Chapter 14: Innate Immunity

Overview of Immunology

• Immunology is covered in three chapters:
  • Chapter 14: Innate immunity - non-specific immunity.
  • Chapter 15: Acquired (adaptive) immunity - specific immunity.
  • Chapter 16: Immune system malfunctions - allergies, tissue rejections.

Innate Immunity (Non-specific)

• Non-specific immunity: Attacks pathogens in the same way every time (bacteria, viruses, fungi).
• First line of defense: Mechanical barriers (e.g., skin, mucous membranes).
• Second line of defense: White blood cells (phagocytosis, inflammation, complement activation).

Three Lines of Defense

1. Mechanical Barriers (First Line):
   • Skin, mucous membranes, tears, stomach acid.
   • Prevents pathogens from entering the body.
2. White Blood Cells (Second Line):
   • Phagocytosis, inflammation, complement activation.
   • Responsible for destroying pathogens that breach mechanical barriers.
3. Acquired Immunity (Third Line): (Covered in Chapter 15)
   • B and T cells, specificity, memory.

Innate Immune System Components

• Surveillance: Constant patrolling for pathogens.
• Identification: Distinguishing self from non-self.
• Elimination: Destroying foreign invaders.

Key Terms and Cells

• White Blood Cells (WBCs):
  • Make up 1-2% of blood, involved in infection defense.
• Lymph: Fluid that leaks from blood vessels, part of immune surveillance.
• Self vs. Non-self: Recognition of body's own cells versus foreign invaders.

Host Defenses

• Innate System: Natural defenses present from birth, non-specific.
• Adaptive/Acquired System: Develops over time, specific, memory.

Lines of Defense

1. Mechanical Barriers: First line of defense (e.g., skin, mucous membranes).
2. Phagocytosis and Inflammation: Second line of defense; white blood cells respond to threats.

Blood Components

• Plasma: Liquid portion of blood.
• Buffy Coat: Contains white blood cells.
• Red Blood Cells: Carry oxygen.
• Platelets: Involved in blood clotting.

White Blood Cells

• Granulocytes:
  • Neutrophils: Most abundant, involved in phagocytosis.
  • Eosinophils: Target parasites.
  • Basophils: Involved in allergic reactions.
• Agranulocytes:
  • B and T Cells: Specific immunity (to be covered in Chapter 15).
  • Monocytes/Macrophages: Link innate and adaptive immunity, present antigens to T cells.

Lymphatic System

• Function: Returns fluid to circulation, part of immune surveillance.
• Lymph Nodes: Act as checkpoints for detecting pathogens.

Primary and Secondary Lymphoid Organs

• Primary: Bone marrow (formation), thymus (maturation).
• Secondary: Lymph nodes, spleen, tonsils.

White Blood Cell Functions

Inflammation

• Signs: Redness, swelling, heat, pain.
• Process: Response to injury/infection.

Phagocytosis

• Process: Engulfing and digesting pathogens.

Interferon

• Role: Response to viral infections, acts as a signal to other cells.

Complement System

• Function: Series of proteins that enhance immune response and pathogen destruction.

Summary

• Immunology: Study of the immune system; surveillance, identification, and destruction of pathogens.
• First and Second Lines of Defense: Mechanical barriers and white blood cells.
• Next Chapter (15): Specific immunity and memory formation.