{"id":4826,"date":"2019-06-24T14:59:38","date_gmt":"2019-06-24T14:59:38","guid":{"rendered":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/11-4-pituitary-gland-3\/"},"modified":"2023-11-30T18:52:36","modified_gmt":"2023-11-30T18:52:36","slug":"11-4-pituitary-gland-3","status":"publish","type":"chapter","link":"https:\/\/pressbooks.ccconline.org\/acchumanbio\/chapter\/11-4-pituitary-gland-3\/","title":{"raw":"9.4\u00a0Pituitary Gland","rendered":"9.4\u00a0Pituitary Gland"},"content":{"raw":" \r\n
\r\n\r\n[caption id=\"attachment_3444\" align=\"aligncenter\" width=\"333\"]\"Figure Figure 9.4.1 Mother's milk is best for infants.<\/em>[\/caption]\r\n

Milk on Demand<\/h1>\r\n<\/div>\r\nThis adorable nursing infant (Figure 9.4.1) is part of a [pb_glossary id=\"2962\"]positive feedback loop[\/pb_glossary]. When he suckles on the [pb_glossary id=\"3433\"]nipple[\/pb_glossary], it sends nerve impulses to his mother\u2019s [pb_glossary id=\"2937\"]hypothalamus[\/pb_glossary]. Those nerve impulses \u201ctell\u201d her [pb_glossary id=\"2938\"]pituitary gland[\/pb_glossary] to release the hormone [pb_glossary id=\"3431\"]prolactin[\/pb_glossary] into her bloodstream. Prolactin travels to the [pb_glossary id=\"3432\"]mammary glands[\/pb_glossary] in the breasts and stimulates milk production, which motivates the infant to keep suckling.\r\n
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What Is the Pituitary Gland?<\/h1>\r\n<\/div>\r\nThe\u00a0[pb_glossary id=\"2938\"]pituitary gland[\/pb_glossary]<\/strong>\u00a0is the master gland of the\u00a0[pb_glossary id=\"5985\"]endocrine system[\/pb_glossary], which is the system of glands that secrete [pb_glossary id=\"5661\"]hormones[\/pb_glossary] into the bloodstream.\u00a0Endocrine hormones\u00a0control virtually all physiological processes. They control growth, sexual maturation,\u00a0reproduction, body\u00a0temperature,\u00a0blood pressure, and metabolism. The pituitary gland is considered the master gland of the endocrine system, because it controls the rest of the endocrine system. Many pituitary hormones either promote or inhibit\u00a0hormone\u00a0secretion by other\u00a0endocrine glands.\r\n
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Structure and Function of the Pituitary Gland<\/h1>\r\n<\/div>\r\nThe pituitary gland is about the size of a pea. It protrudes from the bottom of the hypothalamus at the base of the inner brain (see Figure 9.4.2). The pituitary is connected to the hypothalamus by a thin stalk (called the infundibulum). Blood vessels and nerves in the stalk allow direct connections between the hypothalamus and pituitary gland.\r\n\r\n[caption id=\"attachment_3445\" align=\"aligncenter\" width=\"759\"]\"Hypothalamus Figure 9.4.2 The pituitary gland in the endocrine system is closely connected to the hypothalamus in the brain. Both anterior and posterior lobes of the pituitary gland are directly connected to the hypothalamus by capillaries (anterior lobe) and nerve axons (posterior lobe).<\/em>[\/caption]\r\n

