Attacks foreign invaders that try and harm you, which you'll know your body is fighting back by symptoms such as runny nose, swelling, etc. There are many ways the immune system responds to an an attack.

- User

Immune System

(Normal Conditions)

Works with the circulatory system and is spread out basically where the circulatory system goes.

Respiratory: Oxygen lets the immune system work as normal and maintain homeostasis.

Endocrine: Adrenaline glands release glucocorticoids which are what tell your body when to start and stop swelling.