Figure 16 1 Location of selected endocrine organs

Figure 16. 1 Location of selected endocrine organs of the body. Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid glands (on dorsal aspect of thyroid gland) Thymus Adrenal glands Pancreas Gonads • Ovary (female) • Testis (male) © 2013 Pearson Education, Inc.

Tricks for learning • • • Make lists Draw flow charts Make flash cards Use Mastering A and P Review, review © 2013 Pearson Education, Inc.

Figure 16. 2 Cyclic AMP second-messenger mechanism of water-soluble hormones. Recall from Chapter 3 that G protein signaling mechanisms are like a molecular relay race. Hormone Receptor G protein Enzyme 2 nd (1 st messenger) messenger 1 Hormone (1 st messenger) binds receptor. Extracellular fluid Adenylate cyclase G protein (Gs) Receptor 5 c. AMP activates protein kinases. c. AMP GTP ATP GDP Inactive protein kinase GTP Active protein kinase Triggers responses of target cell (activates enzymes, stimulates cellular secretion, opens ion channel, etc. ) Cytoplasm 2 Receptor activates G protein (Gs). © 2013 Pearson Education, Inc. 3 G protein activates adenylate cyclase. 4 Adenylate cyclase converts ATP to c. AMP (2 nd messenger).

Figure 16. 3 Direct gene activation mechanism of lipid-soluble hormones. Extracellular fluid Steroid hormone Plasma membrane Cytoplasm Receptor protein Nucleus 1 The steroid hormone diffuses through the plasma membrane and binds an intracellular receptor. Receptorhormone complex 2 The receptorhormone complex enters the nucleus. Receptor Binding region DNA m. RNA 3 The receptor- hormone complex binds a specific DNA region. 4 Binding initiates transcription of the gene to m. RNA. 5 The m. RNA directs protein synthesis. New protein © 2013 Pearson Education, Inc.

Figure 16. 4 Three types of endocrine gland stimuli. (a) Humoral Stimulus Hormone release caused by altered levels of certain critical ions or nutrients. (b) Neural Stimulus Hormone release caused by neural input. (c) Hormonal Stimulus Hormone release caused by another hormone (a tropic hormone). Hypothalamus CNS (spinal cord) Capillary (low Ca 2+ in blood) Thyroid gland (posterior view) Parathyroid glands Preganglionic sympathetic fibers Anterior pituitary gland Thyroid gland Adrenal cortex Gonad (Testis) Medulla of adrenal gland Parathyroid glands PTH Capillary Stimulus: Low concentration of Ca 2+ in capillary blood. Response: Parathyroid glands secrete parathyroid hormone (PTH), which increases blood Ca 2+. Stimulus: Action potentials in preganglionic sympathetic fibers to adrenal medulla. Response: Adrenal medulla cells secrete epinephrine and norepinephrine. © 2013 Pearson Education, Inc. Stimulus: Hormones from hypothalamus. Response: Anterior pituitary gland secretes hormones that stimulate other endocrine glands to secrete hormones.

Figure 16. 4 a Three types of endocrine gland stimuli. Humoral Stimulus Hormone release caused by altered levels of certain critical ions or nutrients. Capillary (low Ca 2+ in blood) Thyroid gland (posterior view) Parathyroid glands PTH Stimulus: Low concentration of Ca 2+ in capillary blood. Response: Parathyroid glands secrete parathyroid hormone (PTH), which increases blood Ca 2+. © 2013 Pearson Education, Inc.

Figure 16. 4 b Three types of endocrine gland stimuli. Neural Stimulus Hormone release caused by neural input. CNS (spinal cord) Preganglionic sympathetic fibers Medulla of adrenal gland Capillary Stimulus: Action potentials in preganglionic sympathetic fibers to adrenal medulla. Response: Adrenal medulla cells secrete epinephrine and norepinephrine. © 2013 Pearson Education, Inc.

