Hockenbury Discovering Psychology 5th txtbk

60 CHAPTER 2 Neuroscience and BehaviorPineal glandproduces melatonin, whichhelps regulate sleep-wake cyclesHypothalamusbrain structure that controls thepituitary gland; links nervous systemand endocrine systemPituitary glandregulates activities of several otherglands; produces growth hormone,prolactin, and oxytocinThyroid glandcontrols body metabolism rateAdrenal glands(adrenal cortex and adrenal medulla)produce epinephrine (adrenaline) andnorepinephrine, which cause physicalarousal in response to danger, fear,anger, stress, and other strong emotionsTracheaLungsFigure 2.11 The Endocrine System Theendocrine system and the nervous systemare directly linked by the hypothalamus inthe brain, which controls the pituitarygland. In turn, the pituitary releases hormonesthat affect the hormone productionof several other endocrine glands. In themale and female figures shown here, youcan see the location and main functions ofseveral important endocrine glands.pituitary gland(pih-TOO-ih-tare-ee) Endocrine glandattached to the base of the brain thatsecretes hormones that affect the functionof other glands as well as hormones thatact directly on physical processes.adrenal glandsPair of endocrine glands that are involvedin the human stress response.adrenal cortexThe outer portion of the adrenal glands.Pancreasregulates blood sugar and insulinlevels; involved in hungerOvariessecrete estrogen and progesterone,which regulate female sexualdevelopment and reproductionand influence sexual behaviorTestessecrete testosterone, which regulatesmale sexual development andreproduction and influences sexualbehaviorUterusKidneysnerve impulses. Finally, some hormones and neurotransmitters are chemically identical.The same molecule can act as a hormone in the endocrine system and as a neurotransmitterin the nervous system.In contrast to the rapid speed of information transmission in the nervous system,communication in the endocrine system takes place much more slowly. Hormonesrely on the circulation of the blood to deliver their chemical messages to targetorgans, so it may take a few seconds or longer for the hormone to reach its targetorgan after it has been secreted by the originating gland.The signals that trigger the secretion of hormones are regulated by the brain, primarilyby a brain structure called the hypothalamus. (You’ll learn more about thehypothalamus later in the chapter.) The hypothalamus serves as the main link betweenthe endocrine system and the nervous system. The hypothalamus directly regulates therelease of hormones by the pituitary gland, a pea-sized gland just under the brain.The pituitary’s hormones, in turn, regulate the production of other hormones bymany of the glands in the endocrine system. This is why the pituitary gland is oftenreferred to as the body’s master gland. Under the direction of the hypothalamus, thepituitary gland controls hormone production in other endocrine glands.The pituitary gland also produces some hormones that act directly. For example,the pituitary produces growth hormone, which stimulates normal skeletal growthduring childhood. The pituitary gland can also secrete endorphins to reduce theperception of pain. In nursing mothers, the pituitary produces both prolactin, thehormone that stimulates milk production, and oxytocin, the hormone that producesthe let-down reflex, in which stored milk is “let down” into the nipple. Breast -feeding is a good example of the complex interaction among behavior, the nervoussystem, and the endocrine system (see Figure 2.12).Another set of glands, called the adrenal glands, is of particular interest to psychologists.The adrenal glands consist of the adrenal cortex, which is the outer