Transcript Revise_B2_in_15_mins[1]

START REVISING HERE
Microorganisms are Very Small
Biggest
FUNGI
Smallest
BACTERIA
VIRUSES
(On a needle)
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.
Some microorganisms are Pathogenic
Pathogenic means they cause diseases
• Athletes foot, Thrush
• Smallpox , Flu
• Tuberculosis, Cholera
Fungal
Viral
Bacterial
If you are infected with one of
these 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
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)
Getting used to
their Petri dish
food supply
Rapid growth
Lots of food,
water, warmth
and space
Time
More dying
than growing
So why don’t we get ill all the time?
• Skin stops them getting into our
bodies and makes antibacterial
chemicals
• Tears also kill them
BURP!
• Stomach acid kills them
And if that doesn’t stop them – WBCs will:
That’s me, the white one
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 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
Arghhh
Foreign blood cell
being attacked
‘’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’’
If it’s 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, that’s better’’
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 and natural selection
ALMOST FORGOT: Antibiotics don’t kill VIRUSES
‘’I’ve had chickenpox, why can’t I catch it again’’?
‘’Because your now immune to it silly’’
1. First Infection
How does that happen?
Antibodies attach to nasty
microbes & kill them
WBC make
antibodies
2. If there is a second Infection
Me
again
Yeh and I
remember
you ‘cos I’m
a memory
cell
The differences between 1 & 2 are:
1. 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 think I’m
dying!
Once killed, the WBC’s
become memory cells
which remember the
microbes antigens
Zap Bang Wallop!
I’m dead!
This is what an Immune Response looks like
Memory cells
become active
Antibody
numbers
Memory cells
created here
First encounter
with pathogen
Second
encounter with
pathogen
Pathogen
rapidly
destroyed
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…NASTY
MO
MO
Original antigens
New antigens
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!
5. what about memory cells?
1.
4
2
3
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
4. Antibodies attach to
the pathogen’s antigens
(markers). They neutralise
the pathogen or attract
phagocytotic WB Cells
2. Sometimes there
are side effects
3.White Blood cells
produce antigens which
match the pathogens
antigens (markers)
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 don’t get sick; this is immunity.
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
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
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
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 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
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 transport blood into the heart
• Arteries transport blood away from the heart
• Coronary arteries supply heart cells with blood
Why Do Arteries and Veins Look Different?
thick layer of
muscle and
elastic fibres
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 need
thin walls. They also have
valves which prevent
blood moving backwards
ARTERY
thick outer
layer
thin outer
wall
VEIN
AND FINALLY, THE LAST SLIDE
thin layer of
muscle and
elastic fibres
Bad Lifestyle = Increased Risk of a Heart Attack
• Risk factors: Smoking, lack of exercise, high salt/fat diet & family history
1. Bad
lifestyle
2. Build up of
fat in artery
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
6. Heart attack
takes place
5. Heart muscle
cells begin to die
The End
AND
Don’t forget to do as many past
papers as you can.
Check your answers using the
mark schemes
Good Luck