Download File - Sydney russell school e

B1 L1
Learning Objective
To be able to explain what a pathogne is and how it is spead and how to
prevent its spread with hygiene
Starter activity: What is average speed of a human sneeze? And how far does it
travel?
Can travel as fast as 700mph
Can spread up to 2 metres
away
Success Criteria
At the end of this lesson it will be:
Best
Better
Good
Able to explain what causes infectious
diseases and how they are spread
Able to explain how pathogens are combatted
Able to state what a pathogen is
Microorganisms
• Microorganisms are tiny living things that can only be seen
using a microscope.
The microorganisms that cause disease are types of Pathogen
of which the main types are:
Bacteria
Viruses
Louis Pasteur studied
microorganisms, proved these
‘germs’ in the air carried
infection and disease.
Learning objective check
Good
Able to state what a pathogen is
How can we prevent pathogens?
Joseph Lister also studied
microorganisms, he developed a
special soap (carbolic soap) which he
insisted all medical instruments,
dressings and surgeons should be
cleaned with it before any operation.
More of Lister’s patients stayed healthy
than those of other surgeons.
Chemicals that are used to clean wounds or get rid of
sores, such as nappy rash are called antiseptics.
Chemicals that are used to clean work surfaces and other
places where pathogens might be found are called
disinfectants.
How were pathogens combatted?
Ignaz semmelweiss wondered why so many women died of childbed fever soon after
giving birth.
He also noticed that the student doctors carrying out their work on dead bodies did
not wash their hands before delivering a baby.
Semmelweiss showed that
Keeping things cleans stops the spread of pathogens, this is called HYGEINE.
Hygiene is about keeping things clean to reduce the risk of transmitting
disease.
Washing removes the dirt and
grease that pathogens stick to and
use as a source of energy to
multiply.
Learning objective check
Better
Able to explain how pathogens are combatted
How do pathogens spread?
• Bacteria and viruses can pass from one person to
another. This is how some diseases spread and affect
many people.
• You can become infected by pathogens in the air you
breathe, the food you eat and by touching someone.
Learning objective check
Better
Able to explain how pathogens are combatted
2
(2)
(3)
(2)
Pass to peer for
Peer marking
Plenary
• Discuss and Identify 3 important points from
this lesson which you will need to revise
How are pathogens spread?
What is a pathogen?
State the 2 main types of pathogen?
.
Outline the experiments carried out by Ignaz Semmelweiss and
explain the contribution of these to modern medicine.
What is Hygiene?
What precautions did joseph lister take to prevent the
spread of pathogen
What are antiseptics used for?
what are disinfectants used for?
What is a pathogen?
Microoganism that causes disease.
Explain how the following make you ill:
Bacteria Reproduce rapidly and
produce toxins
Viruses reproduce inside e cells and
damage them
Explain how white blood cells protect
you from disease.
• Ingest pathogens (phagocytosis)
• Produce antibodies – destroy
specific bacteria or viruses
• Produce antitoxins – neutralise
toxins released by pathogens
Explain how antibiotic resistance
develops in bacteria.
Bacteria mutate by chance
Bacteria with mutation not killed by
antibiotic
These cells can survive to reproduce
And pass the gene for resistance to
their offspring – population of
resistant bacteria increases
What is a sterile culture.
Culture of only one type of microorganism.
Give 2 reasons it is important to keep
cultures sterile. .
Other microbes would use up food
resources
Other microbes may produce dangerous
toxins
Explain how vaccination works:
•Small amount of dead or inactive pathogen injected
•Stimulates memory cells to form
•Next time pathogen enters body white blood cells make
antibodies faster and in greater numbers
What 3 diseases
does MMR vaccine
protect from?
Measles
Mumps
Rubella
Why is overuse of antibiotics a problem?
Selects for antibiotic resistant bacteria to survive.
These are hard to treat.
How can we reduce this problem?
Do not use antibiotics for minor infections
Reduce use in agriculture
What is a mutation?
Change in a gene
Why is mutatioin in pathogens
problematic?
Creates new strains that
people have no immunity to or
are resistant to antibiotics
What temperature should
we incubate cultures at in
school and why? How does
this compare to industry?
25oC – to prevent growth of
human pathogens.
Industry higher – faster
growth rate.
How can the following drugs be
used to treat disease?
Painkillers relieve symptoms (don’t
kill pathogen)
Antibiotics Kill bacteria
Why can’t antibiotics be used
to kill viruses?
Viruses replicate inside human
cells so the antibiotic can’t
reach them or would kill the
human cell.
Why are antibiotics used in
farming?
Help animals gain weight – less
energy spent overcoming
infection
Increase profits – prevent
spread of infection
List 4 precautions you must take when carrying out
aseptic technique to grow a sterile cuture
1. Sterilise petri dish and culture medium before use
2. Sterilise innoculating loop by passing through a flame
3. Tape lid to prevent contamination from air
4. Work near a flame
Outline the experiments carried out by Ignaz
Semmelweiss and explain the contribution of these to
modern medicine.
Noted death rates on maternity wards much lower when
midwives delivered compared to doctors - realised
doctors were transferring disease from surgery
Encouraged use of chloride of lime to wash hands and kill
bacteria - Death rates drastically fell
Shows importance of handwashing to prevent spread of
infection