Several activities of the human body like growth, reproduction and development are controlled by secretions from certain glands called endocrine glands or ductless glands. The secretions of the endocrine glands are called hormones. Each hormone has a specific function to perform and is required in very small quantities.
The endocrine glands do not possess ducts; hence they discharge their secretions directly into blood. Blood carries the hormones to the target organs. The endocrine system is s slower method of coordination than nervous system because it travels at the speed of circulating blood. Some of the endocrine glands found in human body are pituitary, thyroid, pancreas, adrenal, testis and ovary.
Pancreas produce a hormone called insulin that controls the level of sugar in the blood. Pituitary gland produces hormones that control the activities of other glands. Pituitary gland is therefore called the master gland.