Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Principles of Anatomy and Physiology Thirteenth Edition Gerard J. Tortora • Bryan H. Derrickson Chapter 18 The Endocrine System Copyright © 2012 by John Wiley & Sons, Inc. PINEAL GLAND HYPOTHALAMUS Thyroid gland PARATHYROID GLANDS PITUITARY GLAND Trachea THYROID GLAND Trachea PARATHYROID GLANDS (behind thyroid glands) SKIN THYMUS Lung HEART LIVER STOMACH ADRENAL GLANDS KIDNEY Uterus PANCREAS OVARY SMALL INTESTINE Female Scrotum TESTES Male Endocrine cell Circulating hormone Blood capillary Hormone receptor Distant target cells (a) Circulating hormones Paracrine receptor Paracrine Paracrine cell Nearby target cell Autocrine cell Autocrine (b) Local hormones (paracrines and autocrines) Autocrine receptor Steroid hormones Aldosterone Thyroid hormones Triiodothyronine (T3) Amines Norepinephrine Peptides and proteins Oxytocin Eicosanoids A leukotriene (LTB4) Free hormone Transport protein 2 Activated receptor– hormone complex alters gene expression Cytosol Blood capillary 1 Lipid-soluble hormone diffuses into cell Nucleus Receptor DNA mRNA Ribosome 3 Newly Formed mRNA directs synthesis of specific proteins on ribosomes New protein 4 New proteins alter cell's activity Target cell Blood capillary Binding of hormone (first messenger) to its receptor activates G protein, which activates adenylate cyclase 1 Water-soluble hormone Adenylate cyclase Receptor Second messenger G protein ATP cAMP 2 Activated adenylate cyclase converts ATP to cAMP 6 Phosphodiesterase Protein kinases 3 cAMP serves as a Activated inactivates cAMP second messenger protein to activate protein kinases kinases 4 Activated protein Protein kinases phosphorylate ATP cellular proteins ADP Protein - P 5 Millions of phosphorylated proteins cause reactions that produce physiological responses Target cell Infundibulum Hypothalamus POSTERIOR PITUITARY ANTERIOR PITUITARY Pituitary gland Sagittal section of pituitary gland Primary plexus of hypophyseal portal system Infundibulum HYPOTHALAMUS Median eminence Superior hypophyseal artery Posterior hypophyseal veins Hypophyseal portal veins Sphenoid bone POSTERIOR PITUITARY ANTERIOR PITUITARY Capillary plexus of infundibular process Secondary plexus of hypophyseal portal system Hypophyseal fossa Anterior hypophyseal veins POSTERIOR ANTERIOR Inferior hypophyseal artery (a) Relationship of hypothalamus to pituitary gland Hypothalamic neurosecretory cell Primary plexus of hypophyseal portal system Hypophyseal portal veins (b) Path of releasing and inhibiting hormones Corticotroph Somatotroph Thyrotroph Lactotroph Gonadotroph LM all about 65x (c) Histology of anterior pituitary Corticotropin-releasing hormone (CRH) Hypothalamus CRH stimulates release of corticotropin (ACTH) Anterior pituitary Corticotropin stimulates secretion of cortisol by adrenal cortex Adrenal cortex Cortisol Corticotropin (ACTH) Elevated cortisol inhibits release of CRH by hypothalamic neurosecretory cells Elevated cortisol inhibits release of corticotropin by anterior pituitary corticotrophs 1 Low blood glucose 6 High blood glucose (hypoglycemia) stimulates release of (hyperglycemia) stimulates release of GHRH GHIH 2 GHRH stimulates 7 secretion of hGH by somatotrophs GHIH inhibits secretion of hGH by somatotrophs hGH Anterior pituitary 3 hGH and IGFs speed 8 A low level of hGH and up breakdown of liver glycogen into glucose, which enters the blood more rapidly 4 Blood glucose level rises to normal (about 90 mg/100 mL) 5 If blood glucose continues to increase, hyperglycemia inhibits release of GHRH IGFs decreases the rate of glycogen breakdown in the liver and glucose enters the blood more slowly 9 Blood