Path Day 3 Powerpoint Notes

Body Protection

• Quote: "THE BEST DEFENSE IS ATTACK." - Italian Proverb

The Immune System Overview

• Understanding the Immune System: Explains the various components and functions of the immune system in protecting the body.

Lines of Defense

• Three main defenses:

  • Anatomic barriers: Physical barriers to pathogens.

  • Inflammatory response: Reaction to injury or infection that isolates pathogens.

  • Immune response: Adaptive mechanisms to eliminate pathogens.

Anatomic Barriers

• Skin: First line of defense.

• Epithelial cells: Line respiratory tract to trap microbes.

  • Stomach acid: Destroys pathogens ingested with food.

  • Cilia: Hair-like structures in the bronchus help remove microbes from the lungs.

Blood and Lymph

• Blood: Transports immune cells and nutrients.

• Lymph: Fluid derived from blood that circulates through the lymphatic system.

  • Source of fluid: Interstitial fluid that re-enters the circulatory system.

  • Major lymphoid tissues: Include lymph nodes, spleen, and thymus.

Immune Cells (Leukocytes)

• Types of leukocytes:

  • Neutrophil: Most abundant phagocyte.

  • Monocyte: Develops into macrophages.

  • Macrophages: Key phagocytes in tissues.

  • Basophils and Mast Cells: Involved in allergic reactions.

  • Lymphocytes: Include B-Cells (produce antibodies) and T-Cells (cell-mediated immunity).

  • Natural Killer Cells: Attack cancerous and virus-infected cells.

Phagocytosis

• Definition: Process through which certain cells (like macrophages) engulf and digest pathogens.

  • Etymology: Derived from "phagein" (to devour) + "cyt" (cell) + "tosis" (process).

Immune System Components

• Innate Defenses: General, non-specific defenses present since birth.

• Adaptive Defenses: Specific immune responses developed following exposure to pathogens.

• Humoral vs. Cell-Mediated Immunity:

  • Humoral Immunity: Involves B-Cells producing antibodies.

  • Cell-Mediated Immunity: Involves T-Cells attacking infected cells directly.

Antibodies

• Types of antibodies (Immunoglobulins):

  • IgG: Greatest abundance, provides majority of antibody-based immunity.

  • IgA: Found in mucosal areas, protection against pathogens.

  • IgM: First antibody produced in response to an infection.

  • IgE: Involved in allergic reactions.

  • IgD: Functions mainly as a receptor on B-cells.

Sepsis and Hypersensitivity

• Sepsis: Systemic response to infection, characterized by SIRS (Systemic Inflammatory Response Syndrome) + infection.

• Hypersensitivity Reactions: Abnormal immune response to substances that may cause tissue damage.

  • Types:

    • Type I: Anaphylaxis (IgE mediated).

    • Type II: Cytotoxic (IgG mediated) reactions, such as transfusion reactions.

    • Type III: Immune complex-mediated reactions, e.g., Lupus.

    • Type IV: Delayed-type hypersensitivity, e.g., poison ivy reactions.

Autoimmune Disorders

• Examples include:

  • Lupus: Systemic disease that affects multiple organs.

  • Grave's disease: Hyperthyroidism resulting from autoimmune activity.

  • Type 1 Diabetes: Autoimmune destruction of insulin-producing cells in the pancreas.

  • Rheumatoid Arthritis: Chronic inflammatory disorder affecting joints.

Immunosuppressants and Immunodeficiencies

• Immunosuppressants: Medications that reduce the strength of the immune system.

• Immunodeficiencies: Conditions that impair the immune response, e.g., HIV/AIDS.

Chronic Conditions Affecting Immune Function

• Impact of Aging: Questions on how immune response changes with age, including development and efficiency.

• Nutrition and Stress: Key factors that influence immune health.

Blood Types and Transfusions

• ABO Phenotypes: Importance of understanding blood compatibility for transfusions.

  • Type O: Universal donor.

  • Type AB: Universal recipient.

• Rh Factor: The presence (Rh+) or absence (Rh-) of D antigen on red blood cells; significant in transfusions and pregnancy complications due to Rh incompatibility.

Rh Immunity and Pregnancy

• Explanation: Rh-negative mothers with Rh-positive fetuses may develop antibodies that affect future pregnancies.

Summary of Hypersensitivity Types

• Type I: Anaphylaxis from allergens.

• Type II: Blood transfusion reactions.

• Type III: Autoimmune disorders like lupus.

• Type IV: Contact dermatitis from poison ivy.