1. B2 – Keeping Healthy (OCR 21st Century) W Richards The Weald School
25/03/2017
B2 – Keeping Healthy
(OCR 21st Century)
W Richards
The Weald School

2. B2.1 How do our bodies resist infection?

3. Microbes
25/03/2017
Microbes are micro organisms that can cause diseases. They can enter the body in a number of ways:
Microbes (or the poisons they produce) damage cells – these are the symptoms of a disease.
They can be breathed in through the mouth or nose
They can enter through cuts or bites in the skin
…or other natural openings…

4. Disease
25/03/2017
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):
Bacteria
Viruses
1/1000th mm big
Living cells (some are harmless)
Grow very quickly
Affected by antibiotics
Examples: food poisoning, tetanus, sore throats
1/1,000,000th mm big
Genetic info inside a protein coat
Not affected by antibiotics
Release poisons
Examples: colds, flu, polio, chicken pox

5. 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:
Time
No. of bacteria
0 min
30 mins
1 hr
1:30
2:00
2:30
3:00
3:30
4:00
4:30
5:00 1 4 16 64
No of bacteria
Time

6. Producing antibodies You’re going down
25/03/2017
You’re going down
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

7. Specific antibodies Microbe Antigen
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Microbe
Antigen
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.

8. B2.2 What are vaccine and antibiotics?

9. Words – antibodies, vaccinated, side effects, epidemic, dead, microbe
Vaccinations
25/03/2017
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

10. 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.

11. Fungi
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!):

12. How bacteria become immune
25/03/2017
Although vaccinations and antibiotics are useful in the fight against pathogens, bacteria and virii can mutate to form a new, resistant “strain”:
Mutation – some strains of bacteria can genetically mutate to develop _______ to the antibiotics.
The non-resistant bacteria are _____ by the _______.
The resistant bacteria _______ and pass on their mutations to their ______. Don’t use antibiotics unless you need to!!
Bacteria
No effect!!
Penicillin
Words – offspring, resistance, killed, antibiotics, reproduce

13. The rise of MRSA
No. of MRSA cases
Year

14. Researching new medicines
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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.

15. Placebos
25/03/2017
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...

16. An example of drug development - Thalidomide
25/03/2017
An example of drug development - Thalidomide
Mat Fraser, comedian and actor
Tony Melendez, guitarist

17. Developing new drugs
25/03/2017
Before a new drug can be approved it has to go through a strict testing process. Consider the example of thalidomide:
Date
Event
Mid 1950s
Late 1950s
Early 1960s
Mid 1960s
Animal testing using thalidomide was undertaken. Tests showed that it was safe but the tests were “inadequate” – no tests were done on pregnant animals
Thalidomide prescribed to pregnant mothers to help sleep and morning sickness problems
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.
Tests show that Thalidomide can help leprosy sufferers and it is still used today for this purpose.

18. B2.3 What factors affect Heart Disease?

19. “Double Circulation”
1) Blood gets pumped from the heart to the lungs and picks up oxygen
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)…
5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again
4) … and to the rest of the body (where oxygen is removed)

20. 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

21. 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.
“Lumen”
Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and have valves to prevent backflow of blood.

22. 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 different.

23. Heart disease
Cholesterol

24. Words – alcohol, burst, smoking, heart, fat
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

25. Heart Disease and Lifestyle
Who is the most likely to die of heart disease in the next 20 years?

26. Words – smoking, exercise, genetic, saturated
Heart Disease Risks
Clearly, the risk of heart disease depends on a number of factors:
Lack of _________
Eating foods high in _________ fats
______ factors, e.g. if your parents had it
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

27. Drugs
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Why do people use
illegal drugs?

28. Cannabis: Pros and cons
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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?
Pros:
Cons:

29. Drugs Research Project
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Explain and give examples for the following:
Why do people use illegal drugs?
What are the drawbacks of illegal drugs? What can they cause?
Choose one drug and discuss how it affects the human body

30. B2.4 Keeping a Healthy Water Balance

31. Homeostasis
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…

32. Homeostasis in different conditions

33. 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

34. Controlling Water Content
Low blood water level causes a high salt concentration
“Negative Feedback”
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 achieved.

35. Controlling Water Content 2
High blood water level causes a low salt concentration
“Negative Feedback”
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 achieved.

36. 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