Some theories of emotion state that the surge in certain hormones actually triggers the emotional reaction ( Izard, 1988 Zajonc, 1980, 1984). The hormones affect behavior and emotions by stimulating muscles, organs, or other glands of the body. The endocrine glands secrete hormones directly into the bloodstream, which carries them to organs in the body, such as the heart, pancreas, and sex organs. As compared to synaptic communication, endocrine communication is generally slower due to the time it takes hormones to travel to target organs the behaviors and responses they affect may not occur until hours, weeks, or years later.
The molecules of these hormones then fit into receptor sites on those organs to fulfill their function, affecting behavior as they do so. As mentioned earlier in the chapter when talking about the sympathetic division of the autonomic nervous system, these hormones flow into the bloodstream, which carries them to their target organs. (See Figure 2.9.) The chemicals secreted by this type of gland are called hormones. Other glands, called endocrine glands, have no ducts and secrete their chemicals directly into the bloodstream. This kind of gland affects the functioning of the body but doesn’t really affect behavior. Some glands, such as salivary glands and sweat glands, secrete their chemicals directly onto the body’s tissues through tiny tubes, or ducts. Your computer does not support HTML5 audio