Unit 3.2.6 - The Bodies Defense System

Question 1

What on pathogens trigger an immune response?

Answer 1

The foreign antigens on its surface

Question 2

What is an antigen?

Answer 2

A large complex molecule that triggers an immune response - like a glycoprotein

Question 3

What is an antibody?

Answer 3

A protein secreted by B cells in response to a non-self antigen

Question 4

Describe the structure of an antibody?

Answer 4

Four polypeptide chains joined together by disulphide bond, two of the chains are long heavy longs and two of the chains are short lighter chains.

Question 5

What is the same about all antibodies?

Answer 5

The constant region

Question 6

What is different between all antibodies?

Answer 6

The variable region

Question 7

What is the shape of the variable region determined by?

Answer 7

The sequence of amino acids which make up the primary structure of the protein

Question 8

Draw the structure of an antibody?

Answer 8

See flash card 21

Question 9

What type of white blood cell carries out phagocytosis?

Answer 9

A phagocyte

Question 10

What are the five steps in phagocytosis?

Answer 10

1. ) The phagocyte recognises the foreign antigens on the pathogen
2. ) It moves its cytoplasm around the pathogen engulfing it in a phagosome
3. ) A lysosome fuses with the phagosome
4. ) It releases lysosomal enzymes
5. ) These enzymes begin to break down the pathogen

Question 11

What is the pathogen contained in during phagocytosis?

Answer 11

A phagosome

Question 12

How do phagocytes activate T cells?

Answer 12

After phagocytosis they present the foreign antigens on their surface which activates the T cells

Question 13

Name two other types of white blood cells, not including phagocytes?

Answer 13

B cells and T cells

Question 14

What type of response do the T cells form?

Answer 14

The cellular response

Question 15

What type of response do the B cells form?

Answer 15

The humoral response

Question 16

What cells form the cellular response?

Answer 16

T cells

Question 17

What forms the humoral response?

Answer 17

B cells and the production of antibodies

Question 18

What are the two types of T cells?

Answer 18

Killer and helper cells

Question 19

What do the killer T cells do?

Answer 19

They attach to antigens on the pathogen and kill the cell

Question 20

What do helper T cells do?

Answer 20

They activate the B cells

Question 21

How do B cells becomes activated?

Answer 21

They have antibodies on their surface, when they bind with foreign antigens they form antigen-antibody complexes and so become activated

Question 22

When the B cells become activated what cells do they produce and how?

Answer 22

They divide by mitosis, so that the new cells are genetically identical and have the same antibodies which are specific to the antigens on the pathogen, these are called plasma cells

Question 23

What three ways do antibodies help the immune response?

Answer 23

1. ) coating the pathogen to make it easier for the phagocyte to engulf
2. ) coating the pathogen to prevent it from entering host cells
3. ) bind to and neutralise toxins produced by the pathogens

Question 24

What do both B and T cells produce which mean you become immune to a pathogen after coming in contact with it?

Answer 24

Memory cells

Question 25

Why do memory cells mean you are immune to a pathogen?

Answer 25

If you ever come in to contact with the same antigen again they recognise it and produce plasma cells much faster than before so you don't get ill and so you are immune

Question 26

What type of response are plasma cells known as?

Answer 26

Primary response

Question 27

What type of response are memory cells known as?

Answer 27

Secondary response

Question 28

If the primary or secondary response slower and why?

Answer 28

Primary because there aren't many B cells making the correct antibody so they have to divide which all takes time

Question 29

Why are you usually given a second injection?

Answer 29

To boost the number of memory cells in your blood so that you can still quickly produce plasma cells to fight of the pathogen

Question 30

What is meant by antigenic variation?

Answer 30

When pathogens can change their antigens on their surface

Question 31

What is bad about antigenic variation?

Answer 31

If the antigens change it means you will no longer have memory cells that will recognise the pathogen and so you will no longer be immune

Question 32

Why do you have to have a new flu vaccination each year?

Answer 32

The influenza virus shows antigenic variation and so the antigens keep changing so even though you have memory cells for the pathogen one year they may have changed by the next so you need a new vaccination

Question 33

What is a vaccine?

Answer 33

It is when dead or weakened pathogens or antigens are put into the body (often by an injection) to provide protection for individuals and populations against disease

Question 34

Describe how a vaccine gives you immunity to a certain pathogen?

Answer 34

When the body comes into contact with the foreign antigens it activates the T cells which then activate the B cells The B cells then divide to produce plasma which they produce antibodies to destroy the pathogen Memory cells are also produced by the B and T cells so that the secondary response happens much faster and you don't get ill from the pathogen and so are immune

Question 35

What is herd immunity?

Answer 35

When a high percentage of the population is vaccinated so that there are fewer people to carry the disease and pass it on so fewer people will develop the disease

Question 36

What is a monoclonal antibody?

Answer 36

An antibody that is specific to one particular antigen and can be mass produced for medical purposes

Question 37

How can monoclonal antibodies be used to treat cancer?

Answer 37

You can attach anti-cancer drugs onto the end of the monoclonal antibodies, this means when the antibody binds to the specific antigens on the surface of the tumour the drug can be delivered to the cancerous cells

Question 38

Why is it good to use monoclonal antibodies to treat cancer?

Answer 38

The drug will only accumulate where there are cancer cells and so reducing damage to normal cells in the body, reducing the side effects

Question 39

Other than to treat cancer what is another use for monoclonal antibodies?

Answer 39

They are used in pregnancy tests to detect very small amounts of the hormone HCG

Question 40

Why are babies often immune to diseases which they haven't had yet?

Answer 40

They have the antibodies from their mother for the first few months of their lives

Question 41

Why are babies only protected with their mothers antibodies for the first few months of their lives?

Answer 41

They will have foreign antigens on their surface and so the babies immune system will start to destroy the antibodies