Figure 16. 4 c Three types of endocrine gland stimuli. Hormonal Stimulus Hormone release caused by another hormone (a tropic hormone). Hypothalamus Anterior pituitary gland Thyroid gland Adrenal Gonad cortex (Testis) Stimulus: Hormones from hypothalamus. Response: Anterior pituitary gland secretes hormones that stimulate other endocrine glands to secrete hormones. © 2013 Pearson Education, Inc.

Figure 16. 5 The hypothalamus controls release of hormones from the pituitary gland in two different ways. Anterior Pituitary: Posterior Pituitary: Paraventricular nucleus Hypothalamus Posterior lobe of pituitary Optic chiasma Infundibulum (connecting stalk) Hypothalamichypophyseal tract Axon terminals Posterior lobe of pituitary Supraoptic nucleus Inferior hypophyseal artery 1 Hypothalamic neurons synthesize oxytocin or antidiuretic hormone (ADH). Anterior lobe Superior of pituitary hypophyseal artery 2 Hypothalamic hormones travel through portal veins to 2 Oxytocin and ADH are the anterior pituitary where transported down the axons of they stimulate or inhibit relethe hypothalamic- hypophyseal ase of hormones made in the tract to the posterior pituitary. anterior pituitary. 3 In response to releasing 3 Oxytocin and ADH are stored hormones, the anterior pituitary in axon terminals in the secretes hormones into the posterior pituitary. secondary capillary plexus. This in turn empties into the general circulation. Oxytocin 4 When associated GH, TSH, ACTH, hypothalamic neurons fire, ADH FSH, LH, PRL action potentials arriving at the Anterior lobe axon terminals cause oxytocin of pituitary or ADH to be released into the blood. © 2013 Pearson Education, Inc. Hypothalamus Hypothalamic neurons synthesize GHRH, GHIH, TRH, CRH, Gn. RH, PIH. 1 When appropriately stimulated, hypothalamic neurons secrete releasing or inhibiting hormones into the primary capillary plexus. Hypophyseal portal system • Primary capillary plexus • Hypophyseal portal veins • Secondary capillary plexus A portal system is two capillary plexuses (beds) connected by veins.

Figure 16. 5 The hypothalamus controls release of hormones from the pituitary gland in two different ways. (1 of 2) Posterior Pituitary: Paraventricular nucleus Hypothalamus Posterior lobe of pituitary Optic chiasma Infundibulum (connecting stalk) Hypothalamichypophyseal tract Supraoptic nucleus Inferior hypophyseal artery Axon terminals 2 Oxytocin and ADH are transported down the axons of the hypothalamic- hypophyseal tract to the posterior pituitary. 3 Oxytocin and ADH are stored in axon terminals in the posterior pituitary. Posterior lobe of pituitary Oxytocin ADH © 2013 Pearson Education, Inc. 1 Hypothalamic neurons synthesize oxytocin or antidiuretic hormone (ADH). 4 When hypothalamic neurons fire, action potentials arriving at the axon terminals cause oxytocin or ADH to be released into the blood.

Figure 16. 5 The hypothalamus controls release of hormones from the pituitary gland in two different ways. (2 of 2) Anterior Pituitary: Hypothalamus Anterior lobe of pituitary Superior hypophyseal artery 2 Hypothalamic hormones travel through portal veins to the anterior pituitary where they stimulate or inhibit release of hormones made in the anterior pituitary. 3 In response to releasing hormones, the anterior pituitary secretes hormones into the secondary capillary plexus. This in turn empties into the general circulation. GH, TSH, ACTH, FSH, LH, PRL Anterior lobe of pituitary © 2013 Pearson Education, Inc. Hypothalamic neurons synthesize GHRH, GHIH, TRH, CRH, Gn. RH, PIH. 1 When appropriately stimulated, hypothalamic neurons secrete releasing or inhibiting hormones into the primary capillary plexus. Hypophyseal portal system • Primary capillary plexus • Hypophyseal portal veins • Secondary capillary plexus A portal system is two capillary plexuses (beds) connected by veins.

Table 16. 1 Pituitary Hormones: Summary of Regulation and Effects (1 of 4) © 2013 Pearson Education, Inc.

