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What are pathogens?
Microorganisms which cause infectious disease
What are four types of pathogen?
Viruses, protists, bacteria, fungi
How can pathogens be spread? (4)
Through air
Through direct contact
Through water (or other ingested substances like food)
By Vectors
Give three words that decsribe diseases that are easily spread
Contagious, Communicable, Infectious
How can the spread of disease can be reduced or prevented? (5)
Hygiene like washing hands
Destroying vectors using insecticides
Destroying insects habitats so they can't breed
Isolating infected individuals
Vaccination
Name three viral diseases
Measles
HIV
TMV
How do viruses make us feel ill?
they live and reproduce inside cells, causing cell damage
What are the symptoms of measles?
Fever and red skin rash
How is measles spread?
when someone inhales droplets of fluid from an infected person's sneeze or cough
How can measles be treated?
Most people are vaccinated against it when they're young
If not vaccinated, the disease cannot be treated (although symptoms may be able to be treated)
What are the symptoms of HIV?
Initially a flu-like illness
Later the body's immune system becomes damage it can no longer deal with other infections or cancers
How is HIV spread?
through sexual contact
By exchanging bodily fluids like drug users sharing needles from infected pregnant mother to baby
HIV can't be treated; how can it be prevented?
Barrier contraception (like condoms), or not sharing needles
How is TMV spread?
by vectors
How can TMV be treated?
Pesticides
Further spread can be stopped by pruning and burning infected leaves
What are the symptoms of TMV (tobacco mosaic virus)?
Mosaic pattern on leaves (parts become discoloured)
Less growth than expected
How do bacteria make us feel ill?
they may produce toxin that damage tissues, making us feel ill
Name two bacterial diseases
• Salmonella
• Gonorrhea
What are the symptoms of salmonella?
• fever
• stomach cramps
• vomiting
• diarrhoea
How is salmonella spread?
By eating food contaminated with salmonella bacteria (foodborne)
How can salmonella be prevented?
Most chickens are vaccinated against it to control the spread. It can also be prevented by cooking chicken hygenically and thoroughly
What are the symptoms of gonorrhea?
• Pain when urinating
• Thick yellow/green discharge from the vagina or penis
How is gonorrhoea spread?
by sexual contact
How is gonorrhoea treated?
Antibiotics
How should gonorrhea be prevented?
Barrier contraception, e.g. condoms
What type of pathogen causes rose black spot?
Fungi
What are the symptoms of rose black spot?
Purple/black spots develop on the leaves of rose plants
The leaves can then turn yellow and drop off
Less growth than expected
How is rose black spot spread?
Through water and wind.
How can rose black spot be treated?
Fungicides
Removing and destroying affected leaves
What type of pathogen causes malaria?
A protist
What are the symptoms of malaria?
Repeating fever episodes
How dangerous is malaria?
It can be fatal
How is malaria spread?
by mosquitos
How can the spread of malaria be reduced?
stopping mosquitoes from breeding
using mosquito nets to avoid being bitten
What are the non-specific defence systems of the human body?
skin
nose
trachea and bronchi
stomach
How do white blood cells help to defend the body against pathogens?
Phagocytosis
Producing antibodies
Producing antitoxins
What do vaccinations involve? (4)
a small amount of a dead/inactive pathogen is injected into the body
the white blood cells produce antibodies that attack the pathogens antigens, even though the pathogen isn't harmful when dead.
the white blood cells memorise the pathogen
if a live pathogen of the same type eneters the body, the memory white blood cells act quickly and multiply to destroy the pathogen, preventing any infection
What do painkillers do?
they relieve pain and help to reduce symptoms of infection, but don't deal with the cause of disease or kill pathogens.
What do antibiotics do?
they help cure bacterial disease by killing infective bacteria in the body
Why can't antibiotics be used to treat viruses?
Viruses reproduce inside body cells. This makes it difficult to develop drugs that just kill the virus and not cells as well.
What does the pharmaceutical industry do?
discover and develop medicinal drugs
When testing drugs, what three things are investigated?
Efficacy (how effective it is)
Toxicity (whether it's harmful)
Dosage (how much, how often)
What is preclinical testing?
tests that are done in a laboratory using cells, tissues and live animals
What are clinical trials?
tests that use healthy volunteers and patients
What is a placebo?
A tablet that does not contain an active drug ingredient
What is phagocytosis?
The receptors on the surface of the WBC detect pathogens
The WBC engulf and destroy the pathogen
What is the production of antioxins?
WBC produce antitoxins
Antitoxins attach to toxins and neutralise them so they don’t harm us
What are antibodies?
WBC produce antibodies
Antibodies attach to the antigen’s on pathogen’s, causing them to clump together