glucose level falls to normal (about 90 mg/100 mL) 10 If blood glucose continues to decrease, hypoglycemia inhibits release of GHIH Human growth hormone (hGH), also known as somatotropin Luteinizing hormone (LH) Ovaries Testes Liver (and other tissues) Prolactin (PRL) Thyroid-stimulating hormone (TSH), also known as thyrotropin Mammary glands Adrenocorticotropic hormone (ACTH), also known as corticotropin Thyroid gland Adrenal cortex Follicle-stimulating hormone (FSH) Melanocyte-stimulating hormone (MSH) Ovaries Testes Brain Hypothalamus Neurosecretory cells Pituitary gland HYPOTHALAMUS Optic chiasm Capillary plexus of the posterior pituitary Infundibulum Axons of neurosecretory cells Axon terminal POSTERIOR PITUITARY ANTERIOR PITUITARY 1 High blood osmotic pressure 5 Low blood osmotic pressure stimulates hypothalamic osmoreceptors inhibits hypothalamic osmoreceptors Osmoreceptors 2 Osmoreceptors activate neurosecretory cells that synthesize and release ADH 6 Inhibition of osmoreceptors reduces or stops ADH secretion Hypothalamus 3 Nerve impulses liberate ADH from axon terminals in posterior pituitary into bloodstream ADH Target tissues 4 Kidneys retain more water, which decreases urine output Sudoriferous (sweat) glands decrease water loss by perspiration from skin Arterioles constrict, which increases blood pressure Oxytocin (OT) Uterus Mammary glands Antidiuretic hormone (ADH) or vasopressin Kidneys Sudoriferous (sweat) glands Arterioles Hyoid bone Superior thyroid artery Thyroid gland Trachea Superior thyroid vein Pyramidal lobe of thyroid gland Thyroid cartilage of larynx RIGHT LATERAL LOBE OF THYROID GLAND LEFT LATERAL LOBE OF THYROID GLAND Middle thyroid vein Common carotid artery Inferior thyroid artery ISTHMUS OF THYROID GLAND Vagus (X) nerve Internal jugular vein Subclavian artery Trachea Inferior thyroid veins Sternum (a) Anterior view of thyroid gland Parafollicular (C) cell Follicular cell Thyroid follicle Thyroglobulin (TGB) (colloid) Basement membrane LM 500x (b) Thyroid follicles LEFT LATERAL LOBE RIGHT LATERAL LOBE ISTHMUS (c) Anterior view of thyroid gland Thyroid cartilage of larynx Cricoid cartilage of larynx RIGHT LATERAL LOBE OF THYROID GLAND LEFT LATERAL LOBE OF THYROID GLAND ISTHMUS OF THYROID GLAND Trachea Right lung Arch of aorta (d) Anterior view Portion of thyroid follicle Follicular cell Colloid 4 Iodination of tyrosine Blood capillary 5 Coupling of T1 and T2 Tyrosine T1 T2 T4 3 Oxidation of iodide T3 Colloid I2 TGB 6 Pinocytosis and digestion of colloid Secretory vesicles Lysosome Golgi complex I– I– I– I– I– I– I– I– 2 Synthesis of TGB Rough ER 1 Iodide I– I– Key: T3 T 4 7 Secretion of thyroid hormones trapping I– T3 T4 T3 TBG Blood T TBG 4 plasma I– = Iodide; I2 = Iodine TGB = thyroglobulin TBG = thyroxine-binding globulin 8 Transport in blood Blood capillary 1 Low blood levels of T3 and T4 or low metabolic rate stimulates release of Hypothalamus TRH 2 TRH, carried by hypophyseal portal veins to anterior pituitary, stimulates release of TSH by thyrotrophs 5 Elevated T3 inhibits release of TRH and TSH (negative feedback) TSH 3 TSH released into blood stimulates thyroid follicular cells Anterior pituitary 4 T3 and T4 released into Thyroid follicle blood by follicular cells T3 (triiodothyronine) and T4 (thyroxine) or thyroid hormones from follicular cells Thyroid follicle Follicular cells Blood vessel Calcitonin (CT) from parafollicular cells Thyroid follicle Parafollicular cells Parathyroid glands (behind thyroid gland) Trachea Right internal jugular vein Right common carotid artery Middle cervical sympathetic ganglion Thyroid gland LEFT SUPERIOR PARATHYROID GLAND RIGHT SUPERIOR PARATHYROID GLAND