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Unit B2Unit B2

Keeping Keeping HealthyHealthy

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Lesson 1: Lesson 1: MicrobesMicrobes

Lesson objectives:

1)To be able to list at least 4 ways through which microbes can enter

our bodies

2) To be able to list 4 natural barriers the human body has to defend against microbes

3) To be able to state why microbes get past our first line of defence

Unit B2: Unit B2: What are What are microbes?microbes?

STARTER

Try and define a microbe in your own words.

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MicrobesMicrobesMicrobes are micro organisms that are too

small to be seen. A pathogen is a microbe that can cause diseases if it enters

the body:

…or other natural openings…

They can be breathed in through the mouth or nose

They can enter through cuts or bites in the skin or just by touching something

They can be ingested (eaten) through the mouth

19/04/23Microbes: our defence against Microbes: our defence against themthem

Our bodies have many defence mechanisms against invading microbes:

If our skin is cut platelets seal the wound by clotting

The breathing organs produce mucus to cover the lining of these organs and trap the microbes

The skin acts as a barrier

Stomach produces stomach acid

Tears contain an enzyme that kills bacteria

How quickly do microbes How quickly do microbes grow during our school ?grow during our school ?

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How many antibacterial or How many antibacterial or antimicrobial products antimicrobial products

can you think of?can you think of?

19/04/23Antibacterial products we see Antibacterial products we see on T.V.on T.V.

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Agar petri dishAgar petri dish

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AimAim: : To investigate the effect of antimicrobial products

• Equipment:

• Method: - what did you do?– Dependent variable (the factor you will record/measure)– Independent variable (the factor you will change)– Control (what factors will you keep the same?)Draw diagram of how you made up the petri dish

• Results: Draw a results table to record what you see next lesson.

• Conclusion:

• Evaluation: Was it a fair test? Did you get any strange results and why?

19/04/23Additional points for your Additional points for your conclusion…..conclusion…..

C/B Grade• Explain how dilution affects the activity of

antibacterial chemicals and why.

A Grade• Explain how do you think the concentration

of cosmetic products and medicines is calculated to give maximum benefit from the minimum amount of chemical.

19/04/23Additional points for your Additional points for your conclusion…..conclusion…..

C/B Grade• How dilution affects the activity of antimicrobial

chemicals and why.

A Grade• How do you think the concentration or dosage in

cosmetic products and medicines is calculated to give benefit from the minimum amount of chemical

(if a range of bacterial species has been used)

A* Grade• Do you think antimicrobial chemicals are more effective

against some microbes than others? What other factors could change the effectiveness of these chemicals?

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Title: Title: What are the different What are the different ways in which microbes spread ways in which microbes spread

& how fast?& how fast?• What are the different ways through which

microbes can spread?–Water–Air–Food–Touch–Animals–SexWAFTA’S!

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What are the different What are the different ways in which pathogens ways in which pathogens

spread?spread?

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How fast can bacteria grow How fast can bacteria grow in a school day?in a school day?

• Worksheet

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If bacteria can grow that fast….then why

isn't the earth covered with bacteria?!?!!

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The main reason may be that conditions are rarely

optimum!

Bacteria also can’t “hunt” for food…so existing nutrients

eventually run out.

19/04/23Graph showing how bacteria Graph showing how bacteria grow in a sealed containergrow in a sealed container

• Steady phase – growth of new bacteria equals death of old bacteria

• Fastest increase in growth – bacteria divide every 20 mins.

• More bacteria die than are made.

• Growth gets going.

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‘‘Outbreak’ scenarioOutbreak’ scenarioYou have been notified of an

unidentified microbe.

• How will you find out how it spreads?

• How will you find out how fast it spreads?

19/04/23DiseaseDiseaseA disease is any condition where the body isn’t working as it should. This could be caused by a malfunction in the body (as with diabetes), or it could be caused by the two types of MICROBE:

VirusesBacteria

•1/1000th mm big

•Living cells (some are harmless)

•Grow very quickly

•Affected by antibiotics

•Examples: food poisoning, tetanus, sore throats

•1/1,000,000th mm big

•Genetic info inside a protein coat

•Not affected by antibiotics

•Release poisons

•Examples: colds, flu, polio, chicken pox

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FungiFungiFungi are another form of microbe. There are many different varieties ranging from bread mould to mushrooms.

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How does our body help How does our body help to keep us to fight to keep us to fight

pathogens?pathogens?

19/04/23Title: Title: What happens What happens when microbes enter when microbes enter

our body?our body?

What’s the name of the cells that defend our bodies against

pathogens?

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Today’s lessonToday’s lesson• To be able to describe, in

detailed steps, how our immune system fights microbes

• To be able to explain how our immune system works when a microbe attacks for the 2nd time.

• Produce a basic storyboard with steps on how our defence system works.(C/B grade)

• Write own key words

• Annotated diagrams on storyboard using the correct scientific terms (B/A grade)

19/04/23Pathogens usually have Pathogens usually have ‘antigens’‘antigens’ on their surface on their surface which is recognised by our which is recognised by our

immune systemimmune system

Antigens cause our immune system to produce ‘‘antibodies’antibodies’

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Fighting diseaseFighting diseaseIf microbes do enter our body they need to be neutralised or killed. This is done by WHITE BLOOD CELLS:

White blood cells do 3 things:

1) They produce antibodies to neutralise the microbe

2) They eat the microbe

3) They produce antitoxins to neutralise the poisons produced by microbes

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The type of WBCthat engulf the pathogen are called phagocytes

The parts that extend to engulf the pathogen is called a pseudopod and are like ‘false legs’

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phagocyte phagocyte

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Your taskYour task

• Create a storyboard which describes how our WBC’s fight pathogens.

