PITUITARY GLAND HYPOTHALAMUS By Barakat Shahin Physiology of

PITUITARY GLAND HYPOTHALAMUS By Barakat Shahin Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Anatomical Relations • • • Pituitary Sella Turcica Optic Chiasm Median Eminence Mamillary Body Cavernous Sinus (not visible) Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Subdivisions of the Pituitary (Hypophysis) • Adenohypophysis (Anterior Pituitary) – Pars Distalis – Pars Intermedia – Pars Tuberalis • Neurohypophysis (Posterior Pituitary) – Pars Nervosa – Infundibular Stalk Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Hormones • Prolactin/Growth Hormone Family – Prolactin – Growth Hormone • Glycoprotein Family – Thyroid Stimulating Hormone (TSH) – Gonadotropins: • Follicle Stimulating Hormone (FSH) • Luteinizing Hormone (LH) • Pro-opiomelanocortin Family – ACTH Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Pars Intermedia • MSH – Pro-opiomelanocortin Family – Alpha – Beta • Also in Hypothalamus – Involved in regulating metabolism and appetite Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Hypothalamo-hypophyseal Portal System • Superior hypophyseal artery • Portal Vessels • Capillary Bed of Pars Distalis Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Relation of Hypothalamus and Pituitary gland The connection between the hypothalamus and the pituitary gland results from hormones released from the hypothalamic neurons. The hypothalamus has two different connections with the pituitary gland. The connection to the adenohypophysis (the anterior lobe) is via a special portal blood system. Whereas the connection to the neurohypophysis (the posterior lobe) is directly through neurons. Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Hypothalamic Releasing Hormones • • • Thyrotropin Releasing Hormone (TRH) Corticotropin Releasing Hormone (CRH) Gonadotropin Releasing Hormone (Gn. RH) Growth Hormone Releasing Hormone (GRH) Somatostatin (GIH) Prolactin Inhibiting Hormone (PIH) Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Feedback Control of Anterior Pituitary • Long Loop • Short Loop • Ultrashort Loop • Amplitude • Frequency Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Pathologies • Hypersecretion • Hyposecretion • Classification – Primary (Pituitary’s Target Gland) – Secondary (Pituitary) – Tertiary (Hypothalamus) • Pituitary adenomas Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Growth Hormone (GH) Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Function • Stimulate Secretion of Insulin-like Growth Factor 1 (IGF-1) • Increase linear growth • Increase protein synthesis • Decrease protein catabolism • Increase lipid catabolism • Decrease carbohydrate uptake and utilization Physiology of Hypothalamus and Pitutary gland By Dr Barakat

GHRH Control of Secretion: Somatostatin (GHIH) Stimulates • GRH Inhibits the Secretion of GH – Neural regulation • • Diurnal Rhythms Deep Sleep Stress Exercise – Metabolic control • Blood Glucose • Blood Fatty Acids • Blood Amino Acids • Somatostatin Physiology of Hypothalamus and Pitutary gland By Dr Barakat Secretion of GH

Feedback • GH--Short Loop • IGFs--Long Loop • Metabolic control – Blood Glucose – Blood Fatty Acids – Blood Amino Acids • Neural regulation – – Diurnal Rhythms Deep Sleep Stress Physiology of Hypothalamus and Exercise Pitutary gland By Dr Barakat

Long-Loop Diurnal Feedback Rhythms Exercise Sleep Regulation Stress GH Short-Loop Somatostatin Feedback Hypothalamus Serum: Glucose Lipids Amino Acids GRH Ant. Pituitary IGF 1 GH Liver IGF 1 Serum: Glu. Lipids Amino Acids Other Target Tissues Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Pathologies Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Gigantism Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Acromegaly Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Glucose Intolerance • A form of Diabetes • Caused by Hyperglycemia • Leads to Type II Diabetes Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Hyposecretion Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Dwarfism Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Prolactin (PRL) • Chemistry • Function: • Control of Secretion Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Control of PRL Baby Suckles Nipple Baby Weaned Sensory Impulses to Hypothalamus Milk Production Dopamine Secretion Prolactin Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Adrenocorticotropic Hormone (ACTH) • • Chemistry Biosynthesis Function Control of Secretion Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Control of ACTH Stress Sleep Hypothalamus CRH Ant. Pituitary ACTH Adrenal Cortex Physiology of Hypothalamus and Pitutary gland By Dr Barakat Glucocorticoids

Thyroid Stimulating Hormone (TSH) • Chemistry – Glycoprotein – 2 Chains • Function – Stimulate production of thyroid hormone (T 4 & T 3) Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Control of TSH Hypothalamus TRH Anterior Pituitary TSH Thyroid T &T Physiology of Hypothalamus 4 3 and Pitutary gland By Dr Barakat T 4

Gonadotropins • Follicle Stimulating Hormone (FSH) • Luteinizing Hormone (LH) • Chemistry – Glycoprotein • Function – Stimulate function of the reproductive tract Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Gonadotrophins (FSH and LH) Just before puberty two Gonadotrophins are secreted in gradually increasing amounts by the anterior pituitary gland. Its secretion is stimulated by Gonadotrophin releasing hormone (Gn. RH) or luteinizing releasing hormone(LRH) from hypothalamus. Rising level of this hormone during puberty enhances the maturation of reproductive organs. Gonadotrophin is combination of: Follicle stimulating hormone(FSH) Luteinizing hormone(LH) Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Follicle stimulating hormone: In both male and female it stimulates the production of gametes (ova and sperms from ovaries and testis respectively) Luteinizing hormone(LH) IN FEMALES: LH and FSH stimulate the secretion of Oestrogen and Progesterone from corpus luteum during the menstrual cycle. As the level of oestrogen and progesterone rises in blood, secretion of LH and FSH is suppressed. IN MALES: LH also called interstitial cell stimulated releasing hormone (ICSH). of Hypothalamus and It stimulates the. Physiology interstitial cells to secrete Pitutary gland By Dr Barakat

Gonadotropin Control Hypothalamus Gn. RH (FSH Only) Ant. Pituitary FSH LH Gonad Inhibin E 2 & P or T Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Posterior Pituitary Pars Nervosa Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Anatomical Structure • An extension of the hypothalamus • Pituicytes • Axons • Supraoptic n. – ADH • Paraventricular n. – Oxytocin Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Hormones Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Antidiuretic Hormone (ADH, Vasopressin) • Supraoptic nucleus • Chemistry • Receptors – V 1 – V 2 Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Function: • Vasoconstriction – Increase Blood Pressure • Increase permeability of collecting tubule to H 2 O Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Blood Pressure Control of ADH Supraoptic Nucleus Blood Osmolality Blood Pressure Posterior Pituitary Vasoconstriction ADH Blood Vessels Physiology of Hypothalamus and Pitutary gland By Dr Barakat H 2 O Absorption Kidney, Collecting Duct

Diabetes insipidis Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Oxytocin (Pitocin) • Paraventricular nucleus • Chemistry • Receptors – Phosphatidylinositol pathway • Function – Increases frequency and duration of uterine smooth muscle contraction – Stimulates milk “let down. ” Physiology of Hypothalamus and Pitutary gland By Dr Barakat

Positive Feedback Delivery Shuts Control of Oxytocin Loop Shut-Off Suckling On Nipple Off Positive When Child. Loop is Full Feedback Unknown? Hypothalamus Labor Contractions Milk Let-Down Post. Pituitary Mammary Myoepithelial Cells Oxytocin Physiology of Hypothalamus and Pitutary gland By Dr Barakat Uterine Smooth Muscle