revise b2 in 15 mins
TRANSCRIPT
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START REVISING HERE
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Microorganisms are Very Small
Biggest Smallest
When millions of
them grow in one
place then you
can see them
Colonies of Bacteria
and Fungi growing
in an agar plate.
Agar jelly is their
food.
FUNGI VIRUSESBACTERIA
(On a needle)
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Some microorganisms are Pathogenic
Pathogenic means they cause diseases
Athletes foot, Thrush Fungal Smallpox , Flu Viral Tuberculosis, Cholera Bacterial
If you are infected with one ofthese you will show symptoms:
E.g. runny nose, high temp,
spots, sneezing etc.
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
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How do bacteria Grow?
Real Fast !!!
Rapid growth
Lots of food,
water, warmth
and space
Growth rate = death rate(running out of food or too muchexcretory products)
More dying
than growing
Just give them: WARMTH FOOD WATER (Not O2)
Getting used to
their Petri dish
food supply
1 cell 2 4 8 16 32 64 128 256 512 - In just 3 Hrs
------------ And it looks like this -------------
Time
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So why dont we get i l l al l the time? Skin stops them getting into our
bodies and makes antibacterialchemicals
Tears also kill them
Stomach acid kills them
And if that doesnt stop them WBCs will:
BURP!
Thats me, the white
one
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The Immune System
Its me your friendly neighbourhood
white blood cell again. This is how wekill microbes
1. We find them, surround them and
digest them, BURP! (phagocytosis)
2. Some of us make chemicals
called antibodies that stick on to
the outside of microbes. Each
microbe has a different covering or
antigens. Different antibodies
recognises the shape of each
different antigen. Death follows
AND
Foreign blood cell
being attacked
Arghhh
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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
If its a fungus it will have as much food, space
and water as it wants. And what next?
-- Itch Itch Scratch Scratch --
And this arrow is NOT
pointing at your feet
Better get the bio
yoghurt out
Ahh, thats better
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Antibiotic Resistant Bacteria Superbugs MRSA
These are all the exactly the same thing,
NASTY bacteria that cannot be killed by Antibiotics
click for video
Final resistant
population
Why are they so common?
People take ABs for colds & flu
People dont finish the course
Its just normal variation and natural selection
ALMOST FORGOT: Antibiotics dont kill VIRUSES
I h d hi k h I h i i ?
http://www.sumanasinc.com/scienceinfocus/antibiotics/antibiotics_fla.htmlhttp://www.sumanasinc.com/scienceinfocus/antibiotics/antibiotics_fla.html -
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Ive had chickenpox, why cant 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 Imdying!
Once killed, the WBCs
become memory cells
which remember themicrobes antigens
1. First Infection
2. If there is a second Infection
Me
again
Yeh and I
remember
you cos Im
a memory
cellZap BangWallop!The differences between 1 & 2 are:
1. Antibodies are made slowly and you mayfeel ill before all the MOs are all killed2. 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
Antibody
numbers
Second
encounter with
pathogen
First encounter
with pathogen
Memory cells
become activePathogen
rapidlydestroyed
Memory cells
created here
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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 rapidlyNASTY
Original antigens New antigens
MO MO
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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!
1.
3
2
4
5. what about memory cells?
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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 types of 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 dont get sick; this is immunity.
4. Antibodies attach to
the pathogens antigens
(markers). They neutralise
the pathogen or attract
phagocytotic WB Cells
3.White Blood cells
produce antigens whichmatch the pathogens
antigens (markers)
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Drug Safety Taking any drug involves some risk.
Side effects can be minor, severe or even cause death
Vaccinations have the same risks but the risk to the individual isoutweighed 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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Testing Drugs
Drugs are tested for safety (side effects) and effectiveness (if it works)
Testing involves 3 stages: On human cells (relatively cheap & quick and may indicate how safe it is) On animals (gives more information on safety and effectiveness) On people in a clinical trial (gives even more data & information)
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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Clinical (Human) Trials
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
Veins transport blood into the heart
Arteries transport blood away from the heart
Coronary arteries supply heart cells with blood
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
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Why Do Arteries and Veins Look Different?
thin outer
wall
thick layer of
muscle and
elastic fibres
thick outer layer
thin layer of
muscle andelastic fibres
ARTERY
VEIN
Arteries carry blood at high
pressure, thick wallsprevent them bursting,
elastic fibres allow them to
stretch and go back to their
normal shape
Veins carry blood at low
pressure so only need
thin walls. They also
have valves which
prevent blood movingbackwards
AND FINALLY, THE LAST SLIDE
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Bad Lifestyle = Increased Risk of a Heart Attack
Risk factors: Smoking, lack of exercise, high salt/fat diet & family history
A heart attack animation
4. Cells now
starved of oxygen
1. Bad
lifestyle
2. Build up of
fat in artery
5. Heart musclecells begin to die
3. Blood flow is now
reduced to the heart
muscle cells
6. Heart attack
takes place
The End
heart attack - simple version
http://www.medindia.net/animation/heart_attack.asphttp://www.youtube.com/watch?v=7_OQWfGvanQhttp://www.youtube.com/watch?v=7_OQWfGvanQhttp://www.medindia.net/animation/heart_attack.asp -
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AND
Dont forget to do as many past
papers as you can.
Check your answers using the
mark schemes
Good Luck
http://www.youtube.com/watch?v=7_OQWfGvanQhttp://www.youtube.com/watch?v=7_OQWfGvanQhttp://www.youtube.com/watch?v=7_OQWfGvanQhttp://www.youtube.com/watch?v=7_OQWfGvanQhttp://www.youtube.com/watch?v=7_OQWfGvanQhttp://www.youtube.com/watch?v=7_OQWfGvanQ