The Glandular System
Lesson 12, Page 3 of 9

The secretion of hormones is regulated primarily by negative feedback.

Starting from the top down, we will now look briefly at each of the different endocrine glands:

Pineal Gland

brain The pineal gland is a pea-sized organ located in the center of the brain. It is sensitive to light, as perceived through a nerve connection from the eyes. (In some animals the pineal gland perceives light directly through the skull and thus has been referred to a "third eye.")

Darkness signals the pineal gland to release melatonin, which tells our bodies that it is time to sleep. This important hormone has also been found to play a role in sexual function and energy levels and is a powerful antioxidant. In animals it controls the seasonal changes of the body, preparing animals for such activities as mating and hybernation.


Also located deep inside the brain is the hypothalamus, which secretes hormones that regulate the other glands of the body. It is responsible, along with the pituitary gland, for coordinating all the other endocrine glands of the body. It also controls the autonomic (automatic or subconscious) nervous system including such automatic functions as blood pressure, heart rate, etc.

Pituitary Gland

The pituitary gland hangs down on a stalk from the hypothalamus and is closely associated with it. It has been called the "master gland" due to its role in controlling and regulating the other glands of the body. For example, it secretes hormones that stimulate the thyroid, adrenal and reproductive glands and also controls breast milk production. Growth hormone is also manufactured in the pituitary gland. Good nutrition for the pituitary gland includes trace minerals, such as those found in alfalfa, dandelion, bee pollen, kelp and spirulina. The minerals magnesium and potassium are particularly important to the functioning of this important gland.

Which endocrine gland is known as the "master gland"?

the hypothalamus
the pineal
the pituitary
the thymus