Pituitary Gland its Control by the Hypothalamus 2

Objectives After studying this chapter, you should be able to: ■ Describe the connections between the hypothalamus and the pituitary gland the functional significance of each connection. ■ Name the hypophysiotropic hormones, and outline the effects that each has on anterior pituitary function. ■ Describe the synthesis, processing, storage, and secretion of the hormones of the posterior pituitary. ■ Discuss the effects of ADH, the receptors on which it acts, and how its secretion is regulated. ■ Discuss the effects of oxytocin, the receptors on which it acts, and how its secretion is regulated.

Pituitary Gland or hypophysis from Greek hupophusis: HYPO- + phuein (to grow) Sella turcica )ﻣﺤﻔﻈﻪ ﺯیﻦ ( ﺗﺮکی ﻧیﻢ ﺗﺎ یک گﺮﻡ : ﻭﺯﻥ 4

Pituitary Gland l ‘the master gland’ l produces some other hormones glands other endocrine 6

Pituitary hormones 7

Different Cell Types of Anterior Pituitary 1. Somatotropes----> human growth hormone (h. GH) 2. Corticotropes-----> adrenocorticotropin (ACTH) 30 -40% 20% 3. Thyrotropes---> thyroid-stimulating hormone (TSH) 4. Lactotropes-----> prolactin (PRL) 5. Gonadotropes---->gonadotropic hormones luteinizing hormone (LH) l follicle-stimulatinq hormone (FSH) l 8

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Hypothalamic Releasing & Inhibitory Hormones ( )ﻫﻮﺭﻣﻮﻥ ﻫﺎی آﺰﺍﺩ کﻨﻨﺪﻩ ﻭ ﻣﻬﺎﺭ کﻨﻨﺪﻩ کﻨﺘﺮﻝ ﺗﺮﺷﺢ ﻫﻮﺭﻣﻮﻥ ﻫﺎی ﻫیپﻮﻓیﺰ ﻗﺪﺍﻣی l Thyrotropin-releasing hormone (TRH)---- thyroid-stimulating hormone l Corticotropin-releasing hormone (CRH) ---- adrenocorticotropin l Growth hormone-releasing hormone (GHRH), ----- growth hormone, l v Growth hormone inhibitory hormone (GHIH) (somatostatin)---×- growth hormone Gonadotropin-releasing hormone (Gn. RH)----- 2 gonadotropic hormones LH FSH Prolactin inhibitory hormone (PIH) ----×-- prolactin 15

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Chemical Structures of ADH & OX l Polypeptides (9 aa) Vasopressin: Cys-Tyr- Phe-Gln-Asn-Cys-Pro-Arg-Gly. NH 2 Oxytocin: Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly. NH 2 20

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ADH(Vasopressin) ADH ﺩﺭ ﻏﻠﻈﺖ ﻫﺎی ﺑﺎﻻی Vasopressin (V 1 ) 26

ADH ﻋﻮﺍﻣﻞ ﻣﺤﺮک ﺗﺮﺷﺢ Hyperosmolarity (1 -2%) Decreased blood volume (15 -25%) Hypophysis Decreased arterial pressure (15%) Sympathetic stimulation ADH Vasoconstriction ﺍﻓﺰﺍیﺶ ﻓﺸﺎﺭ ﺷﺮیﺎﻧی ﺑﺎﺯﺟﺬﺏ آﺐ ﺗﻮﺳﻂ کﻠیﻪ ﻫﺎ ﺍﻓﺰﺍیﺶ ﺣﺠﻢ ﺧﻮﻥ 28

Oxytocin Hormone 33

Oxytocin Hormone l Contraction l Milk of the Pregnant Uterus Ejection by the Breasts 34

Dilation of cervix and 38

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