1. L3 - Pathogens Can travel as fast as 700mph
B1 L1
L3 - Pathogens
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

2. Best Better Good Success Criteria Able to state what a pathogen is
At the end of this lesson it will be:
Able to explain what causes infectious diseases and how they are spread
Best
Able to explain how pathogens are combatted
Better
Able to state what a pathogen is
Good

3. 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.

4. Learning objective check
Good
Able to state what a pathogen is

5. 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.

6. 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.

7. Learning objective check
Better
Able to explain how pathogens are combatted

8. 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.

9. Learning objective check
Better
Able to explain how pathogens are combatted

10. Exam question 2
(2)

11. (3)
(2)

12. Pass to peer for Peer marking

13. Plenary
Discuss and Identify 3 important points from this lesson which you will need to revise

14. 1.1 Pathogens How are pathogens spread? What is Hygiene?
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?

15. 1.1 Microbes and Disease What is a pathogen?
Microoganism that causes disease.
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
How can the following drugs be used to treat disease?
Painkillers relieve symptoms (don’t kill pathogen)
Antibiotics Kill bacteria
Explain how the following make you ill:
Bacteria Reproduce rapidly and produce toxins
Viruses reproduce inside e cells and damage them
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.
What 3 diseases does MMR vaccine protect from?
Measles
Mumps
Rubella
1.1 Microbes and
Disease
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
Why are antibiotics used in farming?
Help animals gain weight – less energy spent overcoming infection
Increase profits – prevent spread of infection
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
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 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
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
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
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.