Mediators of Inflammation Quiz

Mediators of Inflammation

• Mediators of inflammation are chemical substances that regulate inflammation.
• Two types exist: plasma-derived and cell-derived mediators.
• Plasma-derived mediators are proteins circulating in the blood, becoming active in response to inflammatory triggers. They are mainly produced in the liver.
• Cell-derived mediators are produced locally by cells.
• Most mediators are short-lived, breaking down quickly or being inactivated by enzymes.
• One mediator often triggers the release of another.
• Some mediators can harm cells and tissues.

Chemical Mediators

• Plasma-Derived:
  • Complement proteins (activated for inflammation)
  • Clotting factors
  • Kinin system
• Cell-Derived (Preformed):
  • Histamine (Mast cells)
  • Serotonin (Platelets and nerve endings)
• Cell-Derived (Synthesized de novo):
  • Arachidonic acid metabolites (e.g., prostaglandins, leukotrienes)
  • Cytokines (e.g., TNF, IL-1, IL-6)
  • Chemokines
  • Complement proteins (some)
  • Kinins

Actions of Mediators

• Histamine:
  • Source: Mast cells
  • Action: Vasodilation, increased vascular permeability.
• Platelet-activating factor: Affects blood vessels and platelets during inflammation.
• Cytokines:
  • Sources: Macrophages, mast cells, T lymphocytes, endothelial cells.
  • Actions: Involved in acute and chronic inflammation, fever, promoting leukocyte recruitment, and activating macrophages.
• Chemokines: Attract leukocytes to sites of inflammation.
• Complement:
  • Actions:
    • Opsonization (enhancing phagocytosis).
    • Chemotaxis (attracting leukocytes).
    • Cell lysis (membrane attack complex).

Arachidonic Acid Metabolites

• Derived from cell membrane phospholipids via the action of enzymes (e.g., phospholipases).
• Prostaglandins:
  • Actions: Vasodilation, increased vascular permeability, pain, fever.
• Leukotrienes:
  • Actions: Increased vascular permeability, bronchospasm, chemotaxis.
• Lipoxin:
  • Actions: Inhibit inflammation.

Types of Inflammation

• Acute Inflammation:
  • Characterized by vascular congestion, edema, and neutrophil infiltration.
  • Mediators include histamine, prostaglandins, leukotrienes, and cytokines.
• Chronic Inflammation:
  • Longer duration, involves mononuclear cells (lymphocytes and macrophages).
  • Mediators include cytokines and growth factors. Outcomes can be fibrosis.

Other types of inflammation

• Fibrous: Occurs when significant fluid leaks, clotting factors enter the tissues. Fibrin forms, and the tissues are scar-like.
• Serous: Characterized fluid accumulation and little cell debris, often in the body cavities.
• Purulent (suppurative): Pus formation, often caused by bacterial infection.
• Granulomatous: Collection of macrophages and lymphocytes, often a chronic response to something the body can't get rid of.
• Ulcers: Tissue loss, often in the lining of organs.

Test your knowledge on the mediators of inflammation, both plasma-derived and cell-derived. This quiz covers their roles, sources, and types, providing insights into how inflammation is regulated within the body. Explore key concepts about the chemical substances that can trigger responses in inflammatory conditions.