{"id":4815,"date":"2019-06-24T14:57:00","date_gmt":"2019-06-24T14:57:00","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/11-2-introduction-to-the-endocrine-system-3\/"},"modified":"2023-11-30T18:52:10","modified_gmt":"2023-11-30T18:52:10","slug":"11-2-introduction-to-the-endocrine-system-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/11-2-introduction-to-the-endocrine-system-3\/","title":{"raw":"9.2\u00a0Introduction to the Endocrine System","rendered":"9.2\u00a0Introduction to the Endocrine System"},"content":{"raw":" \r\n
\r\n\r\n[caption id=\"attachment_3397\" align=\"aligncenter\" width=\"674\"]\"\" Figure 9.2.1 Enzymes, their cellular location, substrates and products in human steroidogenesis. <\/em>[\/caption]\r\n

Your body the chemist<\/h1>\r\n<\/div>\r\nYour endocrine system is constantly making hormones that will regulate every body system that makes up you!\u00a0 The endocrine system is an adept chemist; by making a chain of modifications to the steroid cortisol, your body can make a whole host of other hormones at a moment's notice.\r\n
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Overview of the Endocrine System<\/h1>\r\n<\/div>\r\nThe\u00a0[pb_glossary id=\"5985\"]endocrine system[\/pb_glossary]<\/strong>\u00a0is a system of glands called\u00a0endocrine glands\u00a0that release chemical messenger molecules into the bloodstream. The messenger molecules of the endocrine system are called\u00a0endocrine hormones. Other glands of the body, including sweat glands and salivary glands, also secrete substances, but not into the bloodstream. Instead, they secrete them through ducts that carry them to nearby body surfaces. These other glands are not part of the endocrine system. Instead, they are called\u00a0[pb_glossary id=\"6001\"]exocrine glands[\/pb_glossary].<\/strong>\r\n\r\nEndocrine hormones\u00a0act slowly compared with the rapid transmission of electrical messages in the\u00a0nervous system. Endocrine hormones must travel through the bloodstream to the\u00a0cells\u00a0they affect, and this takes time. On the other hand, because endocrine hormones are released into the bloodstream, they travel throughout the body wherever\u00a0blood\u00a0flows. As a result, endocrine hormones may affect many cells and have body-wide effects. The effects of endocrine hormones are also longer lasting than the effects of nervous system messages. Endocrine hormones may cause effects that last for days, weeks, or even months.\r\n
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Glands of the Endocrine System<\/h1>\r\n<\/div>\r\nThe major glands of the endocrine system are shown in Figure 9.2.2. The glands in the figure are described briefly in the rest of this section. Refer to the figure as you read about the glands in the following text.\r\n\r\n[caption id=\"attachment_3399\" align=\"alignnone\" width=\"928\"]\"The Figure 9.2.2 The endocrine system. <\/em>[\/caption]\r\n\r\n
\r\n\r\nAll of the glands labelled in Figure 9.2.2 are part of the endocrine system. Note that the ovary and testis are the only endocrine glands that differ in males and females.\r\n\r\n<\/div>\r\n

Pituitary Gland<\/h2>\r\nThe [pb_glossary id=\"2938\"]pituitary gland<\/strong>[\/pb_glossary] is located at the\u00a0base\u00a0of the [pb_glossary id=\"5915\"]brain[\/pb_glossary]. It is controlled by the\u00a0[pb_glossary id=\"2908\"]nervous system[\/pb_glossary]\u00a0via the brain structure called the [pb_glossary id=\"2937\"]hypothalamus[\/pb_glossary], to which it is connected by a thin stalk. The pituitary gland consists of two lobes, called the [pb_glossary id=\"5889\"]anterior[\/pb_glossary] (front) lobe and [pb_glossary id=\"3401\"]posterior[\/pb_glossary] (back) lobe. The posterior lobe stores and secretes [pb_glossary id=\"5661\"]hormones[\/pb_glossary] synthesized by the hypothalamus. The anterior lobe synthesizes and secretes its own endocrine hormones, also under the influence of the hypothalamus. One endocrine\u00a0hormone\u00a0secreted by the pituitary gland is growth hormone, which stimulates\u00a0cells\u00a0throughout the body to synthesize\u00a0proteins\u00a0and divide. Most of the other endocrine hormones secreted by the pituitary gland control other\u00a0endocrine glands. Generally, these hormones direct the other glands to secrete either more or less of their hormones, which is why the pituitary gland is often referred to as the \u201cmaster gland\u201d of the endocrine system.\r\n

Remaining Glands of the Endocrine System<\/h2>\r\nEach of the other glands of the endocrine system is summarized below. Several of these endocrine glands are also discussed in greater detail in other concepts in this chapter.\r\n