MoD 1

Question 1

What are the effector molecules of apoptosis called?

Answer 1

Caspases

Question 2

Which molecules are normally sequestered in mitochondria, but when released into the cytosol activate caspases?

Answer 2

Apoptosis initiating factor (AIF) and cytochrome C

Question 3

Why is the Erythrocyte sedimentation rate (ESR) faster during an acute phase reaction?

Answer 3

Erythrocytes are normally negatively charged and repel one another. When an inflammatory process is present there is an increase in the amount of fibrinogen in the blood, causing the erythrocytes to stick together and sink faster.

Question 4

What is found microscopically in acute inflammation?

Answer 4

Neutrophil polymorphs

Question 5

What is granulation tissue composed of?

Answer 5

Capillary loops and myofibroblasts

Question 6

What are the steps of neutrophil emigration?

Answer 6

Axial stream

• -> Margination into plasmatic zone
• -> Adhesion to endothelial cells (pavementing)
• -> Emigration as they pass through the basal lamina into the adventitia and surrounding tissue

Question 7

Which compliment factor binds to pathogens for opsonisation?

Answer 7

C3b

Question 8

Which compliment factors are mediators of inflammation, recruiting phagocytes?

Answer 8

C3a, C5a

Question 9

Which compliment factors form the membrane attack complex?

Answer 9

C5b, C6-C9

Question 10

What is the function of Natural Killer cells

Answer 10

Kill foreign and host cells that have low levels of class I MHC+ self peptides. Express NK receptors that inhibit NK function in the presence of high expression of self-MHC

Question 11

What are the primary lymphoid organs and what is their function

Answer 11

Bone marrow and Thymus, for lymphocyte development and selection

Question 12

What are the secondary lymphoid organs and their function

Answer 12

Spleen (white pulp), lymph nodes and mucosal surfaces, where the immune response occurs

Question 13

When foreign antigens are phagocytosed and broken down into peptides, what are they presented upon on the cell surface?

Answer 13

Class II MHC

These are recognised by CD4 helper T cells which become activated

Question 14

CD8 cytotoxic T cells detect antigens in association with which molecule

Answer 14

class I MHC

Question 15

What do CD8 cytotoxic T cells secrete when they detect foreign antigen on class I MHC

Answer 15

Perforin which punctures the membrane of the infected cell

Question 16

Th1 cells are effectors against which pathogens and active which kind of immune response

Answer 16

They are effectors against intracellular bacteria and protozoa. Triggered by IL- 2, Th1 cells promote a cellular immune response by secreting Interferon gamma (IFN-y) and IL-2. This stimulates macrophages and CD8 T cells

Question 17

Th2 cells are effectors against which pathogens and activate which kind of response

Answer 17

Th2 are effectors against extracellular parasites. Triggered by IL-4, Th2 cells promote a humoral response by secreting IL-4, IL-5, IL-9, IL-10, IL-13. This stimulates B cells, mast cells and eosinophils

Question 18

What are the main cytokines of the innate immune system?

Answer 18

TNF, IL-1, IL-6, IL-23

Question 19

Describe Hypersensitivity reaction type I

Answer 19

IgE mediated reaction - anaphylactic
Initial response = degranulation releasing histamine
Late phase reaction = synthesis of lipid mediators such as prostaglandins and leukotrienes from arachidonic acid. Cytokine production by activated T cells. Basophils and eosinophils degranulate.

Question 20

Describe Hypersensitivity reaction type II

Answer 20

Cytotoxic reaction - antibody mediated, eg blood group incompatibility

Question 21

Describe Hypersensitivity reaction type III

Answer 21

Immune complex reaction: antigen-antibody complexes are inadequately cleared by the body. These activate compliment causing the degranulation of basophils and neutrophils which damages the surrounding tissue

Question 22

Describe Hypersensitivity reaction type IV

Answer 22

Delayed type: T cell mediated reaction
Ag-specific T cells release cytokines - recruitment of macrophages (non Ag-specific)
Activated macrophages cause tissue damage

Question 23

Which inflammatory cells are most predominant in chronic inflammation?

Answer 23

mononuclear cells = macrophages, lymphocytes and plasma cells

Question 24

Why are macrophages important in chronic inflammation?

Answer 24

Stimulation of the immune system,
Phagocytosis of bacteria and damaged tissue,
Induce angiogenesis granulation tissue formation

Question 25

What is a granuloma

Answer 25

an aggregate of epithelioid histiocytes (macrophages in tissue)and other cells; lymphocytes and histiocytic giant cells.

Question 26

What is a histiocytic giant cell and how do they form?

Answer 26

They’re multinucleate giant cells, may have >100 nuclei. They form where material is indigestible to macrophages and 2+ macrophages try to engulf the same particle

Question 27

What is a Labile cell population?

Answer 27

High normal turnover
Active stem cell population
Excellent regenerative capacity
eg Epithelia

Question 28

What is a quiescent (stable) cell population?

Answer 28

Low physiological turnover
Turnover can massively increase if needed
Good regenerative capacity
eg liver, renal tubules

Question 29

What is a permanent cell population?

Answer 29

No physiological turnover
Long life cells
No regenerative capacity
eg neurons, muscle cells

Question 30

What causes a wound to heal by second intention?

Answer 30

The wound edges are not apposed so more granulation tissue forms

Question 31

Describe the process of bone fracture healing

Answer 31

Haematoma
Removal of necrotic fragments
Osteoblasts lay down woven bone forming a callus
Remodelling according to mechanical stress
Replacement by lamellar bone

Question 32

Describe the process of healing in the brain

Answer 32

Gliosis forms rather than scarring

Neurons are terminally differentiated
Supporting tissue is glial cells rather than myofibroblasts etc.
Hence damaged tissue is removed, often leaving cyst