Diseases and Immunity (Topic 10)

Question 1

Pathogen

Answer 1

disease-causing organism

Question 2

What are the mechanical barriers?

Answer 2

Skin, hairs in the nose

Question 3

What are the chemical barriers?

Answer 3

Mucus, stomach (hydrochloric) acid

Question 4

How do cells act as barriers?

Answer 4

Phagocytes (phagocytosis) and Lymphocytes (agglutination)

Question 5

Antigens

Answer 5

Proteins and other substances projecting from their cell membrane that are specific to that type of cell

Question 6

What is the function of lymphocytes?

Answer 6

They can ‘read’ the antigens and make antibodies once they recognise that they are foreign. Antibodies are a complementary shape to the antigens on the surface of the pathogenic cell.The antibodies attach to the antigens and cause agglutination (clumping together) so they cannot move very easily. At the same time, chemicals are released that signal to phagocytes that there are cells present that need to be destroyed.

Question 7

How do lymphocytes make you immune?

Answer 7

It make take a few days to make the antibodies at first, but after the first time they will make ‘memory cells’. This means that, in the case of reinfection by the same type of pathogen, antibodies can very quickly be made in greater quantities. It does not work with all disease-causing microorganisms as some of them mutate fairly quickly and change the antigens on their cell surfaces.

Question 8

What is active immunity?

Answer 8

Making antibodies and developing memory cells for future response to infection is known as active immunity. There are two ways to get active immunity: become infected with a pathogen and make antibodies; vaccination. It provides slow acting and long-lasting immunity.

Question 9

What is passive immunity?

Answer 9

This is when ready-made antibodies, from another source, are introduced to the body and it is a fast-acting, short-term defence against a pathogen. Ways to get it: mother to infant via breast milk; injected antibodies for certain diseases. The body does not make its own antibodies or memory cells.

Question 10

What happens in Type 1 diabetes?

Answer 10

Their immune system is targeting and destroying the pancreatic cells which are responsible for making the insulin, eventually leading to dangerously high glucose levels in the blood.

Question 11

How can diseases be caused by the immune system?

Answer 11

The immune system start to attack the body’s own cells. Specific body cells are targeted by lymphocytes and antibodies are made against them.

Question 12

What is vaccination?

Answer 12

Protection against specific diseases and boost the body’s defence against infection from pathogens without the need to be exposed to dangerous diseases that can lead to death.

Question 13

How does vaccination work?

Answer 13

Vaccines allow a dead or altered form of the disease-causing pathogen, which contains specific antigens, to be introduced into the body. In this weakened state, the pathogen cannot cause illness but can provoke an immune response.

Question 14

What is herd immuunnity/

Answer 14

If a large enough percentage of the population is vaccinated, it provides protection for the entire population because there are very few places for the pathogen to breed.

Question 15

Ways to prevent the spread of pathogens?

Answer 15

Hygienic food preparation, personal hygiene, waste disposal, sanitation.

Question 16

How does hygienic food preparation work to prevent the spread of pathogens?

Answer 16

1. Keep food cold so bacteria and fungi are produced more slowly
2. Cook food well.
3. Wash your hands.
4. Cover food to prevent flies landing on it.

Question 17

How does personal hygiene work to prevent the spread of pathogens?

Answer 17

1. Wash your hands.
2. Use tissue when sneezing.
3. Dispose of tissues quickly.

Question 18

How does waste disposal work to prevent the spread of pathogens?

Answer 18

1. Collect waste in a sealed container.
2. Rubbish should be stored (after collection) away from human habitation.
3. Remove bins for landfill disposal or burning regularly.

Question 19

How does sanitation work to prevent the spread of pathogens?

Answer 19

1. Plumbing and drains.
2. Sewage should be treated before released into the environment.