Immune System

Question 1

What are antigens?

Answer 1

Proteins on the surface of cells which generate an immune response when detected in the body

Question 2

What type of cells do antigens identify?

Answer 2

Pathogens
Abnormal god cells
Toxins
Foreign cells from other individuals

Question 3

What are pathogens?

Answer 3

Organisms which cause disease

Question 4

What are phagocytes?

Answer 4

A type of white blood cell (macrophage) found in blood and tissues

Question 5

What are the first cells to respond to an immune system trigger?

Answer 5

Phagocytes

Question 6

Are phagocytes specific or non-specific?

Answer 6

Non-specific

Question 7

What are antibodies?

Answer 7

Quaternary proteins which are produced in response to a specific antigen

Question 8

What are lymphocytes?

Answer 8

Type of white blood cell (include T and B cells)

Question 9

Are lymphocytes specific or non specific?

Answer 9

Specific

Question 10

Where do T cells mature?

Answer 10

Thymus gland

Question 11

Where do B cells mature?

Answer 11

Bone marrow

Question 12

Which type of immune response involves B cells?

Answer 12

Humoral response

Question 13

What type of immunity involves T cells?

Answer 13

Cell mediated immunity

Question 14

What is the first stage of immune response?

Answer 14

Phagocytosis

Question 15

Describe phagocytosis

Answer 15

Phagocyte recognises antigens on pathogen
Phagocytes cytoplasm surrounds and engulfs pathogen
Pathogen is contained in phagocytic vacuole
Phagocytic vacuole fuses with lysosome
Lysozymes break down pathogen
Phagocytes displays antigens on its surface to active other immune system cells

Question 16

What is the second stage of immune system response?

Answer 16

Phagocytes activate T cells
T cells have receptor proteins which bind to complementary antigens presented by the phagocyte- this activates the T cell

Question 17

What do helper T cells do?

Answer 17

Release chemical signals which activate and stimulate phagocytes, cytotoxic T cells and B cells

Question 18

What do cytotoxic T cells do?

Answer 18

Kill abnormal and foreign cells

Question 19

What is the 3rd step in the immune response?

Answer 19

T cells activate B cells

Question 20

Describe how T cells activate B cells

Answer 20

Helper T cells release substances to activate the B cell
The B cell is fully activated when its antibodies (on its surface) bind to antigens
The B cells divide into plasma cells

Question 21

What is the 4th stage of immune response?

Answer 21

B cells make antibodies

Question 22

How are monoclonal antibodies made?

Answer 22

Plasma cells secrete antibodies specific to antigen

They bind to form antigen antibody complex

Question 23

What is agglutination? How many binding sites do antibodies have?

Answer 23

Pathogens clumped together by antibodies

2 binding sites

Question 24

How does agglutination speed up the immune system response?

Answer 24

Phagocytes can carry out phagocytosis on many pathogens at once

Question 25

What is primary immune response?

Answer 25

When an antigen enters the body for the first time and activates the immune system

Question 26

Why is primary immune response slow?

Answer 26

There aren't plasma,cells which can produce specific antibodies to the antigen

Question 27

How does primary response lead to a quicker secondary response/immunity?

Answer 27

Memory T and B cells are produced and remain in the body | They produce specific antibodies to the antigen

Question 28

What do vaccines contain?

Answer 28

Dead or weak forms of pathogen

Question 29

How do vaccines provide immunity?

Answer 29

They contain antigens which cause the body to produce memory cells

Question 30

What is herd immunity?

Answer 30

When many individuals are immune from a disease so there are less people to catch it from- reduced occurrence of disease

Question 31

Why are injected vaccines likely to be more effective than oral vaccines?

Answer 31

Direct into blood stream | Tablets may be broken down by enzymes or too big to be absorbed into the blood

Question 32

Why are booster vaccines given?

Answer 32

To ensure memory cells are produced

Question 33

What is antigenic variation? Give an example

Answer 33

``` Influenza (flu) Mutation in pathogen gene change in shape of antibodies on surface Memory cells d not recognise antigens Body has to carry out primary response ```

Question 34

What is active immunity?

Answer 34

Immune system making its own antibodies

Question 35

What are the two types of active immunity?

Answer 35

Natural - immunity after catching a disease/exposure to antigen Artificial - receiving a vaccine

Question 36

What are the two types of passive immunity?

Answer 36

Natural - babies receive antibodies from breast milk (colostrum) Artificial - injected with somebody else's antibodies for some diseases e.g. Tetanus

Question 37

What is passive immunity?

Answer 37

Receiving antibodies from a different organism

Question 38

Explain differ need between active and passive immunity

Answer 38

Active: body makes antibodies, requires exposure to antigen, takes time for immunity, memory cells produced, long term Passive: antibodies received, no exposure to pathogen required, immediate, memory cells not produced, short term

Question 39

What are monoclonal antibodies?

Answer 39

Identical antibodies produced from a single group of genetically identical B cells/plasma cells

Question 40

Give two examples of the use of monoclonal antibodies in medicine

Answer 40

``` Targeted medication Medical diagnosis (pregnancy test) ```

Question 41

What hormone is tested for in pregnancy tests?

Answer 41

hCG

Question 42

How do monoclonal antibodies treat cancer?

Answer 42

Cancer cells have tumour markers (antigens) Monoclonal antibodies attached to drug Binds only to cancer cells

Question 43

What are ELISA tests used for?

Answer 43

Medical diagnosis- see if antibodies are present for a certain antigen

Question 44

Explain a basic Elisa test

Answer 44

Antibody has enzyme attached to it Enzyme reacts with substrate to produce a coloured product Colour change shows presence of antigen/antibody

Question 45

Describe the ELISA test for HIV

Answer 45

``` HIV antigen in bottom of well Blood plasma added Well is washed out Secondary antibody with enzyme attached is added Washed out Colour Change - positive ```

Question 46

What is HIV? What does it lead to and when?

Answer 46

Human immunodeficiency virus - immune system deteriorates and eventually fails. Leads to AIDS when low levels of helper T cells

Question 47

What cells does HIV infect and use as host cells?

Answer 47

Helper T cells

Question 48

Describe the structure of HIV

Answer 48

``` RNA Few proteins and enzymes, reverse transcriptase Capsid Envelope Attachment proteins ```

Question 49

Describe HIV replication

Answer 49

Attachment protein binds to receptor on Helper T cell Capsid released into cell, releases RNA into cytoplasm RNA acts as template, complementary strand of DNA made using reverse transcriptase DNA is inserted into T cell DNA Host cell enzymes make viral proteins and new HIV viruses

Question 50

How do antibiotics kill bacteria?

Answer 50

Interfere with metabolic reactions | Target enzymes and ribosomes

Question 51

Why do antibiotics only target bacterial cells and not human cells?

Answer 51

Bacterial cells contain different enzymes

Question 52

Why do antibiotics not work on viruses?

Answer 52

Viruses contain very little of own enzymes - use host cells enzymes Cannot inhibit human enzymes

Question 53

There is no cure for HIV. How is HIV progression slowed down?

Answer 53

Antiviral drugs | Target virus specific enzymes (reverse transcriptase)