Introduction to inflammation Flashcards
List the signs and symptoms of inflammation
- Heat
- Swelling
- Pain
- Erythema
- Loss of function
What is the definition of inflammation?
What is its purpose?
What part of the immune system is it part of?
The body’s immediate defensive response to an insult or injury.
Designed to:
- Rid the body of the initial cause of injury
- Break down cells damaged by injury
Part of innate immunity
What are the beneficial effects of inflammation?
- Allows delivery of immune cells and proteins to site of insult/injury
- Dilution of toxins
- Eliminate substance and repair of tissue OR stimulate further immune response
- Entry of drugs (increased blood supply to area)
What are the causes of inflammation?
- Infection
- Physical trauma
- Chemicals
- Dead cells
- Foreign bodies
- Allergens
Define acute inflammation
The body’s immediate defensive reaction of a tissue to injury, in which vascular and exudative processes predominate.
What are the macroscopic features of acute inflammation?
Heat
Swelling
Loss of function
Pain
Erythema
What are the microscopic features of acute inflammation?
- Vascular changes:
- Vasodilation
- Increased permeability of blood vessels
- Leads to erythema, warmth and oedema which leads to pain and loss of function.
- Exudative changes:
- Fluid and protein leakage
- Emigration of leukocytes
Which leukocyte predominates usually in acute infection?
Neutrophils
What is the role of leukocytes?
Phagocytosis (of any substance identified as non-self)
- Identifies substance
- Engulfs it into a phagosome
- Phagosome joints with a lysosome which contains lytic enzymes that break down the substance
- Remaining debris releasd from the cell through exocytosis
What are the possible outcomes of acute inflammation?
- Resolution
- Chronic inflammation:
- → resolution OR
- → scarring
- Injury of nearby healthy tissues
- Lytic enzymes are not specific to insulting substances
- Accumulation of pus
- Autoimmunity (can be triggered from a response to a pathogen)
Define chronic inflammation
Prolonged and persistent inflammation which may be a continuation of acute inflammation or the result of an insidious insult, characterised by scar tissue formation
What are the causes of chronic inflammation?
Give examples for each
Persisting (unresolved) acute infection:
- Immunodeficiency/suppression, e.g. AIDS
- Persistant infection, e.g. TB
Autoimmunity, e.g. crohn’s disease
Persisting trauma, e.g. pressure sores
Persisting foreign bodies, e.g. asbestos
Describe the macroscopic features of chronic inflammation
Combination of injury, repair and inflammation that co-exist
Describe the microscopic features of chronic inflammation
New leukocytes:
- Lymphocytes: T-lymphocytes (TH and TC) and B cells
- Macrophages
- Eosinophils and basophils
What are the roles of TH and TC lymphocytes?
Where do they originate from?
Develop in the thymus
TH: secrete cytokines which direct other immune cells to the affected area.
TC: destroy the infecting organism by stimulating cell death.
What are the roles of B-cells?
Where do they originate from?
Originate from bone
Secrete antibodies that bind to micro-organism, identifying it for destruction by other immune cells
Define leukocytosis
What can be seen on the blood results of someone with:
Acute infection
Chronic/viral infection
Parasitic infection
Allergic reaction
Leukocytosis = high WCC
- Acute infection = high neutrophil count
- Chronic/viral infection = high lymphocyte count
- Parasitic infection = high eosinophil count
- Allergic reaction = high basophil count
What other mediators are involved in inflammation aside from neutrophils, lymphocytes, eosinophils and basophils?
Interleukins
Monocytes/macrophages
Acute phase proteins (CRP, ESR)
Complement
Describe a granulomatous pattern of inflammation?
When can this be seen?
Granuloma = collection of macrophages
Can be seen in:
- TB
- Foreign material
- Fungi
- Sarcoidosis
What is an ulcer? Describe what can be seen in a chronic ulcer
What is an example of an acute ulcer?
Ulcers= break in epithelial lined surface
Acute ulcers: e.g. apthous
Chronic ulcers:
- Acute inflammatory exudate
- Vascular granulation tissue
- Fibrovascular granulation tissue
- Fibrous scar
Describe a serous and fibrinous pattern of inflammation
Give examples of each
Accummulation of fluid caused by vasodilation and increased vascular permeability allowing fluid to leak into spaces created by injury or body cavities.
Acute: serous, e.g. blister
Chronic: fibrinous, e.g. pericardial effusion
What is suppuration?
Pus
From persistent organism or foreign body, e.g. abscess, empyema
What are the possible outcomes of chronic inflammation?
- Resolution if damaging stimulus removed
- Change in function of the affected organ/tissue:
- Atrophy
- Metaplasia
- Scarring and dysfunction, e.g. cirrhosis (viral hepatitis)
What is Crohn’s disease?
Inflammatory bowel disease that can affect anywhere in the GI tract from the mouth to the anus. Characterised by inflammation.
What are the macroscopic features of Crohn’s disease?
Thickenings and narrowings of bowel- cobblestone appearance
Fistulae
Abscesses
What are the microscopic features of Crohn’s disease?
Transmural inflammaiton
Patchy, skip lesions
Granulomas
Chronic inflammatory cells predominate
What is ulcerative colitis?
Inflammatory bowel disease affecting the colon only.
What are the macroscopic features of ulcerative colitis?
Red, inflamed mucosa that bleeds easily
Ulceration
Polyps
What are the microscopic features of ulcerative colitis?
Abscesses
Infiltration of chronic inflammatory cells
