1. This is in addition to your revision!
This is a big topic
You have been warned

2. Microorganisms are Very Small
Biggest
Smallest
BACTERIA
VIRUSES
FUNGI
(On a needle)
Colonies of Bacteria and Fungi growing in an agar plate.
Agar jelly is their food.
When millions of them grow in one place then you can see them

3. Some microorganisms are Pathogenic Pathogenic means they cause diseases
If you are infected with one of these you will show symptoms:
E.g. runny nose, high temp, spots, sneezing etc.
Athletes foot, Thrush Fungal
Smallpox , Flu Viral
Tuberculosis, Cholera Bacterial
Some diseases are caused by the things we do: Over eating, cigarettes, alcohol, drugs These are called LIFESTYLE diseases:
Obesity, Heart disease, lung cancer.
Remember: YOU can change your lifestyle

4. How do bacteria Grow? Real Fast !!!
Just give them: WARMTH – FOOD – WATER (Not O2)
1 cell – 2 – 4 – 8 – 16 – 32 – 64 – 128 – 256 – In just 3 Hrs
And it looks like this
Growth rate = death rate (running out of food or too much excretory products)
Getting used to their Petri dish food supply
Rapid growth
Lots of food, water, warmth and space
More dying than growing
Time

5. Antimicrobials Eg: antibiotics, vaccines, antiseptics
Any substance that inhibits (slows or stops) the growth of bacteria, fungi or bacteria,
Eg: antibiotics, vaccines, antiseptics

6. So why don’t we get ill all the time
So why don’t we get ill all the time? Skin, antiseptic tears, mucus in our nose and windpipe, stomach acid, hairs & earwax all stop them getting in to our body.
And if that doesn’t stop them – White Blood Cells from our immune system will:
That’s me, the white one

7. Antibiotic Resistant Bacteria – Superbugs – MRSA These are all the exactly the same thing, NASTY bacteria that cannot be killed by Antibiotics
Why are they so common?
People take AB’s for colds & flu People don’t finish the course
click for video
Final resistant population
It’s just normal variation, natural selection & mutations
ALMOST FORGOT: Antibiotics don’t kill VIRUSES

8. Foreign blood cell being attacked
The Immune System
‘’ It’s me your friendly neighbourhood white blood cell again. This is how we kill microbes’’
1. We find them, surround them and digest them, BURP! (phagocytosis)
AND
2. Some of us make chemicals called antibodies that stick to microbes. Each microbe has antigens ( molecules on their surface). Antibodies recognise the shape of each different antigen & stick to them. Death follows
Arghhh
Foreign blood cell being attacked

9. ‘’OK, but what if I’m too sick and my immune system isn’t stopping them’’?
If it’s a bacteria take a course of antibiotics –
And don’t stop just because you feel better
And you might experience side effects, even death!!
And, they might kill all your good microbes.
‘’SO WHAT, THE ONLY GOOD MICROBE IS A DEAD MICROBE’’
If a fungus is left it will have as much food, space and water as it wants. ‘’And what next’’? GROWTH
-- Itch Itch Scratch Scratch --
Better get the bio yoghurt out
‘’Ahh, that’s better’’
And this arrow is NOT pointing at your feet

10. Yeh and I remember you ‘cos I’m a memory cell
‘’I’ve had chickenpox, why can’t I catch it again’’? ‘’Because your now immune to it silly’’ How does that happen?
WBC make antibodies
Antibodies attach to nasty microbes & kill them
I think I’m dying!
Once killed, the WBC’s become MEMORY CELLS which remember the microbes antigens
1. First Infection
2. If there is a second similar Infection
Me again
Yeh and I remember you ‘cos I’m a memory cell
Zap Bang Wallop!
The differences between 1 & 2 are:
Antibodies are made slowly and you may feel ill before all the MO’s are all killed
2. Antibodies are made really fast and you don’t get ill at all. You are IMMUNE
I’m dead!

11. This is what an Immune Response looks like
Memory cells become active
Pathogen rapidly destroyed
Memory cells created here
Antibody numbers
First encounter with pathogen
Second encounter with pathogen

12. Vaccines & Vaccinations
A vaccination make you immune from a disease
A vaccine contains either:
A dead MO, parts of a MO, or a weakened MO
WHY?
They ALL contain the MO’s antigens/markers
They all lead to memory cells being made
Some Problem Microbes
Flu Virus – mutates rapidly (changes it’s antigens)
HIV virus – Attacks the immune system
and also mutates rapidly…very NASTY MO MO
New antigens
Original antigens

13. Testing Drugs
Drugs are tested for safety (side effects) and effectiveness (does it work?)
Testing involves 3 stages:
On human cells (relatively cheap & quick and may indicate how safe it is)
On animals (gives information on safety and effectiveness)
On people in a clinical trial (gives info on dosage, side effects)
Issues with Drug Tests
Can take 10 years to get a new drug to market
VERY expensive: staff & clinical trials, salaries, looking after animals, hospital & lab costs, security
Ethical issues with using live animals
Ethical issues with testing it on humans,
especially if a placebo is involved.
Must be approved & licensed by the government

14. Can you describe what's happening in the picture
Can you describe what's happening in the picture? When you have written your 5 descriptions, check your answers on the next slide. No peeking! 1. 3 2 4
5. what about memory cells?

