Inflammation Flashcards
What is inflammation?
The local physiological response to noxious stimuli, such as: infection and/or tissue injury. Manifestation of disease, not a disease.
What is acute inflammation?
The initial response to noxious stimuli.
List 4 features of acute inflammation.
1) sudden onset
2) short duration
3) usually resolves
4) neutrophils are the main cell involved
List 6 causes of acute inflammation.
1) microbial infection
2) bacterial toxins
3) tissue necrosis
4) hypersensitivity reaction
5) physical agents, e.g. trauma or temperature
6) chemical agents, e.g. corrosives or reducing agents
List 3 processes of acute inflammation.
1) increased vascular diameter
2) increased vascular permeability
3) formation of cellular exudate
List 4 outcomes of acute inflammation.
1) resolution (usual result) 2) suppuration (pus formation) 3) repair and reorganisation (necrosed tissue --> granulation tissue) (excess necrosis) 4) chronic inflammation (persistence of stimuli)
What happens during reorganisation? (4)
1) macrophages phagocytose dead tissue and acute inflammatory exudate
2) granulation tissue (vascular connective tissue) fills the damage site
3) fibroblasts in granulation tissue produce collagen
4) fibrous scar tissue forms
What is chronic inflammation?
Long term inflammation.
List 4 causes of chronic inflammation.
1) primary chronic inflammation
2) progression of acute inflammation
3) recurrent acute inflammation
4) transplant rejection
List 4 features of chronic inflammation.
1) slow onset / progression of acute inflammation
2) long duration
3) may never resolve
4) macrophages, lymphocytes and plasma cells are the main cells involved
List 3 functions of neutrophils.
Involved in acute inflammation.
1) phagocytic
2) secrete granules
3) secrete cytokines
List 2 functions of macrophages.
Involved in chronic inflammation.
1) phagocytic
2) antigen presentation
List 3 things macrophages phagocytose.
1) inflammatory exudate
2) damaged cells
3) necrosed cells
List 2 functions of B lymphocytes.
1) antigen presentation
2) secrete antibodies - plasma cells
What is the function of helper T lymphocytes?
Release cytokines to recruit and activate other immune cells.
List 3 functions of endothelial cells.
1) become sticky to allow inflammatory cells to adhere
2) become porous to allow inflammatory cells to pass into tissues
3) grow into areas of damage to form new capillary vessels
What is the function of fibroblasts.
Repair - synthesise collagen in inflamed areas - scarring.
What are epithelioid histiocytes?
Tissue-resident macrophages with specific features, e.g. Kuppfer cells
List 2 features of epitheliod histiocytes.
1) little phagocytic activity
2) adapted for secretion
What is a granuloma?
Collection of epithelioid histiocytes. May also contain lymphocytes and histiocytic giant cells.
How do histiocytic giant cells form?
Multiple epithelioid histiocytes trying to phagocytose the same large indigestible particulate, hence fusing into a multinucleate giant cell.
Define exudate.
Extravascular mass of cells and fluid due to increased vascular permeability.
What do exudate contain?
High protein content.
What do exudate result in?
Formation of oedema, hence swelling.
List the 5 features of inflammation.
1) calor - heat
2) dolor - pain
3) rubor - redness
4) tumor - swelling
5) loss of function
What is the cause of rubor?
Dilation of small blood vessels in inflamed area.
What is the cause of calor?
Vascular dilation, resulting in increased blood flow causes delivery of warm blood. Only seen in peripheries.
What is the cause of tumor?
Accumulation of extravascular fluid due to exudate forms an oedema.
List 2 causes of dolor?
1) inflammatory oedema causing stretching and distortion of tissue
2) chemical mediators of inflammation induce pain, e.g. prostaglandins, serotinin and bradykinin
List 2 causes of loss of function?
1) conscious and reflex inhibition of movement of inflamed area
2) severe swelling physically immobilises tissue
List the 2 main constituents of granulation tissue and their functions.
1) myofibroblasts (myocytes and fibroblasts) —> contract edges of wound and secrete collagen and extracellular matrix
2) capillary loops —> provide nutrients and leukocytes and take away cellular waste
When does resolution at inflammation site occur? (2)
1) initiating factor has been removed
2) tissue undamaged/able to regenerate
When does repair at inflammation site occur? (2)
1) initiating factor still present
2) tissue damaged/unable to regenerate
Define wound healing?
Skin repairs itself after damage.
List the 4 phases of wound healing.
1) haemostasis
2) inflammation
3) proliferation
4) maturation
Name the 2 types of wound healing.
1) healing by primary intention
2) healing by secondary intention
When does healing by primary intention occur?
When the wound is thin/tissue surfaces have been closed, e.g. stitches.
When does healing by secondary intention occur?
When the wound is large with considerable tissue loss.
Describe healing by primary intention. (5)
1) exudate contains fibrinogen
2) weak fibrin join forms
3) fibroblast synthesise collagen
4) strong collagen join forms
5) epidermis regrows
Describe healing by secondary intention. (5)
1) exudate contains fibrinogen
2) weak fibrin join forms
3) myofibroblast synthesise collagen
4) strong collagen join forms
5) myofibroblasts contract, decreasing space between dermal edges
6) epidermis regrows
List the 4 differences between healing by primary and secondary intention.
1) repair time
2) scarring
3) chances of infection
4) fibroblasts vs myofibroblasts
What occurs during repair?
Replacement of damaged tissue unable to regenerate with fibrous tissue.
List 2 cells that cannot regenerate?
1) myocardial cells
2) neurones (except peripheral nerves - slow rate of 1mm per day)
List 6 cells that can regenerate?
1) hepatocytes
2) pneumocytes
3) haemocytes
4) osteocytes
5) gut epithelium
6) skin epithelium
Increased plasma concentration of which enzyme is a marker for granulomatous disease?
Angiotensin converting enzyme.
