Hypothalamus: the master gland Figure 18-7 The Hypophyseal Portal System and the Blood Supply to the Pituitary Gland Supraoptic nuclei Paraventricular nuclei Neurosecretory neurons HYPOTHALAMUS MEDIAN EMINENCE Optic chiasm Mamillary body Superior hypophyseal artery Capillary beds Hypothalamus: the master gland ANTERIOR LOBE OF PITUITARY GLAND Infundibulum Portal vessels Inferior hypophyseal artery POSTERIOR LOBE OF PITUITARY GLAND Endocrine cells Hypophyseal veins p. 605 1

Figure 18-8a Feedback Control of Endocrine Secretion Hypothalamus Releasing hormone (RH) Hormone 1 (from pituitary) Endocrine target organ Hormone 2 (from target organ) TRH TSH Thyroid gland Thyroid hormones RH Pituitary gland CRH ACTH Adrenal cortex Gluco- corticoids Testes Inhibin FSH Inhibin Anterior lobe Ovaries Estrogens GnRH Progestins Ovaries LH Estrogens Hormone 1 Testes Androgens Negative feedback Endocrine organ KEY Stimulation Hormone 2 Inhibition Target cells p. 606 2

Figure 18-8b Feedback Control of Endocrine Secretion Stimulation Stimulation PIH GH–IH Inhibition GH–RH PRF Inhibition Anterior lobe Anterior lobe Epithelia, adipose tissue, liver GH PRL Liver Stimulates mammary glands Somatomedins Stimulates growth of skeletal muscle, cartilage, and many other tissues p. 606 3

Figure 18-9 Pituitary Hormones and Their Targets Hypothalamus KEY TO PITUITARY HORMONES: Direct Control by Nervous System Indirect Control through Release of Regulatory Hormones ACTH Adrenocorticotropic hormone TSH Thyroid-stimulating hormone Regulatory hormones are released into the hypophyseal portal system for delivery to the anterior lobe of the pituitary gland GH Growth hormone PRL Prolactin FSH Follicle-stimulating hormone LH Luteinizing hormone MSH Melanoctye-stimulating hormone ADH Antidiuretic hormone OXT Oxytocin Anterior lobe of pituitary gland Adrenal medulla Adrenal gland ACTH Adrenal cortex GH TSH Epinephrine and norepinephrine Liver MSH Thyroid gland PRL FSH LH Somatomedins Glucocorticoids (cortisol, corticosterone) Melanocytes (uncertain significance in healthy adults) Bone, muscle, other tissues Ovaries of female Testes of male Mammary glands p. 609 Thyroid hormones (T3, T4) Inhibin Testosterone Estrogen Progesterone Inhibin 4

Figure 18-9 Pituitary Hormones and Their Targets KEY TO PITUITARY HORMONES: Direct Release of Hormones ACTH Adrenocorticotropic hormone TSH Thyroid-stimulating hormone Sensory stimulation Osmoreceptor stimulation GH Growth hormone PRL Prolactin FSH Follicle-stimulating hormone LH Luteinizing hormone MSH Melanoctye-stimulating hormone ADH Antidiuretic hormone OXT Oxytocin Posterior lobe of pituitary gland ADH Kidneys OXT Males: Smooth muscle in ductus deferens and prostate gland Females: Uterine smooth muscle and mammary glands p. 609 5

Hypothalamus: the master gland © 2012 Pearson Education, Inc. 1) Direct neuronal innervation of adrenal medulla (come back to) 2) Neuronal innervation of posterior pituitary 3) Portal system release to anterior pituitary 2A) Pathway: Supraoptic neurons → posterior pituitary → ADH → kidneys Affect: ↑ H2O reabsorption in distal convoluted tubule (DCT) & collecting duct (CD) ~5% daily urine output Release stimulated by: ↑ osmotic pressure (↑ solute = ↓ H2O)-detected in hypothalamus ↓ blood pressure &/or volume-detected in heart called osmoreceptors Notes: EtOH ↓ ADH release = ↑ urine output diabetes insipidus: central-don’t make ADH; nephrogenic-don’t respond to ADH 2B) Pathway: Paraventricular neurons → posterior pituitary → oxytocin → uterus/mammary gland [female] OR vas deferens/prostate [male] Affect: female: uterine contractions during labor (+ feedback); contractions during breastfeeding (let down) male: contractions during emission-get sperm out stimulated by: pressure on cervix; nipple stimulation sexual arousal List hormone produced by hypothalamus that goes to anterior pituitary List hormone produced by anterior pituitary List target organ Effects 3A) weirdo-pars intermedia-secretes melanocyte stimulating hormone (MSH); secretion inhibited by dopamine blood levels nearly 0 in humans except: 1) fetal development 2) young children 3) pregnant women 4) disease state also released by skin after sun exposure = paracrine effect The rest follow pathway to pars distalis portion of anterior pituitary 3B) prolactin release factor (dopamine acts as inhibitor) prolactin → breasts→ development and milk production (also involves additional hormones for dev. Esp estrogen) 3C) Gonadotropin Releasing Hormone (GnRH) Lutenizing Hormone (LH) → ovaries → ovulation; estrogen & progesterone release → testes → androgen release Follicle Stimulating Hormone (FSH) → ovaries → estrogen release; follicle development/maturation → testes → sperm development/maturation 3D) Growth Hormone Releasing Hormone (GHRH) & Growth Hormone Inhibiting Hormone (GHIH) Growth Hormone (GH) → kidney/liver → somatomedins → ↑ amino acid uptake/protein synthesis everywhere epithelial/CT → cell division & differentiation adipose → b.d. triglycerides → fatty acid → ATP synthesis liver → b.d. glycogen → ↑ [glucose] in blood all together = growth! depends on genetics and diet too (also increase: exercise, non-REM sleep, thyroid and sex hormones = increase GH release) imbalances: hypo-pituitary dwarfism-small stature, normal brain; Rx inject GH hyper-gigantism before growth plates close; acromegaly after growth plates close 3E) Corticotropic Releasing Hormone (CRH) Adrenocorticotropic Hormone (ACTH) → adrenal cortex → glucocorticoids (cortisol) [come back to w/stress] 3F) Thyrotopin Releasing Hormone (TRH) Thyroid Stimulating Hormone (TSH) → thyroid → T3/T4 p. 619 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

