14-Jun-16Pituitary Gland1 The Pituitary Hormones

14-Jun-16Pituitary Gland2 Functional Anatomy  Pituitary gland made up of –Anterior lobe Originated from Rathke’s pouch (pharyngeal epithelium) –Posterior lobe Originated from outgrowth of 3 rd ventricle 3 rd ventricle Rathke’s pouch Anterior lobe Posterior lobe Intermediate lobe

14-Jun-16Pituitary Gland3 Functional Anatomy  Also include the intermediate lobe 3 rd ventricle Rathke’s pouch Anterior lobe Posterior lobe Intermediate lobe

14-Jun-16Pituitary Gland4 Relationship of Pituitary to Hypothalamus  Embryo-logically –Posterior lobe arise as evagination of the floor of 3 rd ventricle –It is made up of axons that arise from cell bodies Supraoptic Paraventricular –Hypothalamo – hypophysial tract Supra optic nucleus Hypothalamic neurosecretions Hypo- physiotropic hormones secreted Superior hypophysial artery vein Posterior pituitary hormones Anterior pituitary hormones

14-Jun-16Pituitary Gland5 Relationship of Pituitary to Hypothalamus  Embryo-logically –Anterior & intermediate lobes –Arise from Rathke’s pouch Evagination from the roof of pharynx Supra optic nucleus Hypothalamic neurosecretions Hypo- physiotropic hormones secreted Superior hypophysial artery vein Posterior pituitary hormones Anterior pituitary hormones

14-Jun-16Pituitary Gland6 Relationship of Pituitary to Hypothalamus  There are neural connections –Hypothalamus –Posterior lobe  Nerves originate from –Supra-optic nucleus –Paraventricular nucleus Supra optic nucleus Hypothalamic neurosecretions Hypo- physiotropic hormones secreted Superior hypophysial artery vein Posterior pituitary hormones Anterior pituitary hormones

14-Jun-16Pituitary Gland7 Relationship of Pituitary to Hypothalamus  There is also vascular connections between –Hypothalamus –Anterior pituitary Supra optic nucleus Hypothalamic neurosecretions Hypo- physiotropic hormones secreted Superior hypophysial artery vein Posterior pituitary hormones Anterior pituitary hormones

14-Jun-16Pituitary Gland8 Portal – Hypophysial Vessels  Form direct vascular link between –Hypothalamus –Anterior pituitary  Arise from branch of –Carotid artery –Circle of willis Supra optic nucleus Hypothalamic neurosecretions Primary plexus capillaries in median eminence Superior hypophysial artery vein Posterior pituitary hormones Capillaries of anterior pituitary Portal hypophysial vessels

14-Jun-16Pituitary Gland9 Portal – Hypophysial Vessels  Primary plexus –Fenestrated capillaries –Penetrate median eminence  Portal vessels arise from median eminence –End into capillaries of anterior pituitary Supra optic nucleus Hypothalamic neurosecretions Primary plexus capillaries in median eminence Superior hypophysial artery Vein Posterior pituitary hormones Capillaries of anterior pituitary Portal hypophysial vessels

14-Jun-16Pituitary Gland10 Portal – Hypophysial Vessels  Hormones secreted by hypothalamus –Released in median eminence –Carried by blood through The portal hypophysial vessels to Anterior pituitary Supra optic nucleus Hypothalamic neurosecretions Primary plexus capillaries in median eminence Superior hypophysial artery Vein Posterior pituitary hormones Capillaries of anterior pituitary Portal hypophysial vessels

14-Jun-16Pituitary Gland11 Cells of the Anterior Pituitary  Usually there is one type of cell for –Each major hormone produced by the anterior pituitary  The following are types of cells found in the ant. Pit gland –Somatotropes(30% of all cells of Ant. Pit ) Secrete GH

14-Jun-16Pituitary Gland12 Cells of Anterior Pituitary  Corticotropes (20% of all cell types) –Secrete adrenocorticotropic hormones(ACTH)  Thyrotropes –Secreter thyroid stimulating hormone (TSH)

14-Jun-16Pituitary Gland13 Cells of Anterior pituitary  Gonadotropes –Secrete gonadotropic hormones Luteinizing hormone (LH) Folicle stimulating hormone (FSH)  Lactotropes –Secrete prolactin (PRL)

