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

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

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

Exam question 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

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?

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.