Infection and Response Flashcards
Define pathogens
microorganisms that enter the body and cause disease
Define health
the state of physical and mental well-being
What is a communicable disease?
a disease that can be transmitted from one organism to another
What are the four types of pathogens?
- Bacteria
- Viruses
- Protists
- Fungi
How does bacteria make us ill?
They reproduce rapidly and produce toxins that damage your cells and tissues
How do viruses make us ill?
They reproduce rapidly using a cell’s machinery until it bursts, releasing the new viruses
The cell damage makes us feel ill
How do protists cause disease?
some protists are parasites and live on or inside an organism to cause damage
they often travel via a vector
How does fungi cause disease?
Some fungi have hyphae
The hyphae penetrates the human skin / surface of plants and cause diseases
hyphae - fungi’s body / thread-like structures
What pathogen produces toxins?
bacteria
What pathogen often uses a vector?
protists
What 5 ways can pathogens be spread? + an example
- Water - cholera
- Air - influenza/common cold
- Direct contact - athlete’s foot
- Contaminated food - salmonella
- Vector - malaria
What ways can the spread of diseases be prevented?
- Being hygienic (e.g. washing hands)
- Destroying vectors (e.g. using intecticides)
- Isolating infected individuals
- Vaccination
- Reducing direct contact (e.g. using condoms)
Give three examples of a viral disease
- Measles
- HIV(Human Immunodeficiency Virus)
- TMV (Tobacco mosaic virus)
Can viruses be killed by antibiotics?
No
What are the symptoms of measles?
- red skin rash
- fever (a high temperature)
How is measles spread?
It is airborne.
It can spread through droplets in the air after sneezing which can be inhaled.
What can measles lead to?
- Lung damage (pneumonia)
- Brain infection (encephalitis)
What is used to prevent measles?
People are vaccinated against it when they’re young
What are the symptoms of HIV?
- flu-like symptoms (fever, cough, sore throat)
after this there are usually no other symptoms
How is HIV spread?
Exchanging bodily fluids:
* Sexual contact
* Sharing needles
What does HIV lead to?
It attacks the immune system cells - damaging it
This means it can’t cope with other infections or cancers
How is HIV treated?
It cannot be cured.
But you can take antiretrovial drugs to stop the virus from replicating in their bodies
What does TMV do to plants?
(plant infection)
It causes leaves to discolour in a mosaic pattern
What does the TMV discoloured leaves lead to?
It causes the rate of photosynthesis to reduce
causing growth to reduce
Give two examples of a bacterial disease
- Salmonella
- Gonorrhoea
Can bacterial diseases be killed by antibiotics?
Yes
What are the symptoms of salmonella?
- fever
- stomach cramps
- vomiting
- diarrhoea
How does salmonella spread?
by eating food that is contaminted with salmonella bacteria
chicken that had salmonella or food prepared in unhygienic conditions
How does the UK control the salmonella?
In the UK, poultry is vaccinated against salmonella
poultry - chicken/turkey
What are the symptoms of gonorrhoea?
- pain when urinating
- thick yellow / green discharge from vagina / penis
How does gonorrhoea spread?
Through sexual contact
It’s an STI
How was gonorrhoea treated before? Why doesn’t it work now?
With penicillin
It doesn’t work because strains of the bacteria have become resistant to it
How is gonorrhoea treated now?
/ control the spread
- treated with antibiotics
- use barrier methods of contraception (condom)
Give an example of a disease caused by a protist
Malaria
What are the symptoms of malaria?
- repeated episodes of fever
How is malaria spread?
Via a vector (mosquito)
The mosquito picks up malaria from infected animals and infects others by inserting it into the blood vessels
How can you reduce the spread of malaria?
- stopping mosquitos from breeding - draining areas of still water
- kill them with insecticides
- use mosquito nets to protect yourself
Give two examples of a fungal disease
- Rose black spot
- Athlete’s foot
What does rose black spot do to plants?
causes leaves to develop purple or black spots
The leaves turn yellow and fall off
What do infected rose black spot leaves lead to?
It causes rate of photosynthesis to fall
This causes rate of growth to decrease
How is rose black spot spread?
- water
- wind
How can you treat rose black spot?
- remove infected leaves (and destroy them)
- spray with fungicides
How is your nose adapted to defend against entry of pathogens?
- hairs
- mucus
to trap particles
How is the trachea and bronchi adapted to defend against entry of pathogens?
- secrete mucus
- lined with cilia which waft the mucus to the back of the throat to be swallowed
How does the stomach protect against the entry of pathogens?
Produced hydrochlauric acid which kills pathogens
How does your skin defend against pathogens?
acts as a barrier with dead skin cells and secretes sebum
What does the immune system do?
- protect us against pathogens and any toxins they produce
- to protect against the same pathogen in the future
prevent disease
What are the three ways white blood cells can attack pathogens?
- Phagocytosis
- Producing antibodies
- Producing antitoxins
What is phagocytosis ?
White blood cells (phagocytes) engulf foreign cells and digest them.
(ingest them)
What are antigens?
unique molecules on the surface of a pathogen
(this is just for understanding)
What are antibodies?
proteins produced by lymphocytes (white blood cells) that recognise pathogens ( and clump them together so they can be easily engulfed ) ( this triggers them to be destroyed )
What happens if a pathogen infects a body for the second time?
a pathogen with antigens
The lymphocytes recognise the pathogen and produces more antibodies, more quickly
What are antibodies specific to?
the type of antigen they attack
What do white blood cells produce to fight against toxins?
Anti-toxins
They bind with and neutralise the toxins
How do vaccines work?
- They inject dead / inactive pathogens
- The white blood cells produce antibodies
- If the same pathogen enters the body later, white blood cells will recognise it
What are the pros of vaccines?
- the help control communicable diseases that were once common (e.g. polio and smallpox)
- epidemics can be prevented if lots of people are vaccinated
epidemics - big outbreaks of disease
What are the cons of vaccines?
- don’t always work / give immunity
- bad reactions e.g. swelling, seizures (although rare)
What was the first antibiotic?
Penicillin
What do painkillers do?
/ not do
They relieve pain but don’t kill pathogens
They just help reduce symptoms.
What do antibiotics do?
They kill infective bacteria without killing body cells.
Different antibiotics kill different bacteria
Which type of pathogen can antibiotics be used to kill?
Bacteria
not viruses !!
What is antibiotic resistance?
When bacteria mutates so it cannot be killed by the antibiotic and so becomes resistant
It is caused by the over use of antibiotics
Why is it important to finish a whole course of antibiotics?
So all bacteria is killed and no resistant strains are made
Where is aspirin found?
In the bark of a willow tree
painkiller
Where is digitalis found?
Foxgloves
used for heart conditions
What is preclinical testing?
testing on human cells and tissues and then live animals
What is clinical testing?
Testing on human volunteers
What happens in clinical testing?
not including placebo groups
- Low dose given healthy volunteers to check the drug has no harmful side effects
- Drug is tested on people with the illness and dosage increases until optimal dose is found (most effective + few side effects)
How are placebos used in testing drugs?
There’s a placebo group and a new drug group
This is to eliminate the placebo effect
the volunteers don’t know which group they’re in
What are double-blind trials?
neither the patient nor the doctor know which group is which
Why are double-blind trials used?
To stop bias and so that the doctors monitoring aren’t subconsiously influenced
Why do scientists use peer review?
(other scientists check the work is valid)
To prevent false claims
