(URGENT) why is hypothalamus is known controlling unit over endocrine system?

Hypothalamus consists of a group of specialized cells located in lower central part of the brain. It is the primary link between the nervous and endocrine systems in the body. It secretes substances which controls the hormones released by the pituitary gland which in turn controls the other endocrine glands. It basically regulated the working of the endocrine system and hence is called the master gland or controlling center.