Lecture+37_Endocrine2-6

18 7 p 671 table 18 4 p669 anterior pituitary the

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Unformatted text preview: s and IHs from hypothalamus to anterior pituitary Hypothalamus 1 Capillaries in hypothalamus Systemic arterial blood in Endocrine cells of anterior pituitary (secrete anterior pituitary hormones into systemic blood) KEY 1 2 Hypothalamichypophyseal portal system 3 Posterior pituitary 4 Capillaries in anterior pituitary Systemic venous blood out Releasing and inhibiting hormones 5 6 = Hypophysiotropic hormones Anterior pituitary = Anterior pituitary hormone Fig. 18-7, p. 671 Table 18-4 p669 Anterior Pituitary •  The anterior pituitary secretes six pep=de hormones from its epithelial- derived cells •  Five are tropic: 1.  Thyroid- s4mula4ng hormone (TSH) s=mulates the thyroid to secrete thyroid hormone (TH). 2.  Adrenocor4cotropic hormone (ACTH) s=mulates the adrenal cortex to secrete cor=sol (mainly). 3.  and 4. Follicle- s4mula4ng hormone (FSH) and Luteinizing hormone (LH) s=mulate gonads to produce gametes and secrete sex steroids. 5.  Growth hormone (GH) s=mulates liver to secrete IGF- I, which is responsible for most effects on growth. Also has some direct metabolic effects. Anterior Pituitary •  One anterior pituitary hormone is not tropic –  Prolac4n (PRL) s=mulates milk secre=on. –  If PRL s=mulates growth and secre=on in mammary =ssue, why is this not classified as tropic? TRH CRH Hypothalamus GHRH GnRH PRH? Anterior pituitary Posterior pituitary TSH ACTH Thyroid gland Prolactin Adrenal cortex Thyroid hormone (T3 and T4) Mammary glands Breast growth and milk secretion Cortisol Increased metabolic rate Metabolic actions; stress response Growth hormone Hypothalamic- Pituitary- Thyroid (HPT) Axis Hypothalamic- Pituitary- Adrenal (HPA) Axis Hypothalamic- Pituitary- Gonad (HPG) axis Adipose tissue, muscle, liver Liver IGF-I Bone (ovaries in females) Soft tissues Growth LH Metabolic actions FSH Gonads Sex hormone secretion (estrogen & Progesterone or, Testosterone) (testes in males) Gamete production (ova in females, sperm in males) Fig. 18-5, p. 667 ANIMATION: Anterior Pituitary Function Nega=ve Feedback •  Both hypothalamus and anterior pituitary are inhibited by nega4ve- feedback. –  The target- gland’s...
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