N116, inflammation 12, 2025 updated (1)

Inflammation Overview

• Inflammation is a response to tissue damage triggered by various factors.

• It is categorized into innate immunity (born with) and acquired immunity (developed over time).

Innate Immunity

• Physical Barriers

  • Skin and mucous membranes act as first lines of defense.

  • Other epithelial linings in digestive, respiratory, urinary, and reproductive tracts provide additional protection through secretions.

• Cellular Barriers

  • Involves white blood cells (WBCs) such as:

    • Neutrophils

    • Eosinophils

    • Macrophages

• Inflammation events cause increased blood flow and vascular permeability.

Acquired Immunity (Humoral Immune Response)

• Involves lymphocytes (B-cells and T-cells).

• B-cells:

  • Produce antibodies (immunoglobulins).

  • Respond to antigens by marking pathogens for destruction.

• T-cells:

  • Kill infected cells and help activate other immune cells.

Blood Basics

• Whole Blood Composition

• 55% Plasma and 45% Formed Elements (RBCs, WBCs, Platelets).

• Plasma Components

• Water, electrolytes, blood proteins (albumins, globulins).

• Blood proteins are synthesized in the liver and serve various transport functions.

• Blood Function

  • Supplies nutrients, gases, hormones, and regulates temperature.

Hemopoiesis

• The formation of blood cells from stem cells in bone marrow.

  • Precursor Cells or Blasts

  • Myeloid and lymphoid stem cells give rise to various blood cells (RBCs, WBCs, platelets).

White Blood Cells (Leukocytes)

• Types of WBCs

  • Neutrophils:

    • 50-70% of all WBCs, first to respond to injury.

  • Lymphocytes:

    • Important in viral infections.

  • Eosinophils:

    • Respond to allergens.

• WBCs migrate towards infection sites due to chemotaxis.

Inflammatory Response

• Stages of Inflammation

• Vascular Stage:

  • Vasodilation and increased permeability.

• Cellular Stage:

  • Migration of WBCs into tissues.

  • Phagocytosis occurs to eliminate pathogens.

  • Chemical signals attract more WBCs to the site.

Histamine in Inflammation

• A primary mediator of inflammation, released from mast cells.

• Effects include vasodilation, increased permeability, and stimulation of nerve endings causing pain.

• Major player in allergic reactions.

Allergic Reactions (Hypersensitivity)

• Typically a type I hypersensitivity (IgE mediated).

• First exposure results in IgE production; second exposure leads to rapid reaction and mast cell degranulation.

• Treatment depends on the severity, ranging from antihistamines to emergency protocols for anaphylaxis.

Glucocorticoids and Inflammation

• Mechanism of Action:

• Inhibit COX enzymes, reducing prostaglandins and inflammation.

• Common Drugs Include:

  • Hydrocortisone, prednisone, and dexamethasone with varying therapeutic effects and side effects.

• Adverse Effects:

  • Long-term use can lead to several complications, including cardiovascular risk and immunosuppression.