Human Immune Response Part I Overview

Human Immune Response Overview

  • Constitutive Immune Response: Layered approach fundamental to human immunity.

Immune System Structure

  • Types of Immunity:
    • Innate Immunity: Immediate response to pathogens.
    • Acquired Immunity: Develops over time after exposure to pathogens.
  • Physical and Chemical Barriers: Block infections from occurring.

Barriers to Infection

  • Anatomical Barriers: Prevent infection via various body sites:
    1. Respiratory (inhalation)
    2. Alimentary (ingestion)
    3. Skin (direct contact/vector)
    4. Urogenital (direct contact)
    5. Eyes (direct contact)
  • Diverse Defense Mechanisms: Each entry point has specific barriers.

Specific Barriers by System

  • Respiratory Tract:

    • Barriers: Mucus, macrophages, IgA antibodies, antimicrobial peptides.
    • Common Pathogens: Tuberculosis, SARS, influenza.

  • Alimentary Tract:

    • Barriers: Mucus, low pH in stomach, bile, IgA antibodies, lysozymes in saliva.
    • Common Pathogens: Salmonella, cholera, E. coli.

  • Skin:

    • Structure: Top layers are dead; living cells need to be reached.
    • Barriers: Sweat, sebum, dead skin cells.
    • Common Pathogens: Staphylococcus, ringworm.

  • Urogenital Tract:

    • Barriers: Low pH prevents opportunistic infections.

  • Eyes:

    • Protection: Tears contain enzymes and antibodies.

Infectious Pathogens Entry Routes

  • Modes of Transmission:
    • Inhalation or ingestion of infective material.
    • Direct contact or sexual transmission.
    • Environmental exposure (e.g. water, food).
  • Examples:
    • Measles virus, hepatitis B virus, malaria (via mosquito bites).

Questions to Consider

  1. Why have various types of immune defenses?
  2. What defines the constitutive nature of this immune layer?
  3. Implications of interactions with microbes.