14-Jun-16Pituitary Gland14 Anterior Pituitary Hormones  Thyroid stimulating hormone (TSH) [thyrotropin] –Stimulates thyroid gland Growth Secrete thyroid hormones (thyroxin) –Control rates of most chemical reactions of the body

14-Jun-16Pituitary Gland15 Anterior Pituitary Hormones  Adrenocorticotrophic hormone (ACTH) [corticotropin] –Stimulates growth of adrenal cortex Zona fasciculata Zona reticularis –Stimulate secretion of Adrenocortical hormones Affect metabolism of –Glucose, protein & fat

14-Jun-16Pituitary Gland16 Anterior Pituitary Hormones  Growth hormone (GH) –Somatotropin (STH)  Accelerates body growth –Protein formation, cell multiplication, cell differentiation  Stimulates secretion of (IGF-1) insulin like growth factors –Liver and other tissues

14-Jun-16Pituitary Gland17 Anterior Pituitary Hormones  Follicle stimulating hormones (FSH) stimulates –Ovarian follicles growth in females –Spermatogenesis in males  Luteinizing hormone (LH) stimulates –Ovulation and luteinizing of ovarian follicles in females –Testosterone secretion in males

14-Jun-16Pituitary Gland18 Anterior Pituitary Hormones  Prolactin (PRL) –Stimulate secretion of milk by mammary glands –Promote maternal behaviour   - lipotropin (  -LPH)

14-Jun-16Pituitary Gland19 Intermediate Lobe Secretions  Intermediate lobe secrete –Melanotropin or intermedin Stimulate melanin synthesis in humans Expand melanophore –Fish, amphibians, reptiles

14-Jun-16Pituitary Gland20 Intermediate Secretions  Melanotropin or intermedin include –  -melanocyte stimulating hormone (  - MSH) –  - melanocyte stimulating hormone (  - MSH) –  - melanocyte stimulating hormone (  - MSH)   - lipotropin (  - LPH) –Corticotropin like peptide from intermediate lobe

14-Jun-16Pituitary Gland21 Posterior Lobe Hormones  Anti-diuretic hormone (ADH) Vasopressin –Promote water retention by kidneys –Vasopressor  Oxytocin –Milk ejection –Contraction of pregnant uterus

14-Jun-16Pituitary Gland22 Control of Anterior Pituitary Secretions  Hypothalamus –Secrete releasing or inhibiting hormones In the median eminence  These are transported via the hypothalamic hypophysial portal system –Anterior pituitary Hypothalamus Hypophysiotropic hormones Hypothalamic hypophysial portal system Anterior pituitary Secretions of Anterior pituitary

14-Jun-16Pituitary Gland23 Control of Anterior Pituitary Secretions  Control the secretion of anterior pituitary secretion Hypothalamus Hypophysiotropic hormones Hypothalamic hypophysial portal system Anterior pituitary Secretions of Anterior pituitary

14-Jun-16Pituitary Gland24 Control of Anterior Pituitary Secretions  The releasing & inhibitory hormones include –Corticotrophin releasing hormone (CRH) Stimulate release of adrenocorticotropin hormone (ACTH) Hypothalamus Hypophysiotropic hormones Hypothalamic hypophysial portal system Anterior pituitary Secretions of Anterior pituitary

14-Jun-16Pituitary Gland25 Control of Anterior Pituitary Secretions  Thyrotropin releasing hormone (TRH) –Cause release of TSH  Growth hormone releasing hormone (GRH) –Cause release of GH  Growth hormone inhibiting hormone (GIH) –Inhibit release of GH Hypothalamus Hypophysiotropic hormones Hypothalamic hypophysial portal system Anterior pituitary Secretions of Anterior pituitary

14-Jun-16Pituitary Gland26 Control of Anterior Pituitary Secretions  Leutenizing hormone releasing hormone (LHRH) –Cause release of LH  Gonadotropin releasing hormone (GnRH) –Cause release of LH, FSH Hypothalamus Hypophysiotropic hormones Hypothalamic hypophysial portal system Anterior pituitary Secretions of Anterior pituitary

14-Jun-16Pituitary Gland27 Control of Anterior Pituitary Secretions  Prolactin inhibiting factor (PIF) –Cause inhibition of prolactin secretion Hypothalamus Hypophysiotropic hormones Hypothalamic hypophysial portal system Anterior pituitary Secretions of Anterior pituitary