The Immune System

Question 1

What is the immune system made up of?

Answer 1

A network of leukocytes (white blood cells), proteins, tissues and organs.

Question 2

What are the 4 functions of the immune system?

Answer 2

Protect against invading organisms.
Recognise whether something is self or non-self.
Attack.
Destroy.

Question 3

Why do Autoimmune Diseases occur?

Answer 3

When the immune system can no longer recognise whether things are self or non-self and then star attacking healthy cells.

Question 4

What are the two types of Immunity?

Answer 4

Innate and Acquired.

Question 5

Give 6 features of Innate immunity:

Answer 5

Natural Immunity.
Response is non-specific.
Exposure leads to immediate maximal response.
No immunological memory.
Found in nearly all forms of life.
Activates acquired arm of the immune system.

Question 6

Give 5 features of Acquired immunity.

Answer 6

Adaptive immunity.
Pathogen and antigen specific response.
Lag time between exposure and maximal response.
Exposure leads to immunological memory.
Found only in jawed vertebrates.

Question 7

What are the cells in the innate immune system called?

Answer 7

Leukocytes.

Question 8

What are the 2 types of leukocytes involved in the innate immune system?

Answer 8

Granulocytes and Agranulocytes.

Question 9

What % of Leukocytes do Granulocytes make up?

Answer 9

60-70%.

Question 10

What are the 3 types of Granulocytes and what % of Granulocytes do they make up?

Answer 10

Neutrophil, >90% of granulocytes.
Eosinophil, 2-5% of granulocytes.
Basophil, 0-2% of granulocytes.

Question 11

What is the main function of Neutrophil?

Answer 11

Carrying out Phagocytosis.

Question 12

What is the main function of Eosinophil?

Answer 12

Destroying parasites.

Question 13

What is the main function of Basophil?

Answer 13

Inflammation.

Question 14

What are Neutrophil also known as?

Answer 14

Polymorphonuclear leukocytes or PMNs.

Question 15

Where are neutrophil found?

Answer 15

90% found in bone marrow, 3% found in circulation and the rest is found in vascular pools.

Question 16

What is the lifespan of neutrophil?

Answer 16

In blood: 5-6 days, In tissue: 2-3 days.

Question 17

What is phagocytosis?

Answer 17

The process of the ingestion of bacteria, virus or cell debris. Phago = eat, cyte = cell.

Question 18

How does Phagocytosis work?

Answer 18

Phagocytosis is not the “killing machine” it just catches the bad cells. The antigen is engulfed and put into a vacuole, so it is able to contain it in a separate space.

Question 19

What is granule translocation?

Answer 19

The granules in the cytoplasm line the vacuole then fuse with it.

Question 20

What is degranulation or ‘respiratory burst’?

Answer 20

The process which kills the antigen.

Question 21

What happens after degranulation?

Answer 21

The vacuole is opened up and the degraded antigen is released back into the blood.

Question 22

What happens to the neutrophil after working on an antigen?

Answer 22

Commits cell suicide.

Question 23

What are the two types of Agranulocytes?

Answer 23

Lymphocytes and Monocytes.

Question 24

What is the difference between Monocytes and Macrophages?

Answer 24

They are the same cell but when they are in the blood they are known as Monocytes and when they are in the tissue they are known as Macrophages.

Question 25

What % of leukocytes do agranulocytes make up?

Answer 25

5-15%.

Question 26

How do Monocytes/Macrophages work?

Answer 26

They express pattern recognition receptors called Toll-like receptors (TLR), which recognise pathogen-associated molecular patterns (PAMPs). Anything binding to TLR activates the monocytes/macrophages.

Question 27

What is the lifespan of monocytes?

Answer 27

Circulate in the blood for 1-3 days.

Question 28

What is the main function of monocytes / macrophages?

Answer 28

They release the messenger substance (cytokines) in phagocytosis, therefore able to tell other components of the immune system what is happening and whether they need to come to the site of infection.

Question 29

What does being an Antigen Presenting Cell mean?

Answer 29

They can communicate with an acquired arm to "tell" it what it is fighting.

Question 30

What are Natural Killer Cells?

Answer 30

Most lymphocytes belong tot he acquired arm of the immune system, but Natural Killer Cells belong to the innate arm of the immune systems they have no immunological memory.

Question 31

What % of the lymphocyte population to Natural Killer Cells make up?

Answer 31

5-20%

Question 32

What do Natural Killer Cells do?

Answer 32

Natural Killer Cells destroy a variety of tumour and virus infected spontaneously, they do not need to recognise the foreign matter to attack it. They bind to the surface of the infected cell, release perforin which activates apoptosis.

Question 33

What is apoptosis?

Answer 33

Cell suicide.

Question 34

What happens if the micro-organism gets past the innate immune defence?

Answer 34

The Acquired Immune System is required.

Question 35

Why is there a lag time in the acquired immune system?

Answer 35

There may only be one cell out of 5 billion that recognises the virus and therefore that cells has to make more before it can respond.

Question 36

What is the role of Antigen Presenting Cells (APCs)?

Answer 36

To display/present the invading antigen to the acquired arm of the immune system to activate it.

Question 37

How doe APCs work?

Answer 37

Incorporating the antigen protein on to their cell surface and forming major histocompatibility complex (MHC) II.

Question 38

What cells have MHC I and why is it important?

Answer 38

All cells in the body have MHC I which is how cells recognise self cells from non-self cells.

Question 39

Why does the innate arm of the immune system communicate with the acquired immune system?

Answer 39

To try and mount a more targeted and specific immune response to the antigen.

Question 40

What type of cell is present in the Acquired Immune System?

Answer 40

Lymphocytes.

Question 41

What re the main two types of lymphocyte?

Answer 41

T cells and B cells.

Question 42

Where do T cells mature?

Answer 42

The thymus.

Question 43

What % of blood lymphocytes do T cells make up?

Answer 43

60-80%.

Question 44

What is the responsibility of T cells?

Answer 44

Cell-mediated (intracellular) immune response.

Question 45

What do T cell produce?

Answer 45

Memory cells.

Question 46

What are the three main types of T cells?

Answer 46

T helper subset, T cytotoxic subset and T regulatory subset.

Question 47

What do T helper cells do?

Answer 47

Orchestrate and co-ordinate the immune response, they do not commit cell suicide.

Question 48

What do T cytotoxic do?

Answer 48

Bind to an skill antigen specific infected cells. Like Natural Killer Cells, cytotoxic cells release perforin therefore commit cell suicide.

Question 49

What do T regulatory do?

Answer 49

Help to regulate / switch off the immune system response to avoid chronic inflammation.

Question 50

Why can T regulatory cells switch off the immune response?

Answer 50

Because the immune response may start killing healthy cells.

Question 51

What is the difference between Type 1 & Type 2 T cells?

Answer 51

Type 1 and Type 2 T cells release different types of cytokines.