Animal Behavior: Instinct

The hypothalamus, the anterior pituitary gland, and the posterior pituitary gland are all involved in the regulation of the vertebrate endocrine system.

The endocrine system produces and transports chemical signals within the body. The exocrine system produces and transports signals outside of the body.

Steroids are large ring molecules that bind in the cell nucleus. Peptide hormones bind to the cell surface, as do catecholamines.

The anterior pituitary produces many types of hormones, while the posterior pituitary acts mostly to store these hormones.

The pituitary gland (the combined anterior and posterior pituitaries) is an endocrine gland because it secretes signal chemicals intended for other organs inside the body.