B2 Keeping Healthy

1
B2 Keeping Healthy

• Revision and key points

2
Key Aims

• To know how the body fights infections
• Understand the arguments about vaccines
• Know how superbugs develop
• How new drugs are developed and tested
• How heart disease is caused and how scientists
  know

3
Activity 1

• For each of the key ideas, on the A2 sheet, in
  groups of
• 2-4 put down everything you can about each one.

• To know how the body fights infections
• Understand the arguments about vaccines
• Know how superbugs develop
• How new drugs are developed and tested
• How heart disease is caused and how scientists
  know

4
Micro-organisms
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The Bodies Defence

• The first line of defence Passive immunity
• skin
• chemicals in tears
• chemicals in sweat
• stomach acid
• The Second line of defence Active immunity
• white blood cells
• ingest pathogens and destroy them
• produce antibodies to destroy pathogens
• produce antitoxins that neutralise the toxins
  released by pathogens

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Remember!

• The pathogens are not the disease - they cause
  the disease.
• White blood cells do not eat the pathogens - they
  ingest them.
• Antibodies and antitoxins are not living things -
  they are specialised proteins.

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Phagocytes / Macrophages

• Phagocytes can pass easily through blood vessel
  walls into the surrounding tissue and move
  towards pathogens or toxins. They then either  
• ingest and absorb the pathogens or toxins, or
• release an enzyme to destroy them.
• Having absorbed a pathogen, phagocytes may also
  send out chemical messages that help nearby
  lymphocytes to identify the type of antibody
  needed to neutralise them.  

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Lymphocyte

• LymphocytesPathogens contain certain chemicals
  that are foreign to the body, called antigens.
  Each lymphocyte carries a specific type of
  antibody - a protein with a chemical fit to a
  certain antigen. When a lymphocyte with the
  appropriate antibody meets the antigen, the
  lymphocyte reproduces quickly to make many copies
  of the antibody that neutralises the pathogen.  
• Antibodies neutralise pathogens in a number of
  ways  
• They bind to them and damage or destroy them.
• They coat pathogens, clumping them together so
  that they are ingested easily by phagocytes.
• They bind to the pathogens and release chemical
  signals to attract more phagocytes.
• Once the body has made an antibody that
  recognises a particular microorganism, it is able
  to make it again very quickly. This means that if
  the microorganism infects the body again more
  antibodies are made rapidly. This protects the
  body against that microorganism - you are immune
  to it.  

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Microbes Attack

• Describe the curve of the graph
• On top plot the curve of the antibodies production

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Microbes and Antibodies
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Vaccine Action
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The Common Cold and HIV

• Some common diseases like influenza (flu) and the
  common cold are caused by viruses. These mutate
  quickly, which changes their surface proteins.
  This makes it almost impossible to develop a
  permanent vaccine against them. A new flu vaccine
  has to be developed every year, after the strain
  has been analysed
• HIV is the virus that causes AIDS. It is
  particularly difficult to develop a vaccine
  against HIV. The virus not only mutates very
  quickly, but damages the infected persons immune
  system.  

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Vaccine Policy

• What are the arguments for and against using
  vaccines

• Against
• Some vaccines linked to mild side effects
• Can have serious side effects leaving people
  disabled
• Could have an allergic reactions
• MMR vaccine linked to autism, an unproven study
  made the link

• For
• Prevent people getting ill
• Prevent deaths
• Prevent people being permanently disabled
• Prevent diseases spreading
• Get rid of diseases from the population
• Very safe
• Cheaper to vaccinate than treat the illness

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Antibiotics, what do you know?

• What are antibiotics?
• What type of microbes do antibiotics work on?
• How does antibiotic resistance develop?
• What are the two ways to reduce antibiotic
  resistance?
• What is an example of a superbug?

