Introduction To Inflammation

Question 1

What is inflammation?

Answer 1

The body’s immediate response to injury (part of innate non-specific immunity)
It is designed to rid the body of initial cause of injury and break down cells damaged by injury by bringing cells to the site of the insult.
It is not a disease but a protective response.

Question 2

What suffix denotes inflammation?

Answer 2

Itis

Question 3

What are the beneficial effects of inflammation?

Answer 3

Delivery of immune cells and proteins
Dilution of toxins (that caused injury)
Eliminate substance and repair tissue
OR Stimulate further more specific immune response
Entry of drugs - we can exploit the flow of blood to the area as more drug will go to that specific area

Question 4

How can inflammation go wrong?

Answer 4

Excessive/inappropriate inflammation can destruct normal tissue, cause swelling and pain & block tubes
Can be inappropriately triggered e.g. arthritis
Inadequate inflammation for e.g. in AIDs patients can get other conditions (e.g. pneumonia) as a result of lowered immunity

Question 5

List some of the causes of inflammation.

Answer 5

Burns
Physical damage/trauma/injury
Infection e.g. viruses, bacteria, parasites
Autoimmunity/autoantigens
Drugs
Chemicals
Allergy/hypersensitivity 
Stress
Toxins

Question 6

What is the definition of acute inflammation?

Answer 6

The immediate defensive reaction of tissue to injury, in which vascular and exudative processes predominate. Can last hrs, days or wks.

Question 7

What are the 5 macroscopic features of acute inflammation?

Answer 7

1. Erythema (redness)
2. Oedema (swelling)
3. Warmth
4. Pain
5. Loss of function

Question 8

What are the microscopic features of acute inflammation?

Answer 8

Vascular changes: vasodilation and increased permeability -> macroscopic features
Exudative changes: fluid & proteins and emigration of leukocytes/WBCs -> move from vasculature to the problematic tissue

Question 9

What do leukocytes/WBCs do in acute inflammation?

Answer 9

Neutrophils are the main cell type involved and they will perform phagocytosis - they will recognise a foreign body -> take it into the cell -> engulf it into a phagosome -> joins with a lysosome -> enzymes in the lysosome will break it down destroying it -> debris released from cell

Question 10

What are the outcomes of acute inflammation, and what determines them?

Answer 10

The nature of the stimulus and effectiveness of response (affected by age, nutrition, stress, co-morbidities, smoking, prior exposure etc.) will determine the outcome which can be acute. This can be resolved or become chronic. Chronic inflammation can also get resolved or it can lead to scarring.

Question 11

What happens in healthy tissue injury in acute inflammation?

Answer 11

Cross fire can occur in process of resolving injury as enzymes are not specific so can affect nearby tissues via:
Lytic enzymes
Accumulation of pus
Autoimmunity
This is the consequence of a response to a pathogen going wrong

Question 12

What is the definition of chronic inflammation?

Answer 12

Prolonged and persistent inflammation; which may be a continuation of acute inflammation (body has not been able to deal with insult), or the result of an insidious insult, characterised by scar tissue formation.
Prolonged duration - wks, mnths, yrs
Inflammation, injury and repair co-exist in varying amounts

Question 13

What are the causes of chronic inflammation?

Answer 13

Persisting infection e.g. TB, viral hepaptitis
Autoimmunity e.g. Crohn’s, RA
Persistent foreign material e.g. suture material, asbestos
Inadequate immune response e.g. in AIDs
Persisting trauma e.g. inadequate blood supply with vascular disease, bed sores in bed bound patients

Question 14

What are the macroscopic features of chronic inflammation?

Answer 14

Evidence of tissue destruction i.e. necrosis

Attempt at repair causes fibrosis which leads to loss of function

Question 15

What are the microscopic features of chronic inflammation?

Answer 15

New leukocytes/WBCs are involved such as lymphocytes & macrophages and eosinophils & basophils
Adaptive specialised immunity is involved

Question 16

What are the 2 types of lymphocytes and what do they do?

Answer 16

T lymphocytes are split into T helper cells and cytotoxic T cells. T helper cells secrete cytokines that direct other cells to site of injury whereas cytotoxic T cells kill foreign cells. T cells mature in the thymus.
B cells/plasma cells secrete antibodies which can bind microorganisms and tag them for destruction by other immune cells. Mature in bone.

Question 17

What is leukocytosis and how can the type of WBC in bloods help you determine what type of infection a patient is experiencing?

Answer 17

Leukocytosis = raised WBCs
Raised lymphocytes - viral
Raised eosinophils - parasitic
Raises basophils - allergy

Question 18

What are the other mediators of the immune system?

Answer 18

Monocytes/macrophages - monocytes become phagocytic macrophages when they go from the circulation into tissues
Interleukins - cause fever
Acute phase proteins - e.g. CRP (acute), ESR (chronic)
Complement - help immune system to recognise foreign material

Question 19

What are the 4 patterns of chronic inflammation?

Answer 19

Granulomas
Ulcers
Serous & fibrinous
Suppuration

Question 20

What is granulomatous inflammation?

Answer 20

Chronic inflammation where neutrophils could not phagocytose and deal with insult
Granulomas = collections of macrophages
E.G. mycobacteria (TB), foreign material (suture material), some fungi and sarcoidosis
Characteristic appearance - necrotic centre (dead cells), surrounded by macrophages (remnants of digested contents surrounding too), then T & B cells

Question 21

What are ulcers?

Answer 21

Break in epithelial surface
Can occur in acute or chronic
E.G. aphthous ulcers, peptic ulcers and ulcerative colitis

Question 22

What is the characteristic appearance of a chronic ulcer?

Answer 22

The ulcer will be on the mucosa at the surface
The submucosa layer will have acute inflammatory exudate, vascular granulation tissue and fibrovascular granulation tissue in it
Muscle will show fibrous scarring underneath

Question 23

What is serous and fibrinous inflammation?

Answer 23

Accumulation of fluid
Acute - serous = vasodilation and leaky vessels go wrong -> fluid accumulation in pockets of damaged tissue/body cavities)-> blister
Chronic - fibrinous = fluid cannot go anywhere so it collects -> scar tissue and adhesions

Question 24

What is supparation?

Answer 24

Acute or chronic
Accumulation of pus i.e. neutrophils
Persistent organism or foreign body
E.G. abscess, empyema

Question 25

What are the possible outcomes of chronic inflammation?

Answer 25

Ongoing inflammation
Change in tissue function e.g. atrophy, metaplasia
Repair and return if insult removed
Dysfunction and scarring
Catastrophe (even death e.g. ulcer going deeper and then perforating tissues)

Question 26

What are the macroscopic and microscopic features of Crohn’s disease (IBD)?

Answer 26

Macroscopic:
Affects anywhere (mouth -> anus)
May not be continuous
Bowel thickened, narrow with ulcers & fissures giving cobblestone appearance
Fistulae i.e. route between 2 epithelium surfaces
Abscesses

Microscopic:
Transmural inflammation i.e. all the way through thickness of bowel
Patchy, skip lesions 
Chronic inflammatory cells predominate
Granulomas

Question 27

What are the macroscopic and microscopic features of ulcerative colitis (IBD)?

Answer 27

Macroscopic: 
Colon only
Continuous 
Mucosa red, inflamed and bleeds easily
Ulceration
Polyps

Microscopic:
Chronic inflammatory cell infiltrate
Abscesses