Immune response

Science

Definition

The body's defense reaction to foreign invaders such as pathogens, toxins, or abnormal cells. The innate immune response provides immediate, non-specific defense, while the adaptive immune response creates targeted antibodies and memory cells for long-lasting protection.

How It Works

  1. Physical barriers (skin, mucous membranes) block pathogen entry
  2. Innate immune cells (macrophages, neutrophils) detect and engulf invaders
  3. Antigen-presenting cells display pathogen fragments to T cells
  4. Helper T cells activate B cells and cytotoxic T cells
  5. B cells produce antibodies specific to the pathogen
  6. Memory cells remain for rapid response to future encounters

Examples

  • Fever raising body temperature to inhibit pathogen growth
  • Vaccination training the immune system to recognize a virus without causing illness
  • Antibodies binding to flu virus surface proteins to neutralize them

Related Terms

Immune system Infectious diseases Bacteria and viruses Signal transduction

Study This Concept

Practice immune response with free review games in these units:

Biology Unit 10: Microbiology and Disease