PMI03-2012 Acute Inflammation

Question 1

What is acute inflammation?

Answer 1

The initial response taking place in the minutes and hours following injury

Question 2

What is chronic inflammation?

Answer 2

Persistent inflammation taking place alongside attempts at healing

Question 3

What are the functions of acute inflammation?

Answer 3

Carriage of fluid, proteins and cells from local blood vessels to damaged areas
Destruction of the causative agent driving the inflammation through the dilution of toxins and entry of leukocytes
Removal of damaged tissue from the site and initiation of repair
Initiation of repair through fibrin formation and transport of nutrients and drugs

Question 4

What are the two events of the vascular phase?

Answer 4

Vasodilation and increased Vascular permeability

Question 5

What process initiates acute inflammation?

Answer 5

vasodilation

Question 6

What occurs during the vasodilation process?

Answer 6

Vasodilation results form the direct action of smooth muscle cells and endothelial cells
Due to tissue damage, histamine, prostaglandins, platelet activating factor and kinins are released

Question 7

How does vasodilation affect the flow rate?

Answer 7

Decreases the flow rate, causing vascular congestion

This leads to heat, redness, swelling and pain at the site of injury

Question 8

What are the effects of increased vascular permeability?

Answer 8

There are gaps between the endothelial cells opening, which results in the leakage of fluid and plasma proteins into the extra vascular space

Question 9

How does increased vascular permeability arise?

Answer 9

Due to the release of histamine, leukotrienes, platelet activating factors and kinins

Question 10

What is exudation?

Answer 10

The process by which there is net flow of fluid and plasma proteins from within the vessel into the EVS

Question 11

What is the fluid exudate?

Answer 11

The fluid that collects in the EVS

Question 12

What normally occurs in the EVS in terms of hydrostatic pressure?

Answer 12

There is increased hydrostatic pressure in the EVS at the venous end, which forces fluid back into the vessel and there is no net gain of fluid into the EVS

Question 13

What occurs during acute inflammation to the EVS?

Answer 13

There is increased vascular permeability at the venous end, which leads to increased osmotic pressure at the EVS so there is a net flow of fluid in the EVS resulting in fluid exudate

Question 14

What is margination?

Answer 14

At sites of inflammation, neutrophils are found towards the edges closer to the endothelial cells

Question 15

How do the neutrophils attach to the endothelial cells in acute inflammation?

Answer 15

As neutrophils marginate, they are able to detect ligands on endothelial cells
There is a weak bond between the selectins of neutrophils and endothelial cells
A process of attachment and detachment occurs
As a result, neutrophils roll across the endothelial surface in a process called rolling
Rolling ends when the neutrophil becomes firmly attached to the endothelial cell, which is brought about by the expression of integrins on the neutrophils which bind to ICAM-1 on the endothelial cell

Question 16

What group of receptors are important in the cellular events?

Answer 16

Selectins
P-selectin on endothelial cells
L-selectin on neutrophils

Question 17

What are the selectins upregulated by?

Answer 17

The selectin receptors are upregulated by IL-1 and TNF, which are expressed as a result of tissue damage

Question 18

What occurs after attachment of neutrophils to endothelial cells?

Answer 18

The neutrophil squeezes through the endothelial cell and into the fluid exudate
The neutrophils act as the cellular component of the fluid exudate
Once the neutrophils enter the fluid exudate, it migrates to the site where it is most needed by attraction by bacterial products, chemokine, C5a and leukotriene B4 in a process called chemotaxis

Question 19

How do neutrophils act?

Answer 19

Attachment and phagocytosis
Production of reactive oxygen intermediates (respiratory bursts)
Production of inflammatory mediators

Question 20

What is a respiratory burst?

Answer 20

A rapid release of reactive oxygen species by neutrophils and monocytes
These are released on contact with pathogens and are important in the degradation of internalised bacteria and fungi

Question 21

What are cardinal signs of inflammation?

Answer 21

Heat, redness, swelling, pain and loss of function

Question 22

What are the beneficial effects of acute inflammation?

Answer 22

Dilution of toxins
Entry of antibodies
Transport of drugs
Fibrin formation
Transport of nutrients

Question 23

What are the adverse effects of acute inflammation?

Answer 23

Tissue damage
Swelling
Pyrexia (fever)