Inflammation and Immune Response

Definition

• Inflammation: A local immune response to tissue injury or infection.
• Symptoms: Heat, redness, edema (swelling), pain, and loss of function.

Initial Response

1. Vaso-constriction
   • Brief constriction of local blood vessels to reduce blood loss.
   • Formation of a clot to stop bleeding.

Chemical Signaling

• Cell Injury and Death: Trigger the release of vasoactive chemicals.
• Vasoactive Chemicals:
  • Prostaglandins
  • Histamine
  • Function: Dilate local blood vessels and increase blood flow.
• Increased Capillary Permeability:
  • Endothelial cells contract, opening spaces allowing fluids and proteins to pass into tissue.

Immune Cell Response

1. Chemotaxis

   • Multi-stage process.
   • Neutrophils (immune cells) move to the injury site.
   • Destruction of pathogens and damaged cells.

2. Chemoattractants

   • Messenger molecules released at injury site.
   • Cause neutrophils and endothelial cells to adhere.

3. Diapedesis

   • Neutrophils squeeze through endothelial gaps.
   • Migrate to the injury site following the chemotactic gradient.

4. Phagocytosis

   • Neutrophils engulf and digest bacteria.

Tissue Repair

• Initiation:
  • Locally produced growth factors stimulate fibroblasts.
• Fibroblast Activity:
  • Rapid cell division and secretion of collagen.
  • Reinforcement of the wound.

Anti-inflammatory Drugs

• Function: Inhibit inflammation by blocking production of inflammatory chemicals.
• Common Drugs: Non-steroidal anti-inflammatory drugs (NSAIDs), e.g., aspirin, ibuprofen.
• Mechanism:
  • Contain cyclooxygenase (Cox) enzyme.
  • Inhibit production of prostaglandins and other inflammatory chemicals.
  • Reduce vasodilation, edema, and pain related to inflammation.