Introduction to the Endocrine System

Learning Objectives

After studying this chapter, you will be able to:

  • Identify the contributions of the endocrine system to homeostasis
  • Discuss the chemical composition of hormones and the mechanisms of hormone action
  • Summarize the site of production, regulation, and effects of the hormones of the pituitary, thyroid, parathyroid, adrenal, and pineal glands
  • Discuss the hormonal regulation of the reproductive system
  • Explain the role of the pancreatic endocrine cells in the regulation of blood glucose
  • Identify the hormones released by the heart, kidneys, and other organs with secondary endocrine functions
  • Discuss several common diseases associated with endocrine system dysfunction
  • Discuss the embryonic development of, and the effects of aging on, the endocrine system
This photo shows a young girl reaching for an orange leaf on an oak tree. She is on a walkway near a creek. The opposite shore is a deep slope covered with more trees in autumn colors.

A Child Catches a Falling Leaf.

You may never have thought of it this way, but when you send a text message to two friends to meet you at the dining hall at six, you’re sending digital signals that (you hope) will affect their behavior—even though they are some distance away. Similarly, certain cells send chemical signals to other cells in the body that influence their behavior. This long-distance intercellular communication, coordination, and control is critical for homeostasis, and it is the fundamental function of the endocrine system.

Hormones of the endocrine system coordinate and control growth, metabolism, temperature regulation, the stress response, reproduction, and many other functions.