Written by the Fiveable Content Team • Last updated September 2025
Verified for the 2026 exam
Verified for the 2026 exam•Written by the Fiveable Content Team • Last updated September 2025
Definition
The immune system is the body's defense mechanism against harmful substances and foreign invaders. It includes cells, tissues, and organs that work together to protect the body from infections and diseases.
Related terms
Antigens: These are substances that trigger an immune response in the body. They can be viruses, bacteria, or other harmful invaders.
Antibodies: These are proteins produced by the immune system to recognize and neutralize specific antigens.
Immunotherapy: This is a type of treatment that uses the body's own immune system to fight diseases such as cancer.