B1.3/4/5 - Diseases and immunisation

Question 1

How are infectious diseases caused?

Answer 1

Infectious diseases are caused by microorganisms that invade our body. These harmful microorganisms are parasites that live in our body to gain nutrients and shelter. We say our body is the host for the parasites.

Question 2

How are non-infectious diseases caused?

Answer 2

Non-infectious diseases are not caused by parasites invading our body. Causes of non-infectious diseases include:

• vitamin deficiency
• mineral deficiency
• body disorders
• genetic inheritance

Question 3

What is a tumour?

Answer 3

Tumours occur when you have cancer. A tumour is formed by body cells that keep on dividing to form an abnormal mass, which is a tumour.

Question 4

Many cancers are non-infectious. How may one reduce the risk of getting cancer?

Answer 4

• Sunbathe a little, but make sure you do not burn
• Avoid eating too much fat and do not become overweight
• Avoid eating too much red meat and processed food
• Eat plenty of fresh fruit and vegetables
• Take regular exercise
• Avoid drinking too much alcohol

Question 5

What is a benign tumour and what is a malignant tumour?

Answer 5

• A tumour is benign when it does not spread to other parts of the body.(easier to deal with as it can be cut out)
• A tumour is malignant when it does spread to other parts of the body.(harder to deal with as there may be cancer cells all over the body.

Question 6

What is the host?

Answer 6

The body the parasites invaded and live on.

Question 7

What is a parasite?

Answer 7

A parasite is a harmful microorganism that causes an infectious disease.

Question 8

What causes infectious diseases, in more detail?

Answer 8

Infectious diseases are called by parasitic microorganisms that infect you. They disease-causing microorganisms are called pathogens. These invading pathogens may damage cells and release chemicals called toxins.

Question 9

Name 4 types of pathogens and what sort of disease they may cause

Answer 9

• Fungi (e.g cause athletes foot)
• Bacteria (e.g cause cholera)
• Viruses (e.g cause flu)
• protozoa (e.g cause malaria)

Question 10

Some infectious diseases are spread from person to person through vectors. What is a vector and give an example

Answer 10

A vector is something that spreads disease from person to person and an example of this is a mosquito and malaria. A female mosquito spreads a parasite that causes malaria.

Question 11

How does knowing how a vector spreads a disease help humans control it in terms of malaria?

Answer 11

• People would sleep under mosquito nets and use insect repellent
• Use insecticides to kill mosquito’s

Question 12

What is incidence of disease?

Answer 12

The incidence of disease is the rate at which new cases of a certain type of disease occur within a population each year. It is usually measured in number of cases per 10,000 or 100,000 people.

Question 13

Why may disease spread quicker in a hotter climate?

Answer 13

In a hot or warm place vectors may multiply quicker, meaning there are more vectors to spread the disease.

Question 14

What are antibiotics?

Answer 14

Antibiotics are chemicals produced by some fungi and bacteria, to kill or prevent the growth of other bacteria or fungi. They are used to kill pathogens in our body when we have an infectious disease.

Question 15

What was the first antibiotic discovered and when?

Answer 15

Penicillin was the first antibiotic discovered and was discovered in the 1920s and has been used to treat people since the 1940s. After that many others have been found.

Question 16

Why don’t antibiotics work on viruses?

Answer 16

Antibiotics do not work on viruses because they are not a bacteria or fungi. Also viruses have no metabolic reactions to be prevented and they do not grow.

Question 17

What do antiviral drugs do?

Answer 17

Antiviral drugs inhibit the replication of of viruses inside the host.

Question 18

Doctors should not prescribe antibiotics when they are not needed and patients must finish the whole course even when they start to feel better. Why must antibiotics be used carefully?

Answer 18

If Antibiotics are not used carefully the bacteria starts to become resistant to the antibiotics. The resistant strains of bacteria develop.
-MRSA is an example of this. MRSA is a strain of bacterium that lives on our skin and can cause a bad infection if it enters a wound. It is resistant to most antibiotics and is hard to deal with, but antiseptics can kill it. This is why we must clean wounds and our skin with antiseptics.

Question 19

How does our body prevent pathogens entering it?

Answer 19

Our body has barriers that prevent pathogens entering it, these include:

• skin
• stomach acid
• mucus in the airways
• tears
• blood clotting when you cut yourself

Question 20

What deals with pathogens if they do get inside our body?

Answer 20

The immune system

Question 21

White blood cells are part of the immune system. What two types of white blood cells do we have in our body?

Answer 21

• Phagocytes engulf (ingest) the pathogens

- Lymphocytes produce antibodies or antitoxins.

Question 22

What are antibodies?

Answer 22

Antibodies are proteins. Each type of antibody can destroy a specific type of bacterium or virus.

Question 23

Each type of antibody can destroy a specific type of bacterium or virus. Why is this?

Answer 23

• Each type of pathogen has antigens (protein) with a particular shape on its surface.
• Each type of antibody (protein) has a particular shape and can lock onto a particular antigen.
• Your immune system makes the right kind of antibodies to lock onto the particular antigens that are in your body.

Question 24

Once you have recovered from an infection you have immunity to it. Why is this?

Answer 24

This is because your immune system now knows how to fend off that particular pathogen so if the same pathogen enters your body again, your body makes antibodies so quick that the pathogen is destroyed before it makes you feel ill.

Question 25

What is the point of having an immunised or vaccinated?

Answer 25

An immunisation makes you immune to a disease before you get the disease and become at risk.

Question 26

How does a vaccination or immunisation work?

Answer 26

• A small amount of dead pathogen is injected into your body. These pathogens still have antigens on them.
• Your white bloods cells recognise the antigens on the pathogens and respond to it by making antibodies.
• If later on the live pathogens gets into your body your white bloods cells can quickly make the correct antibodies. These antibodies then destroy the pathogen before they make you ill.

Question 27

What is a mutation?

Answer 27

The changing of the structure of a gene, bacteria etc.

Question 28

How can a mutation effect a vaccine?

Answer 28

Some viruses such as the flu mutate often. This means its structure changes so that when it re-enters your body, your immune system does not recognise the virus so it can make you ill again. This is why new vaccines are made every year for certain viruses.

Question 29

What is active immunity?

Answer 29

When you make your own antibodies. For example, after having an infection or having an immunisation/vaccine.

Question 30

What is passive immunity?

Answer 30

This is when you do not make your own antibodies. For example, you may be injected with antibodies made in a lab. This is done when a pathogen make kill you before you can make your own antibodies. Active immunity lasts longer than passive immunity.

Question 31

What is an antigen?

Answer 31

A toxin or other foreign substance which induces an immune response in the body.

Question 32

What is epidemic and what is pandemic?

Answer 32

An epidemic is when a virus or bacteria spreads across a country.
A pandemic is when a virus or bacteria spreads across a continent.