15. No Peeking until you have completed the first slide
1. Vaccine containing weakened,
dead pathogen or parts of it. Each of these has the pathogens antigens (markers). All induce an immune response
2. Sometimes there are side effects
5. Special White Blood Cells called memory cells are produced so when you come in contact with the real pathogen they REMEMBER IT and produce antibodies SO FAST you don’t get sick; this is immunity.
4. Antibodies attach to the pathogen’s antigens (markers). They neutralise the pathogen or attract phagocytotic WB Cells
3.White Blood cells produce antigens which match the pathogens antigens (markers)

16. Clinical or Human Trials
Increasingly more reliable results
(less risk of bias)
Open label: Everyone knows who has the drug
Blind: Only the doctors know who has the drug
Double Blind: No one knows who has the drug

17. Drug Safety
Taking any drug involves some risk & we all react differently cos we are all genetically different
Side effects can be minor, severe or even cause death
Vaccinations have risks too, but the risk to the individual is outweighed by the benefits to the rest of the population.
If 95% of the public are vaccinated it stops a disease from spreading and can lead to its eradication (disappearance)
Smallpox has been completely eradicated over the whole world

18. Why Do Arteries and Veins Look Different?
Arteries carry blood at HIGH pressure, thick walls prevent them bursting, elastic fibres allow them to stretch and go back to their normal shape
thin outer wall
thick layer of muscle and elastic fibres
thick outer layer
thin layer of muscle and elastic fibres
ARTERY
VEIN
Veins carry blood at LOW pressure so only thin walls are needed. They also have valves which prevent blood moving backwards
Capillaries, tiny blood vessels that carry oxygen & food to cells & remove carbon dioxide from cells

19. Running a Clinical Trial
Trials have to be designed scientifically to be fair & reliable tests
Participants put in to two groups
Participants chosen randomly (increases reliability)
One group gets the drug the other no drug, (the control group)
A control group allows the groups/drugs effect to be compared
If it’s a totally new drug the control group has a placebo
A placebo looks exactly like the real drug but contains no drug
Placebos raise ethical issues; if the new drug may cure a serious disease and does work, people in the control group may die

20. The Circulatory System
The heart is made of muscle cells.
Every cell needs oxygen and glucose to make energy (respiration)
The blood transports oxygen and glucose to every cell
Blood leaves the heart under high pressure and returns under low pressure
Veins carry blood into the heart
Arteries carry blood away from the heart
Coronary arteries supply heart cells with blood

21. An incubator has to control a babies temperature just like your body
Thermostat
Set at 37oC
Temperature sensor
Heater
A typical homeostasis graph
This is the control system sequence
Temperature drops below 37oC
Sensor detects drop & messages thermostat
Thermostat messages heater to switch on
Temperature rises to 37oC
Temperature rises above 37oC
Sensor detects the rise & messages thermostat
Thermostat messages heater to switch off
Temperature drops
And the cycle continues
37oC

22. Bad Lifestyle = Increased Risk of a Heart Attack
Risk factors: Smoking, lack of exercise, high salt/fat diet & family history
2. Build up of fat in artery
1. Bad lifestyle
3. Blood flow is now reduced to the heart muscle cells
A heart attack animation
4. Cells now starved of oxygen
heart attack - simple version
5. Heart muscle cells begin to die
6. Heart attack takes place

23. Water Control Remember Water IN = Water OUT
IN: drinks, food, respiration
OUT: Urine, faeces, breathing, sweating
(exercise is dehydrating)
All of these effect the amount of water in the blood plasma and the kidney controls it.

24. Homeostasis & Control Systems
Your body needs to keep conditions inside your body the same - otherwise you will feel ill & be ill
THIS IS CALLED HOMEOSTASIS
REMEMBER IT!
What needs to be kept under control?
Levels of: glucose, water, salt, urea, CO2 & O2
-Also: temperature, pH & blood pressure
The underlined ones are in this syllabus

25. Control System Terms/Sequence
Stimulus – A factor that changes (e.g. Temp rises)
Receptor (sensor) - Detects the change
Processing Centre – Decides the action to be taken
Effector – Produces the response
Response - The change produced (e.g. Temp drops)
Negative Feedback – Part of a control system that reverses changes to bring them back to normal. Allows a quicker response & keeps the value closer to the normal value
You should be able to recognise these in an incubator and in the kidney/water control system

26. ADH, the Kidney& Water Control
Stimulus
Detected by water receptors
in the processing centre (brain)
Pituitary
Gland Effector (brings about the response)
Response:
Less pee,
blood water increases
More pee,
blood water decreases
Gland Effector (brings about the response)
Learn all the key words and understand how the flow chart works

27. Drugs and ADH Learn This
Alcohol makes people pee a lot of dilute urine by lowering ADH production
They become dehydrated
Ecstasy does the opposite
Increases ADH production
Therefore, stops you peeing
So, ecstasy users should not drink too much water, they will dilute their blood too much and pass out. OR WORSE!!

28. AND Don’t forget to do as many past papers as you can
AND Don’t forget to do as many past papers as you can. Check your answers using the mark schemes And if you’re aiming for an A* or B go through each line of the syllabus/specification (find it on the OCR web site) Good Luck

30. Not Yet or not fully covered in this resource
Epidemiological Studies (disease causes and their transmission)
Correlations
The scientific method
Risks and benefits (to individuals and society)
Ethics
AND FINALLY, THE LAST SLIDE