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Unformatted text preview: Cholecystokinin, Gastric inhibitory peptide).
• Some endocrine cells aggregate into secretory organs
called endocrine glands.
• In vertebrates, nine major endocrine glands make up
the endocrine system. 27 28 Figure 42.2 The Endocrine System of Humans 41 The pituitary gland • The pituitary gland of mammals is a
link between the nervous system and
many endocrine glands and plays a
crucial role in the endocrine system.
• The pituitary gland sits in a depression
at the bottom of the skull and is
attached to the hypothalamus.
• The pituitary is made of two parts:
anterior and posterior.
29 30 Figure 42.5 The Posterior Pituitary Releases Neurohormones Figure 42.7 Hormones from the Hypothalamus Control the Anterior Pituitary • The anterior pituitary is
neurohormones from the
hypothalamus • The posterior pituitary
releases two hormones:
antidiuretic hormone and
• They are made by neurons in
the hypothalamus, are called
neurohormones, and are
packaged in vesicles. 31 32 41 The hormones of the anterior pituitary • The anterior pituitary releases four tropic hormones, which
control activities of other endocrine glands. 41 Growth hormone • Growth hormone (GH):
• 191 amino acids
• acts on many tissues to promote growth. ! thyrotropin, adrenocorticotropin, luteinizing hormone,
and follicle-stimulating hormone.
! They are peptide and protein hormones; each is
produced by a different type of pituitary cell.
• The anterior pituitary also releases other polypeptide
hormones that are not tropic hormones.
! growth hormone, prolactin, melanocyte-stimulating
hormone, endorphins, and enkephalins.
Figure 42.6 Effects of Excess Growth Hormone 41 Growth hormone signaling 35 • Gigantism is the result of overproduction of GH in children. 36 Figure 42.2 The Endocrine System of Humans • GH deficiency in children causes
pituitary dwarfism • When treated with GH, a deficient
child will begin to grow faster within
months. • From the late 1950s, pituitary
dwarfism was treated with GH
extracted from pituitaries from human
cadavers: years’ supply required 50
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