Introduction to the Endocrine System

Describe the components of the endocrine system

An animal’s endocrine system controls body processes through the production, secretion, and regulation of hormones, which serve as chemical “messengers” functioning in cellular and organ activity and, ultimately, maintaining the body’s homeostasis. The endocrine system plays a role in growth, metabolism, and sexual development. In humans, common endocrine system diseases include thyroid disease and diabetes mellitus. In organisms that undergo metamorphosis, the process is controlled by the endocrine system. The transformation from tadpole to frog, for example, is complex and nuanced to adapt to specific environments and ecological circumstances.

Photo A shows a tadpole. Photo b shows a frog that has developed legs but still has the tail of a tadpole. Photo C shows a fully grown frog.

Figure 1. The process of amphibian metamorphosis, as seen in the tadpole-to-frog stages shown here, is driven by hormones. (credit “tadpole”: modification of work by Brian Gratwicke)

What You’ll Learn to Do

  • Identify different types of hormones
  • Describe the two types of hormone receptors
  • Describe how hormones regulate body processes
  • Discuss the different stimuli that control hormone levels in the body
  • Describe the role of different glands in the endocrine system

Learning Activities

The learning activities for this section include the following:

  • Types of Hormones
  • How Hormones Work
  • Regulation of Body Processes
  • Regulation of Hormone Production
  • Endocrine Glands
  • Video: The Endocrine System
  • Self Check: The Endocrine System