The endocrine system is composed of a number of _________________ glands (and some patches of cells) which produce and secrete ______________________ directly into the _________________. These hormones then travel to distant cells or glands (called "_______________" cells or glands) where they exert their effects.

Exocrine Glands

Endocrine Glands

Four Major Classes of Hormones

  1. Modified Amino Acids

  2. Proteins/Peptides

  3. Steroids

  4. Prostaglandins

Mode of Action of Hormones

  1. Steroids (Fig. 37.3, pg. 616)

  2. Proteins/Peptides (Fig. 37.4, pg. 617)