PITUITARY GLAND HYPOTHALAMUS Anatomical Relations Pituitary Sella Turcica

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PITUITARY GLAND HYPOTHALAMUS

PITUITARY GLAND HYPOTHALAMUS

Anatomical Relations • • • Pituitary Sella Turcica Optic Chiasm Median Eminence Mamillary Body

Anatomical Relations • • • Pituitary Sella Turcica Optic Chiasm Median Eminence Mamillary Body Cavernous Sinus (not visible)

Subdivisions of the Pituitary (Hypophysis) • Adenohypophysis (Anterior Pituitary) – Pars Distalis – Pars

Subdivisions of the Pituitary (Hypophysis) • Adenohypophysis (Anterior Pituitary) – Pars Distalis – Pars Intermedia – Pars Tuberalis • Neurohypophysis (Posterior Pituitary) – Pars Nervosa – Infundibular Stalk

Adenohypophysis

Adenohypophysis

Pars Distalis

Pars Distalis

Cells: • Acidophils – Somatotroph – Lactotroph • Basophils – Gonadotrophs – Thyrotrophs •

Cells: • Acidophils – Somatotroph – Lactotroph • Basophils – Gonadotrophs – Thyrotrophs • Corticotrophs (can’t distinguish) • Chromophobes

Hormones • Prolactin/Growth Hormone Family – Prolactin – Growth Hormone • Glycoprotein Family –

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

Prohormones • Many small hormones, especially peptide hormones, are synthesized as part of a

Prohormones • Many small hormones, especially peptide hormones, are synthesized as part of a larger peptide. • The large peptide is called a prohormone • The active hormone is cut of the larger prohormone by an enzyme. • The prohormone generally is not active.

POMC

POMC

Pars Intermedia • MSH – Pro-opiomelanocortin Family – Alpha – Beta • Also in

Pars Intermedia • MSH – Pro-opiomelanocortin Family – Alpha – Beta • Also in Hypothalamus – Involved in regulating metabolism and appetite

Pars Tuberalis

Pars Tuberalis

Hypothalamus

Hypothalamus

Hypothalamo-hypophyseal Portal System • Superior hypophyseal artery • Portal Vessels • Capillary Bed of

Hypothalamo-hypophyseal Portal System • Superior hypophyseal artery • Portal Vessels • Capillary Bed of Pars Distalis

Hypothalamic Releasing Hormones • • • Thyrotropin Releasing Hormone (TRH) Corticotropin Releasing Hormone (CRH)

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)

Feedback Control of Anterior Pituitary • Long Loop • Short Loop • Ultrashort Loop

Feedback Control of Anterior Pituitary • Long Loop • Short Loop • Ultrashort Loop • Amplitude • Frequency

Pathologies • Hypersecretion • Hyposecretion • Classification – Primary (Pituitary’s Target Gland) – Secondary

Pathologies • Hypersecretion • Hyposecretion • Classification – Primary (Pituitary’s Target Gland) – Secondary (Pituitary) – Tertiary (Hypothalamus) • Pituitary adenomas

Growth Hormone (GH)

Growth Hormone (GH)

Chemistry • • Single chain protein, 191 amino acids MW 21, 500 2 -disulfide

Chemistry • • Single chain protein, 191 amino acids MW 21, 500 2 -disulfide bridges Synthesized as part of a larger protein, pre. GH (MW 28, 000)

Function • Stimulate Secretion of Insulin-like Growth Factor 1 (IGF-1) • Increase linear growth

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

GHRH Control of Secretion: Somatostatin (GHIH) Stimulates • GRH Inhibits the Secretion of GH

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 Secretion of GH

Feedback • GH--Short Loop • IGFs--Long Loop • Metabolic control – Blood Glucose –

Feedback • GH--Short Loop • IGFs--Long Loop • Metabolic control – Blood Glucose – Blood Fatty Acids – Blood Amino Acids • Neural regulation – – Diurnal Rhythms Deep Sleep Stress Exercise

Long-Loop Diurnal Feedback Rhythms Exercise Sleep Regulation Stress GH Short-Loop Somatostatin Feedback Hypothalamus Serum:

