(W3) Acute Inflammation

Question 1

What are the benefits of inflammation, how can it be harmful and what are the cardinal signs of it?

Answer 1

Benefits:

• get rid of damaged or necrotic tissue
• remove microorganisms or other foreign material
• sets the scene for regeneration or repair of tissues (need inflammation for healing)

Harmful:

• hypersensitivities e.g. pollen
• autoimmune reactions
• prolonged inflammation (chronic)

Signs:

• redness (rubor)
• swelling (tumor)
• heat (calor)
• (pain) (dolor)
• loss of function (functio laesa)

Question 2

What are the 3 components of the physiological response to a stimuli (inflammation)?

Answer 2

• increased blood flow (when tissue is inflamed, arteriole and venule dilate , which bring heat and redness)
• increased vascular permeability (more fluid can leak out so causes oedema - swelling)
• leukocyte emigration (out of blood and into tissues)

Question 3

What are the 5 stimuli for acute inflammation?

Answer 3

Microorganisms:

• parasites, fungi, bacteria and viruses
• microbial toxins
• receptors e.g. Toll-like receptors (TLRs) and cytoplasmic receptors

Necrosis:

• ischaemia, trauma, physical and chemical injury
• molecules released from necrotic cells (e.g. ATP/DNA/uric acid/HMGB-1 outside of cells are proinflammatory

Hypoxia:

• Hypoxia-induced factor 1α (HIF-1α) (bind to endothelium and induces VEGF…)
• Induces vascular endothelial growth factor (VEGF) – increases vascular permeability

Foreign Bodies:
- cause trauma or carry microbes

Hypersensitivity reactions/AID

• self antigens
• excessive reactions to environmental/microbial antigens
• reactions where immune system damages own tissue

Question 4

What is oedema?

Answer 4

the release of excess fluid into tissue or body cavities

a type of transudate

Question 5

What is exudation?

Answer 5

the release of fluid and cells from the circulation

Question 6

What is an exudate? What is a purulent exudate?

Answer 6

an extracellular fluid rich in protein and containing cells

• has high specific gravity

Purulent exudate:
- rich in leukocytes (mainly neutrophils), debris of dead cells +/- microbes

Question 7

What is a transudate and what causes them to be formed?

Answer 7

fluid with low protein content and little or no cellular material (has low specific gravity)

• it is an ultrafiltrate of plasma (no increased vascular permeability) caused by loss of osmotic pressure or high hydrostatic pressure

Question 8

What are the 3 ways in which the blood vessels react to inflammation?

Answer 8

• vasodilation (there is a few seconds of vasoconstriction prior to vasodilation though)
• increased vascular permeability
• stasis