Pathology Flashcards
(256 cards)
What are the main cells associated with acute and chronic inflammation?
Acute - Neutrophils
Chronic - Macrophages & lymphocytes
Are local and systemic signs more prominent in acute or chronic inflammation?
Acute
Is tissue injury and fibrosis usually milder in acute or chronic inflammation?
Acute
*Chronic can be progressive
What are the responses to injury resulting in acute inflammation?
Vascular and cellular changes
Which vessel dilates first in acute inflammation? What dilates after that? Which 2 mediators are involved in this?
Arterioles –> pre-capillary sphincter –> capillary beds
Histamine and NO.
What happens to the microvasculature during acute inflammation?
Becomes more permeable, allowing exudation to occur thus slowing blood flow –> increased viscosity –> stasis, engorgement and white cell margination/ pavementing (redistribution)
What are the 6 processes involved in cellular changes of acute inflammation?
Stasis White cell margination/ pavementing Rolling Adhesion Migration via diapedesis Chemotaxi
Histamine and thrombin released from inflammatory cells can activate endothelium, resulting in the expression of?
Selectin (adhesion molecules)
How strongly does selectin bind to WBCs? What movement does this result in?
Low/ weak affinity causing a rolling movement
What happens when WBCs encounter chemokines?
Changes conformation and expresses integrin which binds at high affinity to VCAM ad ICAM at endothelium
What causes endothelium to express ICAM and VCAM?
Cytokines (TNF, IL-1)
Where and how do WBCs migrate to the extravascular space? What is this process called?
At post-capillary venules (maximal retraction), WBCs migrate by squeezing though intercellular junction.
Transmigration/ extravasation.
Where and how do leukocytes migrate in the extravascular space?
What is this process called?
Front wheel motion towards stimulus where chemoattractants were produced.
Chemotaxi.
What causes swelling/ oedema?
Decreased vascular permeability causing loss of protein and oncotic pressure –> water leaves
What are the 4 causes of vascular leakiness
- Endothelial retraction from mediators (short-lived at post-capillary venule)
- Endothelial injury resulting in necrosis and detachment
- Transcytosis - increased fluid and protein transport
- Angiogenesis - via VEGF (initially leaky e.g. granulation tissue)
What are the 3 components of phagocytosis?
- Recognition and attachment via mannose receptors (microbes), scavenger receptors (OxLDL) and opsonins
- Engulfment via pseudopods and phagosome formation
- Killing and degradation in lysosome via ROS (NADPH oxidase), RNS (NO synthease) and lysosomal enzymes
Why can phagocyte engulfment cause bystander damage?
Due to granule release into extracellular space
What mediates pain felt in inflammation?
Prostaglandins and bradykinins
What are the 4 mediators for endothelial retraction?
Histamine, Bradykinin, Substance P, Leukotrienes
How long do neutrophils live after leaving the blood before undergoing apoptosis?
A few hours to a day (short-lived)
What are the 4 possible outcomes of acute inflammation?
- Resolution
- Suppuration
- Repair, organisation and fibrosis
- Chronic inflammation
**All 2-4 are not mutually exclusive
What do the outcomes of acute inflammation depend on?
- Site of injury (E.g. capacity of organ to repair)
- Type of injury (E.g. pathogenicity)
- Duration of injury
What the term for when there is complete restoration of tissue function to normal after removal of inflammatory components called?
How long do injuries usually last for this?
Resolution.
Short-lived injury with minimal tissue destruction.
An example of an injury that leads to resolution
Erosions/ abrasions (with intact basement membrane)