Figure 18-10a The Thyroid Gland Hyoid bone Superior thyroid artery Thyroid cartilage of larynx Internal jugular vein Superior thyroid vein Cricoid cartilage of larynx Common carotid artery Left lobe of thyroid gland Right lobe of thyroid gland Isthmus of thyroid gland Middle thyroid vein Inferior thyroid artery Thyrocervical trunk Inferior thyroid veins Trachea Outline of clavicle p. 611 Outline of sternum Location and anatomy of the thyroid gland 7

Figure 18-10c The Thyroid Gland Capillary Capsule C cell Cuboidal epithelium of follicle Follicle cavities Thyroid follicle Thyroid follicle Thyroglobulin stored in colloid of follicle C cell Follicles of the thyroid gland LM  260 Histological details of the thyroid gland showing thyroid follicles and both of the cell types in the follicular epithelium ATLAS: Plate 18c p. 611 8

Figure 18-11a The Thyroid Follicles cavity Thyroglobulin (contains T3 and T4) FOLLICLE CAVITY Endocytosis Thyroglobulin Iodide (I+) Lysosomal digestion Other amino acids Tyrosine T4 T3 Diffusion Diffusion TSH- sensitive ion pump FOLLICLE CELL CAPILLARY Iodide (I–) TBG, transthryretin, or albumin T4 & T3 p. 612 The synthesis, storage, and secretion of thyroid hormones. 9

Figure 18-11b The Thyroid Follicles Hypothalamus releases TRH Homeostasis Disturbed Decreased T3 and T4 concentrations in blood or low body temperature TRH Anterior lobe Pituitary gland HOMEOSTASIS Normal T3 and T4 concentrations, normal body temperature Anterior lobe TSH Homeostasis Restored Increased T3 and T4 concentrations in blood Thyroid gland Thyroid follicles release T3 and T4 p. 612 The regulation of thyroid secretion 10

© 2012 Pearson Education, Inc. 601 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2012 Pearson Education, Inc.

© 2012 Pearson Education, Inc. The Thyroid Gland Very nice chart! Regulation usually negative ↑ T3 & T4 = ↓ TRH Extremely cold weather = ↑ TRH [in kids] Extreme anxiety/excitement = ↓ TRH [counteract sympathetic NS stimulation] Imbalances: hypo-extreme = cretinism mental & physical retardation (diff from ↓ GH) hypo-not so bad = myxedema low BMR = lethargic, confused generalized edema, increased cholesterol hyper-extreme = thyrotoxicosis >160% normal BMR- hungry, weight loss, nervous/edgy Grave’s disease: immune system antibodies to receptor for TSH therefore chronically stimulate TSH receptors = ↑ production of T3 & T4 p. 613 Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2012 Pearson Education, Inc.

Figure 18-10c The Thyroid Gland Capillary Capsule C cell Cuboidal epithelium of follicle Follicle cavities Thyroid follicle Thyroid follicle Thyroglobulin stored in colloid of follicle C cell Follicles of the thyroid gland LM  260 Histological details of the thyroid gland showing thyroid follicles and both of the cell types in the follicular epithelium ATLAS: Plate 18c p. 611 13

Figure 18-12a The Parathyroid Glands Left lobe of thyroid gland Parathyroid glands Posterior view of the thyroid gland showing the parathyroid glands. p. 614 14

Figure 18-12c The Parathyroid Glands (chief) cells Oxyphil cells Parathyroid cells and oxyphil cells LM  600 Parathyroid gland cells p. 614 15

Figure 18-13 The Homeostatic Regulation of Calcium Ion Concentrations Increased excretion of calcium by kidneys Thyroid gland produces calcitonin Calcium deposition in bone HOMEOSTASIS RESTORED HOMEOSTASIS DISTURBED Rising levels of blood calcium Blood calcium levels decline Rising calcium levels in blood HOMEOSTASIS Normal blood calcium levels (8.5–11 mg/dL) p. 615 16

Figure 18-13 The Homeostatic Regulation of Calcium Ion Concentrations HOMEOSTASIS Normal blood calcium levels (8.5–11 mg/dL) Falling levels of blood calcium HOMEOSTASIS DISTURBED HOMEOSTASIS RESTORED Falling calcium levels in blood Blood calcium levels increase Increased reabsorption of calcium by kidneys Parathyroid glands secrete parathyroid hormone (PTH) Calcium release from bone Increased calcitriol production causes Ca2+ absorption by digestive system p. 615 17

Figure 18-15 The Pineal Gland Pinealocytes p. 619 Pineal gland LM  450 18

© 2012 Pearson Education, Inc. Pineal gland-epithalamus-secretes melatonin Serotonin converted to melatonin during the dark part of day This conversion is inhibited during the day SAD due to increased melatonin production Inhibits puberty in humans; levels fall just before puberty; tumors that prevent it’s release lead to precocious puberty Involved with circadian and annual rhythms Acts as an anti-oxidant in the CNS to prevent damage to tissue Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings © 2012 Pearson Education, Inc.