4.1- Communicable diseases, prevention and the immune system Flashcards
What is a communicable disease?
A disease which can be spread between organisms
What are three diseases which are caused by bacterium?
Tuberculosis
Ring rot
Bacterial meningitis
What are three diseases which are caused by viruses?
HIV
Influenza
Tobacco mosaic virus
What are three diseases caused by fungus?
Black sigatoka
Ringworm
Athlete’s foot
What are two diseases caused by protoctists?
Potato / tomato late blight
Malaria
What is a pathogen?
An organism that causes disease
What are the four main types of pathogens?
Bacteria
Viruses
Fungi
Protoctista
What does tuberculosis affect?
Bacterium affects Animals, typically humans and cattle
What does bacterial meningitis affect?
Bacteria affects humans
What does ring rot typically affect?
Bacterium affect potatoes and tomatoes
What does HIV typically affect?
The virus affects humans
What does influenza typically affect?
The virus infect animals, including humans
What does tobacco mosaic virus typically affect?
The virus affect plants
What does black sigatoka typically affect?
The fungus affect banana plants
What does ringworm typically affect?
The fungus affects cattle
What does athlete’s foot typically affect?
The fungus affects humans
What does potato/tomato late blight affect?
The Protoctist effect potatoes and tomatoes
What does malaria typically affect?
The protoctist affect animals, including humans
What is direct transmission?
When a disease is transmitted directly from one organism to another.
What three ways can a communicable disease be transmitted directly?
Droplet infection
Sexual intercourse
Touching an infected organism
What is indirect transmission?
When a disease is transmitted from one organism to another via an intermediate.
What are four examples of intermediates in indirect transmission?
Air
Water
Food
Another organism (known as a vector)
What are two examples of diseases that can be transmitted directly?
HIV can be transmitted by sexual intercourse
Athlete’s foot can be spread via touch
What are two examples of diseases that can be spread by indirect transmission?
Potato / tomato late blight is spread when spores are carried between plants
Malaria is spread between humans by mosquitoes which act as vectors
What three factors affect the transmission of communicable diseases?
Living conditions, climate, social factors
Give an example of how living conditions affect the spread of disease.
In overcrowded living conditions, Tuberculosis can spread easier as people will have more contact with each other
Give an example of how climate can affect the spread of disease.
- Potato/tomato late blight is common during wet summers because spores need water to spread
- Malaria is common in hot countries as these are ideal conditions for mosquitos to breed
How can social factors affect the spread of disease?
Good healthcare and good education can help prevent the spread of HIV by educating people.
How does tuberculosis cause harm?
It affects many parts of the body, killing cells and tissues
How does bacterial meningitis cause harm?
It infects the membrane that surrounds the brain and the spinal cord (meninges)
How does ring rot cause harm?
It causes a ring of decay in the tissue of a potato tuber or tomato, accompanied by a leaf wilting
How does HIV cause harm?
It attacks cells in the immune system and compromises the immune response
How does influenza cause harm?
It attacks the respiratory system and causes muscle pains and headaches
How does tobacco mosaic virus cause harm?
It causes the discolouration of leaves and stops a plant photosynthesising
How does Black sigatoka cause harm?
It causes Leaf spots on banana plant reducing yield
How does potato/tomato late blight cause harm?
It affect leaves and potato tubers
How does ringworm cause harm?
The growth of the fungus in the skin causes a rash
How does athlete’s foot cause harm?
There is growth under the skin of feet, which can cause discomfort
How does malaria cause harm?
Parasites can cause headache and fever and made progress to coma and death
How can plant pathogens be transmitted?
Pathogens enter the roots from the soil
Pathogens can enter fruit seeds and be spread when these spread
Insect attacks can infect pathogens
How can diseases be transmitted by animals directly?
Direct physical contact
Oral transmission
Droplets
Transmission by spores which can be carried in the air
How does skin prevent infection?
It acts as a physical barrier, blocking pathogens from entering the body
It also produces antimicrobial chemicals that inhibit the growth of pathogens
How do mucous membranes prevent infection?
Mucous membranes protect body openings that are exposed to the environment
They secrete mucus which traps pathogens and contain antimicrobial enzymes
How does blood clotting prevent infection?
Blood clots plug wounds to prevent pathogen entry and blood loss
How does inflammation prevent infection?
When tissues are damaged, the permeability of blood vessels increase and they swell which helps isolate any pathogens in the damaged area
Vasodilation also brings white blood cells to the area to fight off any pathogens
How does wound repair prevent infection in animals?
The skin is able to repair itself and we form a barrier against pathogen entry
How do expulsive reflexes prevent pathogen entry?
Coughing and sneezing are attempts to expel foreign objects when the mucus membranes or respiratory tracts are irritated
How does the waxy cuticle of plants defend against pathogens?
The waxy cuticle provides of physical barrier and stops water collecting on The Leaf which could reduce the risk of infection
What are the three physical defences for plants have against pathogens?
Waxy cuticle
Cell walls
Callose
How does cell walls defend against pathogens in plants?
They form a physical barrier against pathogens that make it past the waxy cuticle
How does callose defend against pathogens in plants?
Callose gets deposited between plant cell walls and plasma membranes (and plasmodeselata) during times of stress
Callose deposition makes it harder for pathogens to enter cells and limit the spread of disease
What are the two chemical defences the plants use to defend against pathogens?
They produce antimicrobial chemicals
They produce chemicals toxic to insects
How the antimicrobial chemicals defend against pathogens in plants?
Saponins destroy the cell membrane of fungi and other pathogen
Phytoalexins inhibit the growth of fungi and other pathogens
How does plant secreting chemicals toxic to insects, defend against pathogens?
It reduces the amount of insect feeding on plants and the risk of infection by insect vectors
What are antigens?
Molecules found on the surface of cells.
When a pathogen invades the body, the antigens are identified as foreign which activates the immune response
What is the first stage in the immune response?
Phagocytes engulf pathogens (somutimes using opsonins)
The pathogen is now contained in a phagosome where digestive enzymes break down the pathogen
The phagocyte then presents the pathogens antigens
What is the second stage of the immune response?
Phagocytes activate t lymphocytes which bind to the complementary antigens by clonal selection
The t-lymphocyte then undergoes Clonal expansion
What are the three different types of T lymphocytes?
T helper cells
T killer cells
T regulatory cells
What is the third stage of the immune response?
T lymphocytes activate B lymphocytes, which divide into plasma cells
What is the fourth stage of the immune response?
Plasma cells make more antibodies to a specific antigen so more antigen-antibody complexes of stormed and the pathogen is destroyed
