Write a short note on the human endocrine system.

Human endocrine system secrets chemical substances called hormones. Hormones are responsible for the changes that occur in human body during the adolescence. The hormones secreted by the endocrine glands are released into the blood stream to reach a particular body part called target site. The target site responds to the hormones and stores the hormones released by endocrine glands. There are many endocrine glands in human body which secretes different hormones. All these hormones are responsible for bringing specified changes in the human body.