Inflammation Flashcards
Inflammation - definition
Dynamic process by which living tissues react to injury
usually vascular and connective tissue
Inflammation - process
injured cells release substances into the damaged area and bloodstream
attracts WBC and causes vessel dilation
Gaps appear in endothelial cells lining blood vessels
Allow plasma leakage into injured tissue introducing protein and molecules to influence reaction
Injury dependent - tissue swells with fluid and blood, distends and becomes red,warm and painful
Causes of Inflammation
same as causes of disease
Inflammation - hallmarks
PRISH
Pain (dolor) Redness (rubor) Immobility (Loss of function) Swelling Heat
Inflammation - features
Hyperaemia
Vascular changes
Oedema and Leukocyte migration
Inflammatory Exudates
Inflammation - Hyperaemia
Microvascular changes results in:
Flush - red spot (capillary dilation)
Flare - redness of surrounding tissue (arteiolar dilation mediated by axon reflex)
Wheal - due to exudation of fluid from capillaries and venules
Vasodilation after injury (Histamine, PGI2 and NO)
Increased hydrostatic pressure = slower bloodflow
Margination of leukocytes occur (WBC to vessel wall)
Inflammation - Vascular changes
Vasodilation and vascular permeability increases due to Histamine, Leukotrienes C4.D4 and E4
Plasma leakage results
Neutrophils adhere to capillary walls and move towards injury site
Increased vascular permeability results in:
1. Fluid movement across interstitial tissue (increase protein in interstitial tissue)
2. Reduction in plasma osmotic pressure
3. Increased interstitial osmotic pressure
Finally results in increased filtration pressure, fluid leaves vessels and causes local swelling (oedema)
Inflammation - Oedema and Leukocyte accumulation
WBC move into interstitial tissue in 4 steps:
- Rolling - irregular loose contact of WBC with endothelium due to margination
- Pavementing - regular tight contact of WBC with endothelium
- Transmigration - crossing of WBC through endothelial layer
- Chemotaxis - WBC drawn to inflamm site
Inflammation - Inflammatory Exudates
Combination of oedema and inflamm cells at site of injury
Neutrophil accumulation can be sparse or dense depending on severity - 3 types:
1. Serous (watery with low protein -mild/acute eg burns)
2. Fibrinous (high protein content - severe = scabs)
3. Supparative/Purulent (high neutrophils + necrotic debris = severe acute injury + bacteria)
Inflammation - Outcomes
Resolution (aided by min cell death)
Suppuration (abscess = bact +)
Ulcer (mucosa loss)
Fistula (abn passage )
Chronic Inflammation (persistent injury - homeostatic imbalance)
Fibrosis (lost parenchyma replaced with disorganised connective tissue)
Fistula
an abnormal or surgically made passage between a hollow or tubular organ and the body surface, or between two hollow or tubular organs.
Parenchymal cells
The parenchyma are the functional parts of an organ in the body. This is in contrast to the stroma, which refers to the structural tissue of organs, namely, the connective tissues.
Inflammation: Acute
Initial stage Sudden onset Shorter duration Typically exudate + leucocyte migration More severe signs + symptoms
Inflammation : Chronic
Follows acute (but can be primary)
Lymphocyte, macrophage + micro neovasc
Leads to Fibrosis (fibroblasts + collagen production)
Macrophage
(Greek: big eaters, from Greek μακρος (makros) = large, φαγειν (phagein) = to eat are a type of white blood cell that engulfs and digests cellular debris, foreign substances, microbes, cancer cells, and anything else that does not have the types of proteins specific of healthy body cells on its surface in a process called phagocytosis.