Esophagus Inferior cervical sympathetic ganglion LEFT INFERIOR PARATHYROID GLAND RIGHT INFERIOR PARATHYROID GLAND Left inferior thyroid artery Vagus (X) nerve Left subclavian artery Right brachiocephalic vein Brachiocephalic trunk Left subclavian vein Left common carotid artery Trachea (a) Posterior view Venule Capillary Arteriole Chief cell Oxyphil cell (b) Parathyroid gland LM 240x Capsule Parathyroid Thyroid Follicular cell Parafollicular cell Chief cell Oxyphil cell Thyroid gland Parathyroid gland Blood vessel (c) Portion of thyroid gland (left) and parathyroid gland (right) PARATHYROID GLAND Thyroid gland PARATHYROID GLAND (d) Posterior view of parathyroid glands 1 High level of Ca2+ in blood stimulates thyroid gland parafollicular cells to release more CT. 3 Low level of Ca2+ in blood stimulates parathyroid gland chief cells to release more PTH. 6 CALCITRIOL stimulates increased absorption of Ca2+ from foods, which increases blood Ca2+ level. 5 PTH also stimulates the kidneys to release CALCITRIOL. 4 PARATHYROID HORMONE (PTH) Ca2+ from promotes release of bone extracellular matrix into blood and slows loss of Ca2+ in urine, thus increasing blood Ca2+ level. 2 CALCITONIN inhibits osteoclasts, thus decreasing blood Ca2+ level. Parathyroid hormone (PTH) from chief cells Chief cell Adrenal glands Inferior phrenic arteries Kidney Right superior suprarenal arteries LEFT ADRENAL GLAND Celiac trunk RIGHT ADRENAL GLAND Left middle suprarenal artery Right middle suprarenal artery Left inferior suprarenal artery Right inferior suprarenal artery Left suprarenal vein Right renal artery Left renal vein Left renal artery Right renal vein Superior mesenteric artery Inferior vena cava Abdominal aorta (a) Anterior view CAPSULE ADRENAL CORTEX ADRENAL MEDULLA (b) Section through left adrenal gland ADRENAL GLAND Kidney (c) Anterior view of adrenal gland and kidney Capsule Adrenal cortex: Zona glomerulosa secretes mineralocorticoids, mainly aldosterone Zona fasciculata secretes glucocorticoids, mainly cortisol Zona reticularis secretes androgens Adrenal medulla chromaffin cells secrete epinephrine and norepinephrine (NE) LM 50x (d) Subdivisions of adrenal gland 1 Dehydration, Na+ deficiency, or hemorrhage 2 Decrease in blood volume 14 4 3 Juxtaglomerular cells of kidneys Decrease in blood volume 15 5 Liver 6 10 7 Adrenal cortex Increased angiotensin I 16 9 12 Increased angiotensin II Increased aldosterone Increased blood volume Increased K+ in extracellular fluid 11 ACE Lungs (ACE = angiotensin converting enzyme) 13 Vasoconstriction of arterioles Increased renin Angiotensinogen 8 Blood pressure increases until it returns to normal In kidneys, increased Na+ and water reabsorption and increased secretion of K+ and H+ into urine Some stimulus disrupts homeostasis by Decreasing Glucocorticoid level in blood Receptors Neurosecretory cells in hypothalamus Input Increased CRH and decreased cortisol Control center Corticotrophs in anterior pituitary Output Increased ACTH Effectors Cells of zona fasciculata in adrenal cortex secrete glucocorticoids Increased glucocorticoid level in blood Return to homeostasis when response brings glucocorticoid level in blood back to normal Androgens (mainly dehydroepiandrosterone, or DHEA) from zona reticularis cells Adrenal cortex Epinephrine and norepinephrine from chromaffin cells Adrenal medulla Common hepatic artery Pancreas Kidney Abdominal aorta Celiac trunk Splenic artery Gastroduodenal artery Dorsal pancreatic artery Anterior pancreaticoduodenal artery Spleen (elevated) Duodenum of small intestine TAIL OF PANCREAS BODY OF PANCREAS Inferior pancreatic artery Superior mesenteric artery Inferior pancreaticoduodenal