B2 – Keeping Healthy

B2 – Keeping Healthy
(OCR 21st Century)
M Barker
Shirebrook Academy
B2.1 How do our bodies resist infection?
Microbes are micro organisms that can cause diseases. They
can enter the body in a number of ways:
They can be
breathed in
through the
mouth or nose
…or other
Microbes (or the
poisons they
produce) damage
cells – these are the
symptoms of a
They can enter
through cuts or
bites in the skin
A 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 a type of PATHOGEN (a microbe that causes disease):
• 1/1000th mm big
• 1/1,000,000th mm big
• Living cells (some are harmless)
• Genetic info inside a protein coat
• Grow very quickly
• Not affected by antibiotics
• Affected by antibiotics
• Release poisons
• Examples: food poisoning,
tetanus, sore throats
• Examples: colds, flu, polio,
chicken pox
Bacteria Growth
Bacteria can grow and multiply at very quick rates, especially
inside the human body.
Imagine bacteria could double every 15 minutes. Draw a graph
of how many you would have at the following times:
No. of bacteria
0 min
30 mins
1 hr
No of
Producing antibodies
You’re going
Step 1: The white blood cell “sees”
the pathogen (microbe)
Step 2: The cell produces
antibodies to “fit” the pathogen
Step 3: The antibodies fit onto the
pathogens and cause them to “clump”
Step 4: The pathogens are
“eaten” by the white blood cells
Specific antibodies
Antibodies are specific – they will neutralise the microbe
they have been made for. They do this by recognising
the antigen on the surface of the microbe.
Once the body has made the antibody “memory cells” can
make it again very quickly if needed, which protects you
from catching the disease again.
B2.2 What are vaccine and antibiotics?
Vaccinations work by injecting a _____ or weakened form of a
________ into the body. The body is then “tricked” into
producing _______. The memory cells then remember the
antigen so that, if the person catches the real disease, they
are ready for it.
In order to prevent an ______, sometimes large numbers of
the population can be ______. A possible problem with this is
that people can feel ____ ______.
Words – antibodies, vaccinated, side effects,
epidemic, dead, microbe
Using Antimicrobials
“Antimicrobials” are chemicals used to kill or inhibit microbes.
For example:
1) Antibacterials kill bacteria but
overuse of them can lead to
bacteria becoming resistant (e.g.
the MRSA “superbug”). This means
that antibiotics must be used
sparingly. They also have no effect
on virii.
2) Antifungals can be used to treat
fungal infections like Athlete’s
foot. Fungi can also become
immune over time.
Fungi can also cause unwanted conditions. These conditions
can be treated with anti-fungal medicine and antibiotics.
Some examples (don’t look if you’re faint hearted!):
How bacteria become immune
Although vaccinations and antibiotics are useful in the fight
against pathogens, bacteria and virii can mutate to form a new,
resistant “strain”:
1) Mutation – some strains of
bacteria can genetically
mutate to develop _______
to the antibiotics.
2) The non-resistant bacteria
are _____ by the _______.
3) The resistant bacteria
_______ and pass on their
mutations to their ______.
Don’t use antibiotics unless
you need to!!
Words – offspring, resistance,
killed, antibiotics, reproduce
The rise of MRSA
No. of
Researching new medicines
Before new drugs can be approved they have to go through
three stages. What are the advantages and disadvantages of
each stage?
1. Is it toxic? Tests are done on cells
2. Is it safe for animals? Animal tests are
carried out
3. Is it safe for humans? Human
volunteers are tested on, both with and
without the disease.
Clinical trials can be done by “open label” (i.e. everyone knows
what’s being given to who) or in different ways:
1) Blind trials
Patients do not know which drugs they are taking – a real drug
or a “placebo”
2) Double blind trial
Neither the doctors or the patients know if they are taking
the real drug
Placebos offer an ethical dilemma as a patient might be
sick and still be given a “dummy” pill. Also, you might
notice if you had a placebo as you wouldn’t get the side
effects of normal drugs...
An example of drug development -16/03/2016
Mat Fraser,
comedian and actor
Tony Melendez,
Developing new drugs
Before a new drug can be approved it has to go through a
strict testing process. Consider the example of thalidomide:
Mid 1950s
Animal testing using thalidomide was undertaken.
Tests showed that it was safe but the tests were
“inadequate” – no tests were done on pregnant animals
Late 1950s
Thalidomide prescribed to pregnant mothers to help
sleep and morning sickness problems
Early 1960s
Babies are born with birth defects and the drug was
banned worldwide. Around 12,000 deformed
Thalidomide babies born, 4,000 die in first year.
