The major parts of the endocrine system are glands and hormones. The system's function is to regulate the body.
Glands: Release hormones
Hormones: Deliver chemical messages from glands
If we did not experience fight or flight then we wouldn't know whether to face a situation or run away. People could get hurt because they did not quickly leave a situation that was dangerous.
WORKS with OTHER SYSTEMS
Parts of the Endocrine System (Click to enlarge.)
The endocrine system works with other body systems.
The nervous system tells the endocrine system what to do.
The circulatory system transports hormones for the endocrine system.
Saliva glands help digest food for the digestive system.