artery HEAD OF PANCREAS (a) Anterior view Blood capillary Exocrine acini Alpha cell (secretes glucagon) Beta cell (secretes insulin) Delta cell (secretes somatostatin) F cell (secretes pancreatic polypeptide) (b) Pancreatic islet and surrounding acini Exocrine acinus Pancreatic islet Beta cell Alpha cell LM 200x Pancreatic duct LM 40x (c) Pancreatic islet and surrounding acini Pancreas Duodenum (cut open) (d) Anterior view of pancreas dissected to reveal pancreatic duct 1 Low blood 5 High blood glucose (hyperglycemia) stimulates beta cells to secrete glucose(hypoglycemia) stimulates alpha cells to secrete GLUCAGON 2 Glucagon acts on INSULIN 6 hepatocytes (liver cells) to: • accelerate facilitated diffusion of glucose into cells • speed conversion of glucose into glycogen (glycogenesis) • increase uptake of amino acids and increase protein synthesis • speed synthesis of fatty acids (lipogenesis) • slow glycogenolysis • slow gluconeogenesis • convert glycogen into glucose (glycogenolysis) • form glucose from lactic acid and certain amino acids (gluconeogenesis) 3 Glucose released by hepatocytes raises blood glucose level to normal 4 If blood glucose continues to rise, hyperglycemia inhibits release of glucagon Insulin acts on various body cells to: 7 Blood glucose level falls 8 If blood glucose continues to fall, hypoglycemia inhibits release of insulin Glucagon from alpha cells of pancreatic islets Insulin from beta cells of pancreatic islets Alpha cell Beta cell Somatostatin from delta cells of pancreatic islets Pancreatic polypeptide from F cells of pancreatic islets Delta cell F cell Estrogens and progesterone Ovaries Testosterone Testes STRESSORS stimulate CRH GHRH TRH Nerve impulses Hypothalamus Sympathetic centers in spinal cord Anterior pituitary Key: CRH = Corticotropin-releasing hormone ACTH = Adrenocorticotropic hormone GHRH = Growth hormone–releasing hormone hGH = Human growth hormone TRH = Thyrotropin-releasing hormone TSH = Thyroid-stimulating hormone TSH hGH ACTH Sympathetic nerves ACTH Adrenal medulla Adrenal cortex hGH Liver TSH Thyroid gland Visceral effectors Cortisol Epinephrine and norepinephrine Supplement and prolong “fight-orflight” responses STRESS RESPONSES 1. Increased heart rate and force of beat 2. Constriction of blood vessels of most viscera and skin 3. Dilation of blood vessels of heart, lungs, brain, and skeletal muscles 4. Contraction of spleen 5. Conversion of glycogen into glucose in liver 6. Sweating 7. Dilation of airways 8. Decrease in digestive activities 9. Water retention and elevated blood pressure (a) Fight-or-flight responses IGFs STRESS RESPONSES Lipolysis Gluconeogenesis Protein catabolism Sensitized blood vessels Reduced inflammation Thyroid hormones (T3 and T4) STRESS RESPONSES STRESS RESPONSES Lipolysis Glycogenolysis Increased use of glucose to produce ATP (b) Resistance reaction Pharyngeal pouches Hypothalamus Neurohypophyseal bud 4 3 2 1 Hypophyseal (Rathke’s) pouch Stomodeum Esophagus Respiratory diverticulum Thyroid diverticulum (a) Location of neurohypophyseal bud, hypophyseal (Rathke’s) pouch, thyroid diverticulum, and pharyngeal pouches in 28-day embryo Neurohypophyseal bud Hypothalamus Infundibulum Infundibulum Pars intermedia Infundibulum Hypophyseal (Rathke’s) pouch Mouth cavity Mesenchyme Anterior pituitary Posterior pituitary (b) Development of pituitary gland between 5 and 16 weeks (a) A 22-year-old man with pituitary giantism shown beside his identical twin (b) Acromegaly (excess hGH during adulthood) (c) Goiter (enlargement of thyroid gland) (d) Exophthalmos (excess thyroid hormones, as in Graves’ disease) (e) Cushing’s syndrome (excess glucocorticoids)