02/08/15

B2 – Keeping HealthyB2 – Keeping Healthy

W Richards

The Weald School

(OCR 21st Century)

B2.1 How do our bodies resist infection?

02/08/15MicrobesMicrobesMicrobes are micro organisms that can cause diseases. They can enter the body in a number of ways:

…or other natural openings…

They can be breathed in through the mouth or nose

They can enter through cuts or bites in the skin

Microbes (or the poisons they produce) damage cells – these are the symptoms of a disease.

02/08/15DiseaseDiseaseA 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):

VirusesBacteria

• 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

Bacteria GrowthBacteria 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 min30 mins

1 hr1:302:002:303:003:304:004:305:00

141664

No of bacteria

Time

02/08/15Producing antibodiesProducing antibodies

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

You’re going down

02/08/15Specific antibodiesSpecific 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.

Microbe

Antigen

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?

02/08/15VaccinationsVaccinationsVaccinations 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

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.

“Antimicrobials” are chemicals used to kill or inhibit microbes. For example:

FungiFungi 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!):

02/08/15How bacteria become immuneHow bacteria become immuneAlthough 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!!

Bacteria

Penicillin

No effect!!

Words – offspring, resistance, killed, antibiotics, reproduce

The rise of MRSANo. of MRSA cases

Year

02/08/15Researching new medicinesResearching new medicinesBefore new drugs can be approved they have to go through three stages. What are the advantages and disadvantages of each stage?

3. Is it safe for humans? Human volunteers are tested on, both with and without the disease.

1. Is it toxic? Tests are done on cells

2. Is it safe for animals? Animal tests are carried out

02/08/15PlacebosPlacebosClinical 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...

02/08/15An example of drug development - An example of drug development - ThalidomideThalidomide

Mat Fraser, comedian and actor

Tony Melendez, guitarist

02/08/15Developing new drugsDeveloping new drugsBefore 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.

B2.3 What factors affect Heart Disease?

“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)…

4) … and to the rest of the body (where oxygen is removed)

5) After the oxygen and glucose have been removed for respiration the blood is sent back to the heart and starts again

The Circulatory systemThe 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 capillariesArteries carry high pressure blood away from the heart. They have smaller lumen and

no valves.

Veins carry low pressure blood back to the heart. They have thinner, less elastic walls and

have valves to prevent backflow of blood.

Capillaries have thin walls (one cell thick) to allow

glucose and oxygen to pass through. Also used to

connect arteries to veins.

“Lumen”

Measuring Blood PressureBlood 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.

Heart disease

Cholesterol

High Blood PressureHigh 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 LifestyleWho is the most likely to die of heart disease in the next 20 years?

Heart Disease RisksClearly, the risk of heart disease

depends on a number of factors:

1) Lack of _________

2) Eating foods high in _________ fats

3) ______ factors, e.g. if your parents had it

4) Whether or not you _______

Words – smoking, exercise, genetic, saturated

Factors that affect the risk of heart disease can be identified via large-scale genetic studies.

02/08/15DrugsDrugs

Why do people use illegal drugs?

02/08/15Cannabis: Pros and consCannabis: Pros and consIn 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:

02/08/15Drugs Research ProjectDrugs Research ProjectExplain and give examples for the following:

1) Why do people use illegal drugs?

2) What are the drawbacks of illegal drugs? What can they cause?

3) Choose one drug and discuss how it affects the human body

B2.4 Keeping a Healthy Water Balance

HomeostasisHomeostasis 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

Effectors (muscles and sweat glands) carry out the response

Receptors in the skin detect the external temperature

Temperature detectors in the brain detect the blood temperature

The brain coordinates a response using hormones

Receptor – Processing Centre - Effector

Controlling Water ContentLow 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 achieved.

“Negative Feedback”

Controlling Water Content 2High 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 achieved.

“Negative Feedback”

Controlling Water Levels

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.

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.

Words – ADH, negative feedback, water, sweating, dehydration, cells, urine