Pathology - Inflammation

Question 1

What are the four inflammatory responses to injury?

Answer 1

Vascular Changes
Cellular Changes
Chemical Mediators
Morphological Patterns

Question 2

What vascular changes occur in response to injury?

Answer 2

Changes in flow and vessel calibre
Vasodilatation
First involves arterioles then capillary beds

Question 3

What mediates vascular changes?

Answer 3

Histamine and nitric oxide

Question 4

What is the result of vascular changes?

Answer 4

Increased heat (calor) 
Redness/erythema (rubor)

Question 5

What cellular changes occur in response to injury?

Answer 5

Stasis 
White cell margination 
Rolling 
Adhesions 
Migration

Question 6

What is white cell margination?

Answer 6

With vascular dilatation, blood flow slows down

Allows cells, especially large white cells, to move peripherally

Question 7

What are selectins?

Answer 7

Expressed on endothelial cell surface

Question 8

What are integrins?

Answer 8

Bind to vessels walls, cell matrix and other cells

Over 30 types

Question 9

Why does rolling occur?

Answer 9

Integrin/selectin interaction with their ligands is of low affinity and binding on and off are fast

Question 10

Which mediators increase selectin expression?

Answer 10

Histamine and thrombin from inflammatory cells

Question 11

What mediators increase endothelial cell expression of VCAM and ICAM?

Answer 11

Tumour necrosis factor

Interleukin-1

Question 12

What are VCAM and ICAM?

Answer 12

Vascular cell adhesion molecule

Intercellular adhesion molecule

Question 13

What increases the affinity of VCAMs and ICAMs for integrins?

Answer 13

Proteoglycans on endothelial cell surface (only when bound to chemokines from site of injury)

Question 14

What changes occur to vascular permeability?

Answer 14

Leaky vessels = loss of proteins
Change in osmotic pressure
Water follows protein = swelling (tumour)

Question 15

Why do vessels become so leaky?

Answer 15

Endothelial contraction - Histamine, bradykinin, substance P, leukotrienes
Direct injury - toxins, burns
White cells - attack vessel wall (self harm)
Transcytosis - VEGF mediated
New verse formation - VEGF makes new vessels and increases leakiness

Question 16

What is chemotaxis and which components act as “chemotaxis molecules”?

Answer 16

Cells follow a chemical gradient and move along it 
Bacteria components 
Complement 
Leukotrienes 
Cytokines - interleukins

Question 17

What are the three stages of phagocytosis?

Answer 17

Recognition and attachment
Engulfment
Killing and degradation

Question 18

How does recognition and attachment occur?

Answer 18

Mannose receptors
Bacteria contain terminal mannose residues; mammalian cells do not

Scavenger receptors

Opsonins
Coated with proteins, including compliment cascade components and IgG

Question 19

How does engulfment occur?

Answer 19

Pseudopods
Vesicle formation - phagosome
Joins with lysosome - phagolysosome

Question 20

How does killing and degradation occur?

Answer 20

Reactive oxygen species
NADPH oxidase

Reactive nitrogen species
Nitric oxide synthase

Question 21

What are the clinical features of acute inflmmation?

Answer 21

Rubor
Calor 
Tumor 
Dolor
Loss of function

Question 22

What causes rubor?

Answer 22

Redness

Increased perfusion, slow flow, increased vessel permeability

Question 23

What causes calor?

Answer 23

Heat

Increased perfusion, slow flow rate, increased vessel permeability

Question 24

What causes tumor?

Answer 24

Swelling

Vascular changes

Question 25

What causes dolor?

Answer 25

Pain | Mediated by prostaglandins and bradykinin

Question 26

What is the microscopic appearance of the neutrophil?

Answer 26

Moly lobed nucleus (polmorph) Granulocyte Phagocytic and cytotoxic abilities

Question 27

What is the main cell of acute inflammation?

Answer 27

Neutrophil

Question 28

What are the potential outcomes of acute inflammation?

Answer 28

Resolution Suppuration Repair, organisation and fibrosis Chronic inflammation

Question 29

What factors can influence the outcome of acute inflammation?

Answer 29

Site of injury Type of injury Duration of injury

Question 30

What is resolution?

Answer 30

Complete restoration of the tissue to normal after removal of inflammatory components

Question 31

What factors are needed for resolution to occur?

Answer 31

Minimal cell death Tissue has capacity to repair Good vascular supply Injurious agent easily removed

Question 32

What is suppuration?

Answer 32

Formation of pus

Question 33

What is pus?

Answer 33

Contains living, dying and dead cells | Neutrophils, bacteria and inflammatory debris

Question 34

Why is an abscess difficult to get rid of?

Answer 34

No blood supply reaches the middle, and so antibodies cannot get in

Question 35

What is an empyema?

Answer 35

Walled off space filled with pus

Question 36

What factors might result in organisation?

Answer 36

Injury with lots of necrosis Injury with lots of fibrin which isn't easily cleared Poor blood supply Tissue type Mucosa where damage goes beyond the basement membrane

Question 37

What is organisation?

Answer 37

Scarring

Question 38

What is an ulcer?

Answer 38

Erosion beyond the basement membrane

Question 39

What is granulation tissue?

Answer 39

Aids healing Defect is slowly infiltrated by capillaries and then myofibroblasts Deposit collagen and smooth muscle cells Looks very red Acts as a stop gap

Question 40

What is the main problem with scarring and fibrosis?

Answer 40

Loss of function | e.g. heart muscle that won't contract, or tight skin

Question 41

When might chronic inflammation be favoured?

Answer 41

Suppuration, empyema, scarring Persistence of injury - foreign material Infectious agent - virus, persistent (mycobacterium) Type fo injury - autoimmune, transplant injury

Question 42

What cells characterise chronic inflammation?

Answer 42

Lymphocytes and macrophages

Question 43

What might cause granuloma formation?

Answer 43

``` Foreign bodies = Endogenous (e.g. keratin) or exogenous (e.g. asbestos) Specific infections Parasites Worms, eggs Syphilis Mycobacterium ```

Question 44

What is a granuloma?

Answer 44

Aggregate of epthelioid histiocytes

Question 45

What granuloma is seen in TB?

Answer 45

Caseous necrosis