Table 16. 1 Pituitary Hormones: Summary of Regulation and Effects (2 of 4) © 2013 Pearson Education, Inc.

Table 16. 1 Pituitary Hormones: Summary of Regulation and Effects (3 of 4) © 2013 Pearson Education, Inc.

Table 16. 1 Pituitary Hormones: Summary of Regulation and Effects (4 of 4) © 2013 Pearson Education, Inc.

Figure 16. 6 Growth-promoting and metabolic actions of growth hormone (GH). Feedback Inhibits GHRH release Stimulates GHIH release Anterior pituitary Hypothalamus secretes growth hormone–releasing hormone (GHRH), and GHIH (somatostatin) Inhibits GH synthesis and release Growth hormone (GH) Direct actions Indirect actions (metabolic, anti-insulin) (growthpromoting) Liver and other tissues Produce Insulin-like growth factors (IGFs) Effects Skeletal Extraskeletal Fat metabolism Carbohydrate metabolism Increases, stimulates Reduces, inhibits Increased cartilage formation and skeletal growth Increased protein synthesis, and cell growth and proliferation © 2013 Pearson Education, Increased fat breakdown and release Increased blood glucose and other anti-insulin effects Initial stimulus Physiological response Result

Figure 16. 7 Disorders of pituitary growth hormone. © 2013 Pearson Education, Inc.

Figure 16. 8 Regulation of thyroid hormone secretion. Hypothalamus TRH Anterior pituitary TSH Thyroid gland Thyroid hormones Target cells © 2013 Pearson Education, Inc. Stimulates Inhibits

Figure 16. 9 The thyroid gland. Hyoid bone Thyroid cartilage Common carotid artery Inferior thyroid artery Trachea Epiglottis Colloid-filled follicles Follicular cells Superior thyroid artery Isthmus of thyroid gland Left subclavian artery Left lateral lobe of thyroid gland Aorta Parafollicular cells Gross anatomy of the thyroid gland, anterior view © 2013 Pearson Education, Inc. Photomicrograph of thyroid gland follicles (145 x)

Table 16. 2 Major Effects of Thyroid Hormone (T 4 and T 3) in the Body (1 of 2) © 2013 Pearson Education, Inc.

Table 16. 2 Major Effects of Thyroid Hormone (T 4 and T 3) in the Body (2 of 2) © 2013 Pearson Education, Inc.

Figure 16. 10 Synthesis of thyroid hormone. Thyroid follicular cells Colloid 1 Thyroglobulin is synthesized and discharged into the follicle lumen. Tyrosines (part of thyroglobulin molecule) Capillary 4 Iodine is attached to tyrosine in colloid, forming DIT and MIT. Golgi apparatus Rough ER Iodine 3 Iodide is oxidized to iodine. 2 Iodide (I–) is trapped (actively transported in). Iodide (I−) T 4 T 3 Lysosome DIT MIT Thyroglobulin colloid 5 Iodinated tyrosines are linked together to form T 3 and T 4 T 3 6 Thyroglobulin colloid is endocytosed and combined with a lysosome. 7 Lysosomal enzymes cleave T 4 and T 3 from thyroglobulin and hormones diffuse into bloodstream. To peripheral tissues © 2013 Pearson Education, Inc. Colloid in lumen of follicle

Figure 16. 11 Thyroid disorders. © 2013 Pearson Education, Inc.

Figure 16. 13 Effects of parathyroid hormone on bone, the kidneys, and the intestine. Hypocalcemia (low blood Ca 2+) PTH release from parathyroid gland Osteoclast activity in bone causes Ca 2+ and PO 43 - release into blood Ca 2+ reabsorption in kidney tubule Activation of vitamin D by kidney Ca 2+ absorption from food in small intestine Ca 2+ in blood Initial stimulus Physiological response Result © 2013 Pearson Education, Inc.

