Acute / Chronic inflammation

Question 1

Define Inflammation

Answer 1

Inflammation is the reaction of vascularised living tissue to local injury.

Mediated by the reaction of blood vessels to pro-inflammatory cytokines and chemokines, inflammation leads to the accumulation of fluid and immune cells at the site of infection.

Question 2

Define Repair

Answer 2

Repair is the replacement of injured tissue either by

1. Regeneration of parenchymal cells
2. Fibroblastic or Glial “scar” tissue

Question 3

Give 4 examples of where mechanisms of inflammation and repair can be harmful to the host.

Answer 3

Rheumatoid arthritis
Anaphylaxis
Renal disease (accumulation of immune complexes)
Fibrous adhesions (fibrous bands may cause twisting of the bowel and may cause complete occlusion)

Question 4

Define Exudate

Answer 4

Exudate is the term used to describe the inflammatory extravascular fluid that contains a high protein concentration and a S.G > 1020

Question 5

Define Transudate

Answer 5

An ultra filtrate with a low protein concentration - mostly albumin and a S.G

Question 6

Define Pus

Answer 6

A thick exudate rich in neutrophils and parenchymal cell debris.

Question 7

What are the 4 cardinal signs of inflammation?

Answer 7

Rubor - REDNESS
Tumour - SWELLING
Calor - HEAT
Dolor - PAIN

Question 8

What is meant by the “Triple Response” as termed by Sir Thomas Lewis in 1927?

Answer 8

Dull red line - Vasodilatation and increased blood flow
Surrounding flare
Wheal (Swelling of the stroke mark)

Question 9

What changes occur in the vascular flow and calibre following a hard stroke mark on the skin?

Answer 9

Transient vasoconstriction of arterioles causes a white line to appear briefly on the skin.

This is followed by prolonged vasodilatation and increased blood flow, creating a red line on the skin.

Slowing of the circulation due to increased permeability of the local microvasculature - “Stasis”.

Leucocyte margination and emigration.

Question 10

In chemotaxis, what are the receptor/surface molecule interactions between the endothelial cells and immune cells being recruited from the circulation?

Answer 10

Neutrophil LFA-1 to Endothelial cell ICAM-1
Lymphocyte VLA-4 to Endothelial cell VCAM
Leukocyte PSGL-1 to Endothelial cell E-selectin

Question 11

Since leukocytes continuously express cell adhesion molecules, what prevents unwanted chemotaxis?

Answer 11

Chemokine gradient draws leukocytes to the site of infection in order to satisfy their specific receptors for chemotactic agents.

Endothelial cells only upregulate the expression of cell adhesion molecules when there is inflammation. At rest, cell adhesion molecules such as P-Selectin are held in intracellular vacuoles called Weibel-palade bodies.
Histamine, thrombin and other pro-inflammatory triggers cause translocation of these W-P bodies to the cell’s surface to allow the cell adhesion molecules to be expressed.

Question 12

What are the 3 main chemotactic agents for neutrophils?

Answer 12

Leukocytes have specific receptors for the following chemotactic agents:

Bacterial products
Complement components such as C5a and C3a
Products of the lipoxygenase pathway of arachidonic acid metabolism - leukotriene B4

Question 13

What dominates in acute serous inflammation?

Answer 13

Mostly fluid, few cells

Question 14

What dominates in acute suppurative inflammation?

Answer 14

Mostly dead cells, little fluid

Question 15

What is inflammation of the lungs called?

Answer 15

Pneumonia

Question 16

What happens in acute membranous inflammation?

Give an example

Answer 16

Formation of an inflamed membrane over the tissue.
Pseudomembranous colitis caused by excessive antibiotic use, eliminating commensals in the gut, allowing Clostridium difficile to invade the tissue.

Question 17

The presence of what cells is usually an indicator of chronic inflammation?

Answer 17

Lymphocytes and Macrophages

Question 18

What is another sign of chronic inflammation?

Answer 18

Proliferation of fibroblasts and increased connective tissue - Fibrosis
Also the proliferation small blood vessels.

Question 19

True or False: Chronic inflammation can develop as a result of repeated bouts of acute inflammation

Answer 19

True
This may be caused by prolonged exposure to non-degradable substances, autoimmune diseases or persistent infections by intracellular organisms.

Question 20

What is a granuloma?

Answer 20

Granulomas are spherical collections of lymphocytes and macrophages that form at the area of injury.

If the cause of the inflammation is an infectious agent, then these granulomas are called Caseous Epithelioid Granulomas and the core of these granulomas undergoes necrosis.

If the cause of the inflammation is non-infectious (silica, paraffin oil, asbestos fibres or other foreign or inorganic material), then the granulomas are called Noncaseating Epithelioid Granulomas.

Both types of granulomas undergo healing by fibrosis.

Question 21

How are large foreign or inorganic particles dealt with?

Answer 21

The formation of giant, multinucleated cells that are comprised of many macrophages fusing together.

Once they become large enough, these cells can phagocytose the target particles.