transmission of diseases
- Waste disposal: Reduce the prevalence of pests, and flies that can act as vectors for transmissible diseases
- Sewage treatment: Removes harmful pathogens from waste before releasing into the environment. Reducing the risk of diseases spreading in contaminated water
Describe active immunity
Defence against a pathogen by antibody production in the body
Describe antibodies
Proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes (an immune response)
Explain how active immunity is gained
- The initial response: Of lymphocytes encountering with pathogens takes a few days (person’s sick during)
- Lymphocytes give rise to memory cells: That retain instructions for making specific antibodies (after the initial encounter with a pathogen)
- Immunity to certain diseases: When reinfected by the same type of pathogens, antibodies are made very quickly in greater quantities (destroying pathogens before they multiply)
Outline the process of vaccination
- Body is introduced: To dead or altered form of disease-causing pathogens, which contain specific antigens
- Pathogens stimulate an immune response: Causing lymphocytes to produce complementary antibodies for the antigens
- Memory cells are produced: As antibodies attach to antigens on pathogenic cells. Henceforth, when lymphocytes encounter a live pathogen, they’ll respond very quickly
Explain the role of vaccination in controlling the spread of diseases
- A large enough percentage of vaccinated people in a population, protects the entire population. As only few pathogens are able to breed in unvaccinated people
- If the number of vaccinated people against a specific disease drops, the population is at risk of mass infection. Henceforth, coming across infected and contagious people are likely; increasing the number of infections and deaths by the disease
Explain passive immunity
A short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk
Explain the importance of breast-feeding for the development of passive immunity in infants
Provides support for infants to fight off infections from young until they’re older, As the immune system becomes more responsive
Describe cholera
A disease caused by a bacterium which is transmitted in contaminated water
Explain the process of chloera
- Attaches: To the wall of small intestine, producing a toxin
- Stimulation: Of the cell’s lining by the toxin. Releasing chloride ions from inside the epithelial cells of the small intestine, to the lumen of the intestine
- Osmotic Movement: Occurs as chloride ions accumulate in the lumen, lowering water potential. W.P is lower than the cell’s lining, water moves out of the cells into the intestine
- Consequences: Quantities of water are lost from the body in water faeces. Resulting to diarrhoea, little chloride ions and water (dehydration) in the blood
