Infection and response 1 Flashcards
Types of Disease
What is a pathogen?
A microorganism that causes infectious disease.
What is a communicable disease?
A disease that can be transmitted from one organism to another because it is caused by a microorganism.
How are pathogens spread?
-Direct contact (contaminated surfaces)
-Air (inhalation of airborne droplets)
-Water (contaminated water e.g.cholera)
Name 4 different pathogens
-Bacteria
-Virus
-Protist
-Fungi
What do pathogens do?
-Depend on their host to provide the conditions and nutrients that they need to grow and reproduce
-Make us feel ill
What are viruses?
-not cells
-not living
-still considered organisms
-10000x smaller than animal cells
How do viruses make you unwell?
They reproduce rapidly inside host cells by using the cells’ machinery to produce many copies of themselves.
This causes damage to the host cell, and the cell will usually burst after a time, releasing the viruses which colonise another cell.
It is the cell damage that makes you feel ill
Example of viral diseases
-Measles
-HIV
-TMV
How is measles spread?
Inhalation of airborne droplets (when an infected person coughs or sneezes)
Measles symptoms
-Red-skin rash
-Fever
-(In serious cases pneumonia, blindness, death=why most young children are vaccinated against it)
How can we prevent the spread of measles?
-Vaccination
-Isolate the infected
How is HIV spread?
-Direct sexual contact
-Exchange of bodily fluids e.g. blood when sharing needles
What does HIV stand for?
Human immunodeficiency virus
HIV symptoms
-Mild, flu-like
-Until it develops into late stage HIV, or ‘AIDS
What is AIDS?
A viral infection where the immune system is so weak that the body can no longer fight infection.
What are people with AIDS prone to?
Catching unusual infections
How can we prevent HIV developing into AIDS?
Regular use of antiretroviral drugs, which prevent viruses replicating.
What are bacteria?
-Very small, prokaryotic cells
-Can reproduce rapidly inside your body
Examples of bacterial diseases
-Salmonella
-Gonorrhoea
What does TMV stand for?
Tobacco mosaic virus
What does TMV affect?
It is a widespread plant pathogen affecting many species of plant, e.g. tomatoes.
How is TMV spread?
Direct contact between diseased and healthy plants
(can stay in soil for up to 50 years)
TMV symptoms
-A distinctive mosaic pattern of discolouration on leaves
-Infected areas can’t photosynthesise
-So the plant overall can’t produce enough sugars for proper growth (so stunted growth)
How is Salmonella spread?
-Bacteria ingested in food
-Food prepared in unhygienic conditions
Symptoms of Salmonella
-Fever
-Abdominal cramps
-Vomiting
-Diarrhoea
How can we prevent the spread of Salmonella?
-Vaccinating poultry e.g. chickens
-Cook food thoroughly
How can we prevent the spread of TMV?
-Grow TMV resistant strains of crop
How is Gonorrhoea spread?
-Direct sexual contact (it’s an STD)
Gonorrhoea symptoms?
-Thick yellow/green discharge from the vagina or penis
-Pain when urinating
How can we prevent the spread of Gonorrhoea?
-Use barrier methods of contraception e.g. condoms
-Treat people with antibiotics
How can we treat Gonorrhoea?
-Expensive, rare antibiotics
-Penicillin (first antibiotic) was used but many strains of the bacteria have become resistant to it
How can we treat Salmonella?
-Antibiotics
-Then it usually passes within a week
Examples of fungal diseases
-Rose Black spot
Rose black spot symptoms
-Purple/Black spots on leaves
-Infected leaves often turn yellow and drop off early
-Infected areas can’t photosynthesise
-So the plant overall can’t produce enough sugars for proper growth (so stunted growth)
How is Rose Black spot spread?
by the environment by water or wind
How can we treat Rose Black spot?
-Using fungicides
-Removing/destroying infected leaves
What pathogen causes malaria?
Protists
What might we use gardening manuals or websites to do?
Identify plant diseases
What is a protist?
-Eukaryotes
-Most are unicellular
-Some are parasites
What are parasites?
Organisms that live on or in other organisms causing them damage.
They are often transferred to the organism (host) by a vector when the vector feeds on a healthy animal.
What is a vector?
An organism that transfers a pathogen from one host to another, without getting the disease itself.
Malaria symptoms
-Recurrent episodes of fever
-Can be fatal
How do we prevent the spread of Malaria?
-Stop the vectors, mosquitos, from breeding (e.g. by destroying their breeding grounds)
-Protect people from being bitten by using mosquito nets and insecticides
The malarial life cycle includes the…
mosquito
How do fungi cause disease?
-Some are single - celled
-Others have a body made up of hyphae
-These hyphae can grow and penetrate the surface of human skin and the surface of plants, causing diseases
-The hyphae can produce spores, which can be spread to other plants and animals.
Examples of Protist diseases
Malaria
How can we reduce or prevent the spread of disease?
-Good hygiene routines e.g. washing hands
-Isolating infected individuals
-Vaccination
-Destroying vectors
Which pathogens may reproduce rapidly inside the body?
Bacteria and viruses
How do bacteria make us feel ill?
They produce toxins that damage tissues, making us feel ill.
How do viruses make us feel ill?
They live and reproduce inside cells, causing cell damage and making us feel ill.
How does AIDS develop?
-Unless the HIV virus is successfully treated with antiretroviral drugs, it attacks the body’s immune cells
-If the virus remains inside the body for a prolonged time, the immune system becomes so badly damaged it can no longer deal with other infections, or cancers
-This is known as late stage HIV, or AIDS
What are the symptoms of Salmonella caused by?
The Salmonella bacteria and the toxins they secrete.
How does destroying vectors prevent the spread of disease?
By getting rid of the organisms spreading disease, you can prevent it from being passed on.
How does vaccination prevent the spread of disease?
Vaccinated individuals are less likely to develop the infection and pass it on.
Can lead to herd immunity.
How does isolating individuals prevent the spread of disease?
It prevents them passing on communicable diseases.
Which plant does aspirin originate from?
Willow
