This is in addition to your revision!

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This is in addition to your revision!
This is a big topic You have been warned
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Microorganisms are Very Small
Biggest
Smallest
VIRUSES
BACTERIA
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
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Some microorganisms are PathogenicPathogenic
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, drugsThese are
called LIFESTYLE diseases Obesity, Heart
disease, lung cancer. Remember YOU can change
your lifestyle
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How do bacteria Grow? Real Fast !!!
Just give them WARMTH FOOD WATER (Not O2)
1 cell 2 4 8 16 32 64 128 256
512 - In just 3 Hrs ------------ And it looks
like this -------------
Growth rate death rate (running out of food or
too much excretory products)
Rapid growth Lots of food, water, warmth and space
More dying than growing
Getting used to their Petri dish food supply
Time
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Antimicrobials

• Any substance that inhibits (slows or stops) the
  growth of bacteria, fungi or bacteria,
• Eg antibiotics, vaccines, antiseptics

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So why dont 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 doesnt stop them White Blood Cells
from our immune system will
Thats me, the white one
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Antibiotic Resistant Bacteria Superbugs
MRSAThese are all the exactly the same thing,
NASTY bacteria that cannot be killed by
Antibiotics
Why are they so common? People take ABs for
colds flu People dont finish the course
click for video
Final resistant population
Its just normal variation, natural selection
mutations ALMOST FORGOT Antibiotics dont kill
VIRUSES
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The Immune System
Its 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
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OK, but what if Im too sick and my immune
system isnt stopping them?

• If its a bacteria take a course of antibiotics
  
• And dont 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, thats
better
And this arrow is NOT pointing at your feet
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Ive had chickenpox, why cant I catch it
again?Because your now immune to it
sillyHow does that happen?

• The differences between 1 2 are
• Antibodies are made slowly and you may feel ill
  before all the MOs are all killed
• 2. Antibodies are made really fast and you dont
  get ill at all. You are IMMUNE

Im dead!
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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
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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 MOs antigens/markers
• They all lead to memory cells being made

• Some Problem Microbes
• Flu Virus mutates rapidly (changes its
  antigens)
• HIV virus Attacks the immune system
• and also mutates
  rapidlyvery NASTY

MO
MO
New antigens
Original antigens
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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

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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!
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No Peeking until you have completed the first
slide
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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

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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

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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
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
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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 its 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

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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

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An incubator has to control a babies temperature
just like your body
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
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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
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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.

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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

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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

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ADH, the Kidney Water Control
Learn all the key words and understand how the
flow chart works
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Drugs and ADHLearn 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!!

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ANDDont forget to do as many past papers as you
can. Check your answers using the mark schemes
And if youre aiming for an A or B go through
each line of the syllabus/specification (find it
on the OCR web site)Good Luck
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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