Immune System Overview

Introduction

• The body constantly fights off various bacteria like staph, strep, and E. coli.
• The immune system is different from other body systems as it involves multiple tissue groups, organ systems, and defense cells.

Immune System Components

• Innate (Non-specific) Defense System
  • First line of defense, includes things we are born with.
  • Comprises external barriers (skin and mucous membranes) and internal defenses (phagocytes, antimicrobial proteins).
• Adaptive (Specific) Defense System
  • Acts like a specialized task force for specific targets.
  • Retains memory of pathogens to respond faster upon re-exposure.

Focus on Innate System

• Uses physical and chemical barriers, killer cells, and fever to maintain health.

Physical Barriers

• Skin
  • Acts as a wall, keeping out many microorganisms.
• Mucous Membranes
  • Line cavities exposed to the outside world (respiratory, digestive, urinary, reproductive).

Chemical Barriers

• Stomach acid neutralizes bacteria from ingested food.
• Mucus in nasal passages traps viruses.
• Enzymes in saliva and eye fluid, and peptides in skin, prevent bacterial growth.

Internal Innate Defenses

• Phagocytes
  • Includes neutrophils and macrophages which engulf and destroy pathogens.
• Natural Killer Cells (NK Cells)
  • Identify and destroy infected or cancerous cells by inducing apoptosis.

Inflammatory Response

• Triggered by injury; characterized by redness, swelling, heat, and pain.
• Histamine Release
  • Causes vasodilation and increases vessel permeability.
  • Attracts phagocytes to the injury site.
• Leukocytosis
  • Release of neutrophils from bone marrow to the bloodstream.

Systemic Fever

• Pyrogens induce fever to speed up healing and inhibit pathogen growth.

Summary

• The innate immune system begins with physical barriers and progresses to cellular defenses.
• Inflammation and fever are critical responses to handle infections or injuries.
• The adaptive immune system acts if innate defenses are overwhelmed.

Acknowledgments

• Credits to the team and contributors involved in producing the educational content.