Acute Inflammation

Question 1

What are the principle causes of acute inflammation?

Answer 1

1. Microbial infection
2. Hypersensitivity reactions
3. Physical agents
4. Chemical agents

Question 2

What are physical characteristics of acute inflammation?

Answer 2

+ Red (rubor)
- dilation of blood vessels

+ Hot (calor)

• peripheral increase in temperature
• due to increased blood flow (hyperaemia)

+ Swollen (tumor)

• due mainly to oedema
• some contribution from inflammatory cells

+ Painful/tender (dolor)
- stimulation of nerve endings by pressure and chemical mediators

+ Loss of function

Question 3

What is the vascular phase of acute inflammation?

Answer 3

Dilation and increased permeability of vessels

Question 4

What is the exudative phase of acute inflammation?

Answer 4

Fluid and cells escape from permeable venules

Question 5

What are the features of an exudate?

Answer 5

+ High protein content

+ Proteins include immunoglobulins
- may be important for destruction of invading organisms

+ Fibrinogen > fibrin

• on extravascular contact
• acutely inflamed organ surfaces commonly covered by fibrin

+ High turnover
- continuously removed via lymphatics

Question 6

Describe the capillaries during acute inflammation

Answer 6

\+ Open pre-capillary sphincter
\+ Dilation of the arterioles
\+ Dilation of the venules
\+ Most capillaries full
\+ Net flow out

Question 7

What are features of increased vascular permeability?

Answer 7

+ Produced by chemical mediators including histamine, bradykinin

+ Involves stimulation of endothelial cell cytoskeleton by chemical mediators

+ Confined to post capillary venules

+ Transient, intercellular gaps appear

+ Endothelial cells are not damaged in this way

Question 8

What are the 4 enzymatic cascade systems of

Answer 8

1. Complement system
2. The Kinin System
3. Coagulation factors
4. Fibrinolytic system

Question 9

What are the beneficial effects of acute inflammation?

Answer 9

DILUTION OF TOXINS: allows them to be carried away by lymphatics

ENTRY OF ANTIBODIES: due to increased vascular permeability

FIBRIN FORMATION: impedes movement of microorganisms

TRANSPORT OF DRUGS: e.g antibiotics

DELIVERY OF NUTRIENTS AND OXYGEN: aided by increased fluid flow

STIMULATION OF IMMUNE RESPONSE: fluid exudate containing antigens reaches local lymph nodes

Question 10

What are the harmful effects of acute inflammation?

Answer 10

+ Digestion of normal tissues

+ Swelling e.g laryngeal oedema, brain swelling

+ Inappropriate inflammatory response e.g type I hypersensitivity

Question 11

What are the systemic effects of acute inflammation?

Answer 11

+ Constitutional symptoms include malaise, anorexia, nausea

+ Weight loss due to negative nitrogen balance, particularly when there is extensive chronic inflammation

+ Reactive hyperplasia of the reticuloendothelial system

+ Haematological changes

+ Increases erythrocyte sedimentation rate

• anaemia
• leucocytosis