Immunology

Question 1

What is the function of the immune system?

Answer 1

To protect us from the varying pathogens we face in daily life.

Question 2

Where do lymphocytes originate from?

Answer 2

Lymphocytes originate from the common lymphoid progenitor which is a differentiation of the haematopoietic stem cell in the bone marrow. these lymphocytes include B cells, T cells

Question 3

Where do the granular cells arise from?

Answer 3

Granular cells arise from the common myeloid progenitor. these cells include the neutrophils, basophils, platelets etc. Monocytes give rise to macrophages and dendritic cells.

Question 4

Where does the innate immune response occur?

Answer 4

The innate immune response occurs local to the infection

Question 5

Describe neutrophils

Answer 5

Neutrophils are the first line of defence and have a multi-lobed nucleus. they have bacteriostatic and toxic factors contained within the granules which they release locally or internally to kill bacteria. they move towards the site of infection by chemotaxis which is the response to chemotactic factors released by cells.

Question 6

Describe macrophages

Answer 6

Macrophage means big eater cell. they eat cells and clean up dead neutrophils and also present antigens to T lymphocytes.

Question 7

What is the complement system?

Answer 7

The complement system is a cascade pathway that enhances the killing efficiency of the immune system. the molecules are released by the liver generally.

Question 8

Describe opsonisation

Answer 8

Opsonisation is the coating of a bacteria with complement that makes it “tastier” to a phagocyte to eat.

Question 9

How do cells involved in the innate immune response reach the site of infection?

Answer 9

Cytokine factors allow the tight junctions between blood cells to become leakier.

Question 10

Where does the adaptive immune response occur?

Answer 10

It occurs at the lymphoid organs.

Question 11

Where are B and T cells produced and where do they mature?

Answer 11

B cells are produced in the bone marrow but may leave to mature in the spleen or lymph node, whereas T cells are produced in the bone marrow but mature in the thymus.

Question 12

How does dirty lymph fluid and clean leave the lymph nodes?

Answer 12

Afferent vessels bring in the dirty lymph, efferent vessels take away the clean.

Question 13

Where do B and T lymphocytes reside in a lymph node?

Answer 13

B lymphocytes reside in the periphery germinal area, T lymphocytes reside in the paracortical inner area.

Question 14

What are CD4 and CD8 T cells?

Answer 14

CD4 are the helper T cells which produce an antigen to the B lymphocytes.
CD8 are the cytotoxic killer cells involved in killing virally infected cells.

Question 15

How does apoptosis occur via CD8 T cells?

Answer 15

Class 1 antigens are presented to a CD8 cell by a dendritic cell. the T cell sacrifices the body’s own cells that have been virally infected by injecting perforins then using granzyme from the cell itself to induce apoptosis and scramble the cell’s DNA>

Question 16

What are the five types of antibodies?

Answer 16

IgG- the default
IgA- two antibodies together
IgM- 5 subunits together
IgD
IgE

Question 17

What do B cells do?

Answer 17

B cells produce antibodies that bind to the antigen on a pathogens surface, inactivating it and marking it for destruction. It can differentiate into antigen presenting cells or antibody producing plasma cells. Some remain undifferentiated as memory cells for a quicker secondary immune response in case of re-infection

Question 18

What are eosinophils

Answer 18

Involved in inflammation

Question 19

what are mast cells and histamine involved in?

Answer 19

Mast cells dilate the blood vessels and release histamine which recruits neutrophils and macrophages to the site of infection.

Question 20

What are dendritic cells and basophils?

Answer 20

Dendritic cells present antigens to immune cells whilst basophils play a role in blood clotting.

Question 21

What is inflammation and its function?

Answer 21

it is a reaction to damage to cells or vascularised tissue. it is a response to expel foreign bodies and initiate repair to structural and functional damage.

Question 22

What are the features of inflammation?

Answer 22

Redness- caused by vasodilation
Heat- increased blood flow
Swelling- ECM contains more fluid
Pain- stretching of tissue by oedema, stimulation of pain receptors too
Loss of function- pain and swelling immobilises the area

Question 23

Why inflammation?

Answer 23

Isolates the damaged area, promotes healing and tissue repair.

Question 24

Describe bacterias modes of infection

Answer 24

Antigenic mimicry
Antigenic masking
Antigenic shift
Encapsulation
Evasion of host immune response

Question 25

What is the difference between gram positive and gram negative bacteria?

Answer 25

GP bacteria contain a peptidoglycan wall which is really polar, so GP are really hydrophilic. 90% of GP membrane is made of peptidoglycan, only 10% in GN membrane. The second layer of GN is made of lipids so it is amphipathic in nature. Endotoxins are released via GN, Exotoxins from GP.
GP don’t decolourise from staining, GN do.

Question 26

How can antibiotic processes be inhibited?

Answer 26

Plasmids which contain a bacteria’s DNA can have horizontal gene transfer, not just vertical gene transfer, so mutations within generations.