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Antibiotic - Answers

• Chemicals that kill microbes
• Only kill bacteria and some fungi NOT viruses
• Take the antibiotic to kill a bacteria, one
  bacteria is resistant and is not killed, that
  bacteria reproduces till there are loads of them.
• Complete the antibiotic course of drugs and dont
  take them unnecessarily
• A bacteria that is not killed by antibiotics

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Developing New Drugs

• The stages of drug testing
• The drugs are tested using computer models and
  human cells grown in the laboratory. Many
  substances fail this test because they damage
  cells or do not seem to work.
• Drugs that pass the first stage are tested on
  animals. In the UK, new medicines have to be. But
  it is illegal to test cosmetics and tobacco
  products on them. A typical test involves giving
  a known amount of the substance to the animals,
  then monitoring them carefully for any
  side-effects.
• Drugs that have passed animal tests are used in
  clinical trials. They are tested on healthy
  volunteers to check they are safe. The substances
  are then tested on people with the illness to
  ensure they are safe and work.

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Human trials (Higher Tier)

• It is important that the results of clinical
  trials are not influenced by the expectations of
  the people involved. So the volunteers are put
  into two groups at random. Checks are done to
  make sure both groups have a similar gender
  balance and age range.  
• There are two main types of clinical trial. In
  both, one group of volunteers, called the test
  group, receives the new drug. Another, the
  control group, receives the existing drug for
  that illness. If there is no existing treatment,
  the control group is given a fake drug that has
  no effect on the body. This is called a placebo.
  The researchers look for differences between the
  experimental group and control group.  
• Blind trialsIn a blind trial, the volunteers do
  not know which group they are in. But the
  researchers do. The problem is the researchers
  may give away clues to the volunteers without
  realising it. This is called observer bias. It
  can make the results unreliable.  
• Double-blind trialsIn a double-blind trial, the
  volunteers do not know which group they are in,
  and neither do the researchers until the end of
  the trial. This removes the chance of bias and
  makes the results more reliable. But double-blind
  trials are more complex to set up.  

18
Heart Disease

• What is heart disease?
• What are the two types of blood vessels?
• What organ moves blood around the body?
• What are the blood vessels that feed that organ
  called?
• What can build up in these vessels and block
  them?
• What is a heart attack?

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Heart disease - Answers

• An illness of the heart resulting in damage to
  it.
• Arteries and veins
• The Heart
• Coronary arteries
• Fat / cholesterol
• Blocked coronary arteries reducing blood flow
  to the heart heart muscle dies due to lack of
  oxygen.

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The risk factors of heart disease

• What are the risk factors that can lead to heart
  disease?

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Heart Disease

• The causes of heart disease
• High blood pressure
• High Cholesterol
• Not enough exercise
• Stress
• Too much salt
• Overweight
• Smoking
• Family history - genes

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Causes of disease How do we know?

• Epidemiological studies
• Epidemiology is the study of factors affecting
  the health and illness of populations. Doctors
  and scientists carry out epidemiological studies
  to try to determine the lifestyle factors which
  could increase the chances of getting heart
  disease and other illnesses.
• Things to consider  
• The number of people studied must be large enough
  to generate meaningful results - one patient is
  not enough to form a reliable conclusion.
• There needs to be a good match between the test
  and control groups studied. It would wrong if one
  group was all women and the other all men, unless
  perhaps the effect of gender was being studied.
• There might be a correlation between a factor and
  an outcome, but this factor might not be the
  cause of the outcome. For example, pregnant women
  who have iron deficiency tend to produce
  underweight babies. But giving pregnant women
  extra iron in their diet does not seem to make
  their babies heavier.
• It is important that studies are checked by other
  scientists (peer review) and can be repeated by
  them. This makes conclusions more reliable

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What Now?

• Its not enough just to attend the revision
  sessions it helps though!
• Take your notes home and write them out again
  put colour and little sketches to help you
  remember
• Then put them into a mind map
• Then write them out again from memory include the
  sketches
• Check them do this again till you remember
  everything and get it right!