Figure 16. 14 Microscopic structure of the adrenal gland. Hormones secreted Zona glomerulosa Aldosterone Zona fasciculata Cortex Adrenal gland • Medulla • Cortex Capsule Cortisol androgens Kidney Medulla Zona reticularis Adrenal medulla Drawing of the histology of the adrenal cortex and a portion of the adrenal medulla © 2013 Pearson Education, Inc. Epinephrine and norepinephrine Photomicrograph (115 x)

Figure 16. 14 a Microscopic structure of the adrenal gland. Capsule Zona glomerulosa Cortex Adrenal gland • Medulla • Cortex Zona fasciculata Kidney Medulla Zona reticularis © 2013 Pearson Education, Inc. Adrenal medulla Drawing of the histology of the adrenal cortex and a portion of the adrenal medulla

Figure 16. 14 b Microscopic structure of the adrenal gland. Capsule Hormones secreted Zona glomerulosa Aldosterone Zona fasciculata Cortisol androgens Zona reticularis Adrenal medulla Epinephrine and norepinephrine Photomicrograph (115 x) © 2013 Pearson Education, Inc.

Figure 16. 15 Major mechanisms controlling aldosterone release from the adrenal cortex. Primary regulators Blood volume and/or blood pressure K+ in blood Other factors Stress Blood pressure and/or blood volume Hypothalamus Kidney Heart CRH Renin Direct stimulating effect Initiates cascade that produces Anterior pituitary Atrial natriuretic peptide (ANP) ACTH Angiotensin II Inhibitory effect Zona glomerulosa of adrenal cortex Enhanced secretion of aldosterone Targets kidney tubules Absorption of Na+ and water; increased K+ excretion Blood volume and/or blood pressure © 2013 Pearson Education, Inc.

Figure 16. 16 The effects of excess glucocorticoid. Patient before onset. © 2013 Pearson Education, Inc. Same patient with Cushing’s syndrome. The white arrow shows the characteristic “buffalo hump” of fat on the upper back.

Table 16. 3 Adrenal Gland Hormones: Summary of Regulation and Effects © 2013 Pearson Education, Inc.

Figure 16. 17 Stress and the adrenal gland. Short-term stress Prolonged stress Stress Nerve impulses Hypothalamus CRH (corticotropinreleasing hormone) Spinal cord Corticotropic cells of anterior pituitary To target in blood Preganglionic sympathetic fibers Adrenal medulla (secretes amino acid– based hormones) Catecholamines (epinephrine and norepinephrine) Short-term stress response • Heart rate increases • Blood pressure increases • Bronchioles dilate • Liver converts glycogen to glucose and releases glucose to blood • Blood flow changes, reducing digestive system activity and urine output • Metabolic rate increases © 2013 Pearson Education, Inc. ACTH Mineralocorticoids Adrenal cortex (secretes steroid hormones) Glucocorticoids Long-term stress response • Kidneys retain • Proteins and fats converted sodium and water to glucose or broken down for energy • Blood volume and • Blood glucose increases blood pressure • Immune system rise supressed

Figure 16. 18 Photomicrograph of differentially stained pancreatic tissue. Pancreatic islet • (Glucagonproducing) cells • (Insulinproducing) cells Pancreatic acinar cells (exocrine) © 2013 Pearson Education, Inc.

Figure 16. 19 Insulin and glucagon from the pancreas regulate blood glucose levels. Stimulates glucose uptake by cells Tissue cells Insulin Stimulates glycogen formationw Pancreas Glucose Glycogen Blood glucose falls to normal range. Liver IMB AL Stimulus Blood glucose level AN CE BALANCE: Normal blood glucose level (about 90 mg/100 ml) Stimulus IMB AL Blood glucose rises to normal range. AN CE Blood glucose level Pancreas Glucose Glycogen Liver © 2013 Pearson Education, Inc. Stimulates glycogen breakdown Glucagon

Table 16. 4 Symptoms of Insulin Deficit (Diabetes Mellitus) © 2013 Pearson Education, Inc.

Table 16. 5 Selected Examples of Hormones Produced by Organs Other Than the Major Endocrine Organs (1 of 2) © 2013 Pearson Education, Inc.

Table 16. 5 Selected Examples of Hormones Produced by Organs Other Than the Major Endocrine Organs (2 of 2) © 2013 Pearson Education, Inc.