Do you know what your pituitary gland, thyroid, thymus, adrenal glands and pancreas have in common? They are all endocrine glands, and their jobs are to make hormones. Hormones are chemicals that deliver messages throughout your entire body via the bloodstream. These messages are delivered to your tissues and organs, but they are very specific: only those cells which are sensitive to that particular hormone will accept it and be activated by it.
Because they are very potent, it only takes a very small amount to initiate a significant response in the body. Hormones cannot be stored; they have to be produced and released at the precise moment they are needed. Therefore, in order to maintain balance within the systems in your body, this maintenance must continually be fine-tuned. An ongoing, intricate system of checks and balances is happening every minute of every day.