Mid 1960s
Tests show that Thalidomide can help leprosy
sufferers and it is still used today for this purpose.
B2.3 What factors affect Heart Disease?
“Double Circulation”
1) Blood gets pumped
from the heart to the
lungs and picks up oxygen
5) After the oxygen and
glucose have been removed
for respiration the blood is
sent back to the heart and
starts again
2) The blood is then
taken back to the
heart which needs its
own blood supply…
3) The heart pumps
the blood to the
intestine (where
oxygen and glucose
are removed)…
4) … and to the rest of
the body (where oxygen
is removed)
The Circulatory system
The circulatory system is responsible
for pumping ______ around the body.
We need blood to be taken around the
body because blood contains ________
and _______. These are needed so
that all the ____ in our bodies can
produce _____ through _________.
Blood is pumped at high pressure and
measuring the pulse rate can tell us the
heart rate.
Words – energy, blood, glucose,
respiration, oxygen, cells
Arteries, veins and capillaries
Arteries carry high pressure
blood away from the heart.
They have smaller lumen and
no valves.
Capillaries have thin walls
(one cell thick) to allow
glucose and oxygen to pass
through. Also used to
connect arteries to veins.
Veins carry low pressure blood back to the
heart. They have thinner, less elastic walls and
have valves to prevent backflow of blood.
Measuring Blood Pressure
Blood pressure
measurements are
taken in terms of
“Pressure when
heart is contracting
over pressure when
heart is relaxed”.
Healthy blood pressures are
defined as being within a range, due
to the fact that every person is
Heart disease
High Blood Pressure
High blood pressure is a condition where the ______ and
blood vessels experience extra strain. It can be caused by:
• Excess weight or lack of exercise
• High stress levels
• _____
• Excess _______
• Diets that are high in saturated ___, sugar or salt
Long term high blood pressure can cause blood vessels to
weaken or even ______ and can lead to heart disease.
Words – alcohol, burst, smoking, heart, fat
Heart Disease and Lifestyle
Who is the most likely to die of heart disease in the next 20
Heart Disease Risks
Clearly, the risk of heart disease
depends on a number of factors:
1) Lack of _________
2) Eating foods high in _________
3) ______ factors, e.g. if your parents
had it
4) Whether or not you _______
Factors that affect the risk of heart disease can be
identified via large-scale genetic studies.
Words – smoking, exercise, genetic, saturated
Why do people use
illegal drugs?
Cannabis: Pros and cons
In January 2004 cannabis was changed from a class B drug to
a class C drug. Some people think that Cannabis should be
made legal. What are the pros and cons of cannabis?
Drugs Research Project
Explain and give examples for the following:
1) Why do people use illegal drugs?
2) What are the drawbacks of illegal drugs? What can they
3) Choose one drug and discuss how it affects the human body
B2.4 Keeping a Healthy Water Balance
Homeostasis means “controlling internal
conditions” and it is achieved using the
body’s nervous and hormonal systems.
Some examples of things that need to
stay constant:
• Body temperature
• Amount of sugar in the body
• Amount of water in the body
The body does all these things so that its
cells can continue to work normally. Let’s
look at temperature and water content in
more detail…
Homeostasis in different conditions
Body Temperature
Receptors in the skin detect the
external temperature
Temperature detectors in the brain
detect the blood temperature
The brain coordinates a response
using hormones
Effectors (muscles and sweat glands)
carry out the response
Receptor – Processing Centre - Effector
Controlling Water Content
Low blood water level causes a high
salt concentration
Receptors in the hypothalamus
detect the high salt content
More ADH is secreted into the blood
by the pituitary gland
The kidney becomes more permeable
to water so more is absorbed.
The bladder fills with a small
quantity of urine
Normal blood water level is
“Negative Feedback”
Controlling Water Content 2
High blood water level causes a low
salt concentration
Receptors in the hypothalamus
detect the low salt content
Less ADH is secreted into the blood
by the pituitary gland
The kidney becomes less permeable
to water so more is absorbed.
The bladder fills with a large
quantity of urine
Normal blood water level is
“Negative Feedback”
Controlling Water Levels
Our bodies control water content using a “____
______” mechanism. Controlling water content is
important as many process that occur in _____
need the correct water content in each cell.
Factors affecting water content of our bodies:
• External temperature – e.g. is the person _______?
• Intake of _______ and food
• How much is lost through breathing and _______
• Alcohol – this can suppress ADH which leads to __________ due to the
body producing more urine
• Drugs, e.g. Ecstasy, which causes increased ____ production.
Words – ADH, negative feedback, water, sweating,
dehydration, cells, urine