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 Liver IGF 1 GH Serum: Glu. Lipids Amino Acids Other Target Tissues

Pathologies

Pathologies

Hypersecretion

Hypersecretion

Gigantism

Gigantism

Acromegaly

Acromegaly

Glucose Intolerance • A form of Diabetes • Caused by Hyperglycemia • Leads to

Glucose Intolerance • A form of Diabetes • Caused by Hyperglycemia • Leads to Type II Diabetes

Hyposecretion

Hyposecretion

Dwarfism

Dwarfism

Prolactin (PRL) • Chemistry • Function: • Control of Secretion

Prolactin (PRL) • Chemistry • Function: • Control of Secretion

Control of PRL Baby Suckles Nipple Baby Weaned Sensory Impulses to Hypothalamus Milk Production

Control of PRL Baby Suckles Nipple Baby Weaned Sensory Impulses to Hypothalamus Milk Production Dopamine Secretion Prolactin

Adrenocorticotropic Hormone (ACTH) • • Chemistry Biosynthesis Function Control of Secretion

Adrenocorticotropic Hormone (ACTH) • • Chemistry Biosynthesis Function Control of Secretion

Control of ACTH Stress Sleep Hypothalamus CRH Ant. Pituitary ACTH Adrenal Cortex Glucocorticoids

Control of ACTH Stress Sleep Hypothalamus CRH Ant. Pituitary ACTH Adrenal Cortex Glucocorticoids

Thyroid Stimulating Hormone (TSH) • Chemistry – Glycoprotein – 2 Chains • Function –

Thyroid Stimulating Hormone (TSH) • Chemistry – Glycoprotein – 2 Chains • Function – Stimulate production of thyroid hormone (T 4 & T 3)

Control of TSH Hypothalamus TRH Anterior Pituitary TSH Thyroid T 4 & T 3

Control of TSH Hypothalamus TRH Anterior Pituitary TSH Thyroid T 4 & T 3 T 4

Gonadotropins • Follicle Stimulating Hormone (FSH) • Luteinizing Hormone (LH) • Chemistry – Glycoprotein

Gonadotropins • Follicle Stimulating Hormone (FSH) • Luteinizing Hormone (LH) • Chemistry – Glycoprotein • Function – Stimulate function of the reproductive tract

Gonadotropin Control Hypothalamus Gn. RH (FSH Only) Ant. Pituitary FSH LH Gonad Inhibin E

Gonadotropin Control Hypothalamus Gn. RH (FSH Only) Ant. Pituitary FSH LH Gonad Inhibin E 2 & P or T

Posterior Pituitary Pars Nervosa

Posterior Pituitary Pars Nervosa

Anatomical Structure • An extension of the hypothalamus • Pituicytes • Axons • Supraoptic

Anatomical Structure • An extension of the hypothalamus • Pituicytes • Axons • Supraoptic n. – ADH • Paraventricular n. – Oxytocin

Hormones

Hormones

Antidiuretic Hormone (ADH, Vasopressin) • Supraoptic nucleus • Chemistry • Receptors – V 1

Antidiuretic Hormone (ADH, Vasopressin) • Supraoptic nucleus • Chemistry • Receptors – V 1 – V 2

Function: • Vasoconstriction – Increase Blood Pressure • Increase permeability of collecting tubule to

Function: • Vasoconstriction – Increase Blood Pressure • Increase permeability of collecting tubule to H 2 O

Blood Pressure Control of ADH Blood Pressure Vasoconstriction Blood Vessels Supraoptic Nucleus Blood Osmolality

Blood Pressure Control of ADH Blood Pressure Vasoconstriction Blood Vessels Supraoptic Nucleus Blood Osmolality Posterior Pituitary ADH H 2 O Absorption Kidney, Collecting Duct

Diabetes insipidis

Diabetes insipidis

Oxytocin (Pitocin) • Paraventricular nucleus • Chemistry • Receptors – Phosphatidylinositol pathway • Function

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

Positive Feedback Delivery Shuts Control of Oxytocin Loop Shut-Off Suckling On Nipple Off Positive

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 Uterine Smooth Muscle