Communicable Diseases Flashcards
What are
pathogens
Microorganisms that cause illness and
diseases
Pathogen
examples
Viruses, bacteria, protists and fungi
How bacteria make
us ill
They release toxins into our body
How viruses make
us ill
They enter our body cells, multiply inside
and then destroy/damage the body cells
How we defend
ourselves against
pathogens
Produce antitoxins to neutralise the toxins
Produce antibodies which attach to the
antigens on the surface of pathogens and
slow them down
White blood cells engulf and ingest
pathogens
What important
discovery did
Semmelweis
make?
Handwashing prevents the spread of
diseases. He insisted that doctors
washed their hands before examining
patients. This practice drastically reduced
deaths in hospitals.
How do you treat a
bacterial infection?
With antibiotics.
How do you treat
viral infections?
With antivirals which work on viruses
inside cells. This could damage the cells.
Other medicines can alleviate the
symptoms (e.g. painkillers).
Why should we
avoid the overuse
of antibiotics?
To prevent the development of
superbugs. Due to mutations, some
pathogens are resistant to the antibiotic.
These pathogens survive and multiply. An
example of an antibiotic resistant
pathogen is MRSA.
MMR vaccinates
against…
Mumps, measles and rubella
How to grow
bacterial cultures in
the lab
Sterilise the agar plate
Sterilise the petri dish
Sterilise the inoculation loop by holding it
into a roaring Bunsen Burner flame.
Transfer bacteria onto agar plate using
sterile loop.
Place a lid on the petri dish to prevent
microorganisms from the air from entering.
Secure the lid loosely with Sellotape.
Make sure it is not sealed completely.
Without oxygen entering, very harmful
microorganisms would develop inside the
petri dish.
At what
temperature is the
petri dish
incubated?
37oC in industry
25oC in schools to prevent harmful
bacteria from growing.
How does a
vaccination work?
A weak/dead pathogen is injected. The body
produces antibodies.
When the live pathogen enters the body, the
body remembers to the specific antibodies
needed and produces it more quickly.
What is a
communicable
disease?
An infectious disease.
How do pathogens
spread?
Air, water, touch, contaminated food,
animal to animal.
What is a vector?
An animal that spreads a communicable disease.
Give examples of
viral diseases
Measles – fever, red skin rash. Can be
fatal. Passed on through air when people
sneeze or cough.
HIV – causes flu-like illness. Spread by
sexual contact or exchange of body fluids
and blood.
Give examples of
bacterial diseases
Salmonella food poisoning – ingested in
food. Fever, cramps, vomiting, diarrhoea.
Gonorrhoea – STD; thick yellow or green
discharge from vagina or penis and pain
when urinating. Prevented by use of
condom.
Give an example of
a fungal disease
Athletes foot – causes itching, flaking and
blistering.
Give an example of
a protist disease
Malaria – causes recurrent periods of
fever and can be fatal. Controlled by
preventing the vector, the mosquito, from
breeding and by using mosquito nets to
prevent being bitten.
What is the
human’s first line of
defence against
pathogens?
- Skin – forms outer barrier and
produces antimicrobial compounds
which kill some pathogens. - Lysozymes in tears and saliva – an
antibacterial enzyme which breaks
down the cell walls of bacteria. Tears
also contain antibodies. - Hairs and cilia – these are found in
your nose, trachea, lungs, intestines.
Together with mucus they act as a
filter. The pathogens get stuck in the
mucus and wafted out of the body by
the cilia. - Stomach acid – pH low enough for
many pathogens to not survive.
What is the second
line of defence
against pathogens?
Phagocytes – white blood cells that engulf,
ingest and digest pathogens. Phagocyte
binds to pathogen, pathogen is absorbed
into the vacuole where enzymes break
down the pathogen. This is called
phagocytosis.
What is the third
line of defence
against pathogens?
Lymphocytes – recognise antigens and
produce antibodies that are specific to
antigens. Antibodies help clump together
pathogens so they can be destroyed by
phagocytes.
Antitoxins – Lymphocytes produce antitoxins
to neutralise the action of the toxins released
by the pathogens.