Anterior Lobe<\/h2>\r\nThe\u00a0[pb_glossary id=\"5887\"]anterior pituitary[\/pb_glossary]<\/strong> is the lobe is at the front of the pituitary gland. It synthesizes and releases hormones into the blood. Table 9.4.1 shows some of the endocrine hormones released by the anterior pituitary, including their targets and effects.\r\n\r\nTable 9.4.1<\/strong>\r\n\r\nEndocrine Hormones Released by the Anterior Pituitary, and Their Targets and Effects.<\/em>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Anterior Pituitary Hormone<\/strong><\/td>\r\nTarget<\/strong><\/td>\r\nEffect<\/strong><\/td>\r\n<\/tr>\r\n
Adrenocorticotropic hormone (ACTH)<\/td>\r\nAdrenal glands<\/td>\r\nStimulates the cortex of each adrenal gland to secrete its hormones.<\/td>\r\n<\/tr>\r\n
Thyroid-stimulating hormone (TSH)<\/td>\r\nThyroid gland<\/td>\r\nStimulates the thyroid gland to secrete thyroid hormone.<\/td>\r\n<\/tr>\r\n
Growth hormone (GH)<\/td>\r\nBody cells<\/td>\r\nStimulates body cells to synthesize proteins and grow.<\/td>\r\n<\/tr>\r\n
Follicle-stimulating hormone (FSH)<\/td>\r\nOvaries, testes<\/td>\r\nStimulates the ovaries to develop mature eggs.\u00a0 stimulates the testes to produce sperm.<\/td>\r\n<\/tr>\r\n
Luteinizing hormone (LH)<\/td>\r\nOvaries, testes<\/td>\r\nStimulates the ovaries and testes to secrete sex hormones; stimulates the ovaries to release eggs.<\/td>\r\n<\/tr>\r\n
Prolactin (PRL)<\/td>\r\nMammary glands<\/td>\r\nStimulates the mammary glands to produce milk.<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\nThe [pb_glossary id=\"5889\"]anterior pituitary gland[\/pb_glossary] is regulated mainly by [pb_glossary id=\"5661\"]hormones[\/pb_glossary] from the [pb_glossary id=\"2937\"]hypothalamus[\/pb_glossary]. The hypothalamus secretes hormones (called releasing hormones and inhibiting hormones) that travel through capillaries directly to the anterior lobe of the pituitary gland. The hormones stimulate the anterior pituitary to either release or stop releasing particular pituitary hormones. Several of these hypothalamic hormones and their effects on the anterior pituitary are shown in the table below.\r\n\r\nTable 9.4.2 <\/strong>\r\n\r\nHypothalamic Hormones and Their Effects on the Anterior Pituitary<\/em>\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n\r\n
Hypothalamic Hormone<\/strong><\/td>\r\nEffect on Anterior Pituitary<\/strong><\/td>\r\n<\/tr>\r\n
Thyrotropin releasing hormone (TRH)<\/td>\r\nRelease of thyroid stimulating hormone (TSH)<\/td>\r\n<\/tr>\r\n
Corticotropin releasing hormone (CRH)<\/td>\r\nRelease of adrenocorticotropic hormone (ACTH)<\/td>\r\n<\/tr>\r\n
Gonadotropin releasing hormone (GnRH)<\/td>\r\nRelease of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)<\/td>\r\n<\/tr>\r\n
Growth hormone releasing hormone (GHRH)<\/td>\r\nRelease of growth hormone (GH)<\/td>\r\n<\/tr>\r\n
Growth hormone inhibiting hormone (GHIH) (Somatostatin)<\/td>\r\nStopping of growth hormone release<\/td>\r\n<\/tr>\r\n
Prolactin releasing hormone (PRH)<\/td>\r\nRelease of prolactin<\/td>\r\n<\/tr>\r\n
Prolactin inhibiting hormone (PIH) (Dopamine)<\/td>\r\nStopping of prolactin release<\/td>\r\n<\/tr>\r\n<\/tbody>\r\n<\/table>\r\n

Posterior Lobe<\/h2>\r\nThe\u00a0[pb_glossary id=\"3447\"]posterior pituitary[\/pb_glossary]<\/strong> is the lobe is at the back of the pituitary gland. This lobe does not synthesize any hormones. Instead, the posterior lobe stores hormones that come from the hypothalamus along the axons of nerves connecting the two structures (also shown in Figure 9.4.2). The posterior pituitary then secretes the hormones into the bloodstream as needed. Hypothalamic hormones secreted by the posterior pituitary include vasopressin and oxytocin.\r\n