7.1.1 Acute Inflammation

Question 1

What are the 5 cardinal signs of inflammation?

Answer 1

• reddening (↑ bloodflow)
• swelling (exudation of fluid from dilated vessels)
• increased heat (↑ bloodflow)
• pain (chemical mediators, pressure on nerves)
• loss of function (reluctant use / lameness)

Question 2

What are the four main causes of inflammation?

Answer 2

Microorganism and parasites

Trauma

Aberrant immune system

Malignant neoplasms

Question 3

Describe acute inflammation

Answer 3

Sudden onset, lasts hours to days

Vascular, humoural and cellular alterations cause the 5 cardinal signs

Question 4

Describe sequelae inflammation

Answer 4

1 - death
2 - resolve by regeneration with host defence mechanisms (tissue replaced by scar tissue)
3 - undergo repair by fibrosis
4 - become chronic

Question 5

Describe acute inflammation stage 1: vascular phase

Answer 5

1 - Initial phase = transient, arteriole constriction, smooth muscle response

2 - Hyperaemia = arteriole and capillary dilation, chemical mediators open precapillary sphyncters

Question 6

Describe acute inflammation stage 2: Exudative phase

Answer 6

Endothelial cell contraction = ↑ vascular permeability

Escape of protein-rich fluid from blood into surrounding tissues

Question 7

Describe acute inflammation stage 3: Migration of leucocytes

Answer 7

Margination / pavementing
- altered bloodflow, loss of axial stream
- adhesion molecule expression

Chemotaxis
- neutrophils, macrophages
- chemotaxins attract/activate laukocytes

Emigration via intracellular junctions
- motile cells force an opening
- basement membrane is breached

Question 8

Describe the roles of NEUTROPHILS in acute inflammation

Answer 8

Phagocytosis, fusion of phagosomes and lysosomes

Secretion into exudate to enhance acute inflammatory response

Loosely stick and role along venules and capillaries, migrate out at junctions between endothelial cells, travel to site of damage

Question 9

Describe the roles of EOSINOPHILS in acute inflammation

Answer 9

Parasitic infections and local allergic reactions (IgE)

Question 10

Describe the roles of MAST CELLS in acute inflammation

Answer 10

Degranulate in tissue injury

Release histamine, heparin, serotonin (chemical mediators of vasodilation, chemotaxis, pain

Critical in initiation of acute inflammatory response

Question 11

Describe the roles of BASOPHILS in acute inflammation

Answer 11

Important in IgE mediated injury to tissues (allergic reactions)

Question 12

What is pyrexia?

Answer 12

Pyrogens act on temp control centres (hypothalamus) to raise body temp

Pyrogens release from:
- neutrophils, eosinophils, macrophages (phagocytosis)
- Gram -ve organisms (cell walls contain pyrogens)
- Damaged tissue cells (necrosis releases pyrogens)
- Antigen-antibody complexes (release pyrogens)
- Tumours (release pyrogens - esp. if metastasised)

Question 13

What are the 6 functions of inflammatory effusion?

Answer 13

1 - dilutes toxic agent
2 - protein components contain antibodies (IgG)
3 - contain fibrin to immobilise irritant, framework
4 - chemotactic to neutrophils
5 - wash away irritant
6 - bring irritant via lymphatic vessels to lymph nodes for further processing or presentation

Question 14

What are the 6 classifications of inflammation by fluid type (effusion)

Answer 14

1 - Serous (fluid-filled vesicles)
2 - Catarrhal (goblet cells/mucous glands)
3 - Fibrinous (escape of fibrinogen = fibrin)
4 - Diphtheritic (fibrinous exudate w/ necrosis)
5 - Haemorrhagic (in LNs, lungs, intestines)
6 - Purulent (pus and abscess formation)

Question 15

Deleterious effects of inflammation

Answer 15

• Local tissue swelling
• Local tissue damage (due to inflammatory cells)