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Producing antibodiesProducing antibodies

Step 1: The white blood cell “sees” the antigen (microbe)

Step 2: The cell produces antibodies to “fit” the antigen

Step 3: The antibodies fit onto the antigens and cause them to “clump”

Step 4: The antigens are “eaten” by the white blood cells

You’re going down

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How do our bodies make How do our bodies make us ‘immune’ after we get us ‘immune’ after we get

a disease just once?a disease just once?

19/04/23Re-cap: Re-cap: antigen/antibody antigen/antibody actionaction

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How would you draw a How would you draw a graph of what happens to graph of what happens to

antibody production?antibody production?

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GraphGraph1. How no. of antibodies change during the

first 20 days of exposure to a pathogen(0 – 20 days)

2. How the no. change after your body has destroyed the pathogen (25 – 40 days)

3. How the no. of antibodies change on the 2nd exposure to the same pathogen (Day 65)

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Steps of immunitySteps of immunity

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What do you think is the What do you think is the difference between difference between

natural immunity and natural immunity and artificial immunity?artificial immunity?

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Fighting diseaseFighting diseaseNATURAL IMMUNITY

This is when antibodies are produced by a person when needed or they are passed on by the mother during pregnancy.

ARTIFICIAL IMMUNITY

A vaccine with dead microbes is injected – the body is “tricked” into producing antibodies ready for the real thing. This is called PASSIVE IMMUNISATION

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Using AntibioticsUsing AntibioticsAntibiotics can be used to kill bacteria.

However, there are two problems:

1) Overuse of antibiotics can lead to bacteria becoming resistant

2) Antibiotics have no effect on a virus, like the common cold. A virus must be allowed to “run its course”.

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What problems do you What problems do you think there might be with think there might be with

antibiotics in fighting antibiotics in fighting disease?disease?

Do you think their effect lasts for Do you think their effect lasts for ever?ever?

Can they treat Can they treat allall infectious infectious diseases?diseases?

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Antibiotic resistanceAntibiotic resistance

• Antibiotics are made naturally by bacteria/fungi to destroy other micro-organisms. E.g. penicillin

• However – bacteria become resistant to an antibiotic. So new antibiotics have to be developed every time a bacteria becomes resistant.

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‘‘Superbugs’Superbugs’• Superbugs are bacteria that are resistant

to all know antibiotics – except one. But we don’t know how long that will last!

• Just a tiny change in one gene can cause a bacteria to mutate – and it can become a superbug.

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• One superbug by itself won’t do much damage – but if it reproduces quickly then a large bacteria population could be resistant to an antibiotic.

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2 things increase the risk of 2 things increase the risk of antibiotic resistance:antibiotic resistance:

1. People taking antibiotics they don’t really need.

2. People not finishing their course of antibiotics

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Write down at least 3 ideas Write down at least 3 ideas of how we can stop of how we can stop

superbugs spreading in our superbugs spreading in our hospitalshospitals

19/04/23How can we stop the How can we stop the superbugs?superbugs?

1. Developing new antibiotics

2. Better hygiene in hospitals to reduce risk of infection

3. Only prescribing antibiotics when a person really needs them

4. Education! .......Making sure people understand why it’s important to finish their course of antibiotics

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Re-cap of last lesson: Re-cap of last lesson: antibioticsantibiotics

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19/04/23Title: Title: How do vaccinations How do vaccinations work?work?

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Key words• • • •

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So why is it taking so So why is it taking so long to find a cure for long to find a cure for

HIV?HIV?

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Hmmmm….Hmmmm….

HIV is an uncommon type of virus called a retrovirus, and drugs developed to disrupt the action of HIV are known as antiretrovirals or ARVs.

These come in a variety of formulations designed to act on different stages of the life-cycle of HIV.

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The AIDS virus mutates rapidly, which makes it extremely skilful at developing resistance to drugs.

To minimize this risk, people with AIDS are generally treated with a cocktail of ARVs that attack the virus on several fronts at once.

ARVs have proved very effective at treating people with AIDS. But they are not a cure. If treatment is discontinued the virus becomes active again, so a person on ARVs must take them for life.

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Title: Title: Vaccination policyVaccination policyBy the end of the lesson… Grade WILFOutline the key features of a

vaccination policyC

Identify different viewpoints that people may have

B

Challenge /Analyse strategies and viewpoints

Produce counter arguments based on logical/or empathetic grounds

A

A*

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MMR vaccineMMR vaccine

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Your taskYour task

1. Look at the MMR vaccine article in textbook.

2. Use the information to fill in your table.

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Writing plan:

1. Outline in general what a vaccine policy is and how it may be implemented

2. Produce a logistic plan of how you would carry one out.

3. Give a list of benefits to the public of a vaccination policy.

4. Outline 2 or more areas of society that may benefit from a vaccine policy.

5. Give 2 differing points of view that parents may have. Try to explain their reasons.

6. Explain why it is important that a large majority of the population is vaccinated against a contagious disease.

7. Evaluate in your opinion the rights of a person to refuse a vaccine with the right of the general public to be protected