Final answer:
The pituitary gland is referred to as the master gland because it regulates the endocrine system, releasing hormones that control other glands as well as key physiological processes.
Step-by-step explanation:
The pituitary gland is often referred to as the master gland because it plays a crucial role in regulating the endocrine system. It is located at the base of the brain and is attached to the hypothalamus by a thin stalk. The anterior portion of the pituitary gland releases hormones that regulate other endocrine glands, and the posterior part stores and releases hormones produced by the hypothalamus. The pituitary gland releases a variety of hormones including growth hormone, endorphins, and others that control fluid levels in the body. Due to its significant role in controlling other glands, the pituitary gland is essential for various physiological processes such as growth, sexual maturation, metabolism, and pain relief.