Immunology

Question 1

What is meant by tolerance?

Answer 1

Immunological unresponsiveness to an antigen.

Question 2

What are the main physical barriers to infection?

Answer 2

Reproductive, respiratory and digestive tract and the skin.

Question 3

What cells produce mucus?

Answer 3

Goblet cells

Question 4

Into what two sections is the immune system divided?

Answer 4

Innate and adaptive.

Question 5

Which cells are phagocytic?

Answer 5

Monocytes, dendritic cells and macrophages

All granulocytes

Question 6

Describe the process of phagocytosis.

Answer 6

Phagocyte surrounds and engulfs bacterium, encasing it in intracellular phagosome.
Lysosome containing cocktail of powerful hydrolytic enzymes fuses with phagosome.
Enzymes digest bacterium, destroying it.
Debris is released into extracellular space by exocytosis and acts as a signal to other immune cells.

Question 7

Into what two cell types can a monocyte mature?

Answer 7

Dendritic cells

Macrophages

Question 8

What is the most abundant WBC?

Answer 8

Neutrophil

Question 9

For how long do neutrophils generally circulate in the blood before undergoing apoptosis?

Answer 9

6 Hours

Question 10

Where are all blood cells produced?

Answer 10

Bone marrow

Question 11

In what type of infection are eosinophils mainly involved?

Answer 11

Parasitic

Question 12

What type of WBC is a mast cell?

Answer 12

Granulocyte

Question 13

What type of hypersensitivity are mast cells involved with?

Answer 13

Type 1- Allergy

Question 14

What is the least common granulocyte cell?

Answer 14

Basophil

Question 15

Name 4 non-specific humoral molecules which protect against infection.

Answer 15

1. Lysins
2. Growth inhibitors
3. Enzyme inhibitors
4. Complement proteins

Question 16

What causes redness upon injury?

Answer 16

When macrophages encounter a pathogen, they release chemicals to alert other cells to invasion. These chemicals often restrict blood flow away from the site of invasion. This causes redness

Question 17

Describe the adaptive immune system.

Answer 17

Specific- Exhibits immunological memory and antibody production

Question 18

Describe the innate immune system.

Answer 18

Non-specific- Produces the same response for every infection.

Question 19

What are the three compliment pathways.

Answer 19

Classical
Alternative
Lectin

Question 20

Give a brief overview of the complement pathway.

Answer 20

Over 20 individual proteins, working together in an enzyme cascade to form a membrane attack system. This basically works by punching a hole in the pathogen, preventing it from maintaining homeostasis and killing it.

Question 21

What is the argument for the complement system being part of the innate immune system?

Answer 21

It does not change its mechanism at all over time, with subsequent infections.

Question 22

What is the argument for the complement system being part of the adaptive immune system?

Answer 22

The adaptive immune system activates these pathways

Question 23

Which complement pathway is an effector mechanism of the adaptive immune system?

Answer 23

Classical

Question 24

Which complement pathways are effector mechanisms of the innate immune system?

Answer 24

Alternative and Lectin

Question 25

What is the central event in activation of the complement system?

Answer 25

Proteolysis (breakdown into smaller peptides) of complement protein C3

Question 26

What is meant by MAC?

Answer 26

Membrane attack complex

Question 27

By what two mechanisms of action can a natural killer cell destroy a target cell?

Answer 27

1. Secretion of perforin onto target cell, creating a MAC which bore hole into the cell. Secretion of enzymes into this hole will digest the target cell. 2. Protein FasL on NK cell binds to protein Fas on target cell. This binding sends a signal to target cell to commit suicide.

Question 28

What are cytokines?

Answer 28

Chemicals used in cell-to-cell communication, specifically in communicating presence of invading microorganism.

Question 29

What are the three mechanisms of action of cytokines?

Answer 29

1. Autocrine- self activation 2. Paracrine- Activation of local cell 3. Endocrine- Spread via circulation and activation of far away cell.

Question 30

What are the functions of the lymphatic system?

Answer 30

1. Drainage 2. Absorption and transport of fats and fatty acids. 3. Immunity

Question 31

What are the primary lymphoid organs?

Answer 31

Bone marrow and Thymus

Question 32

What are the immunological functions of the bone marrow?

Answer 32

Production of Lymphocytes and storage of B lymphocytes.

Question 33

What is the immunological function of the thymus?

Answer 33

Site of maturation of T Lymphocytes.

Question 34

What are the secondary lymphoid organs?

Answer 34

Spleen, Tonsils. Lymph Nodes, Peyer's patch.

Question 35

What is the main immunological function of the spleen?

Answer 35

Filter the blood of antigens, defective microorganisms and worn out RBCs

Question 36

What is one secondary lymphoid organ feature which the spleen lacks?

Answer 36

High Endothelial Venules

Question 37

What are High Endothelial Venules?

Answer 37

Doorway to which B and T cells enter secondary lymphoid organs from the blood.

Question 38

What is the role of CD4+ T cells?

Answer 38

To assist B cells

Question 39

What is the role of CD8+ T cells?

Answer 39

Cytotoxic cells which destroy invading cells

Question 40

How do memory B cells work?

Answer 40

Once sensitised to a particular antigen, if presented with that antigen again, will produce antibodies that bind to it with greater affinity.

Question 41

How do memory T cells work?

Answer 41

Once sensitised to a particular antigen, if presented with that antigen again, will produce a quicker response.

Question 42

In terms of lymphocytes, what does the term naïve mean?

Answer 42

The lymphocytes have not yet been in contact with a particular antigen and so are immunologically inexperienced.

Question 43

What is the difference between active and passive immunity?

Answer 43

Active immunity involves the host producing its own antibodies and T lymphocytes to combat infection. Passive immunity involves adoptive transfer of antibodies and T lymphocytes from an outside source, to combat infection.

Question 44

What is meant by opsonisation?

Answer 44

Making a foreign cell more susceptible to phagocytosis

Question 45

What are the five classes of antibody?

Answer 45

IgG, IgM, IgE, IgA, IgD

Question 46

What is the function of IgG?

Answer 46

Opsonisation

Question 47

What is the function of IgM?

Answer 47

Opsonisation and fixing of complement cascade

Question 48

What is the function of IgE?

Answer 48

Protection from parasites, involved in allergy and anaphylaxis.

Question 49

What is the function of IgA?

Answer 49

Protection of mucosal surfaces

Question 50

Describe the structure of an antibody?

Answer 50

Light Chain, either lambda or kappa. Longer Heavy chain (5 types)- Decides which class of antibody it is. Antigen binding site and Fc binding site Disulphide bonds

Question 51

What is the difference between B cells and plasma cells?

Answer 51

B cells mature into plasma cells which are then responsible for antibody production

Question 52

What is an antigen?

Answer 52

Any substance capable of provoking an immune response.

Question 53

Why is tolerance of T cells more important than tolerance of B cells?

Answer 53

Generally, antibody production by plasma cells (differentiated B cells) is stimulated by a form of T cell (T helper cell)