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Chapter 16: The Endocrine System Arnold Adolph Berthold 1803 – 1861 Founder of Endocrinology Berthold’s Experiment in Roosters…. Castration Castration & Reimplantation of testis Castration & Transplantation of testis Berthold’s Conclusion... -A secretory, blood-borne product of the transplanted testes is responsible for the normal development of the birds in the second and third group Today, it is called TESTOSTERONE -’problem’: no one knows why Berthold did the experiment in the first place…. No clear rationale for it. Figure 16.1: Location of the major endocrine organs of the body, p. 605. Pineal gland Hypothalamus Pituitary gland Thyroid gland Parathyroid glands (on dorsal aspect of thyroid gland) Thymus gland Adrenal glands Pancreas Ovary (female) Testis (male) Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.3: PIP second-messenger mechanism of amino acid-based hormones, p. 608. Extracellular fluid Hormone DAG 1 4 2 Receptor Gq Catecholamines TRH ADH GnRH Oxytocin Cytoplasm Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn GTP GTP 3 GTP 5 Active protein kinase C PIP2 GDP Phospholipase C IP3 Inactive protein kinase C Triggers responses of target cell 5 Endoplasmic reticulum 6 Ca2+ Ca2+-calmodulin Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.4: Direct gene activation mechanism of steroid hormones, p. 609. Steroid hormone Cytoplasm Steroid hormone Receptorchaperonin complex Receptor-hormone complex Binding Transcription mRNA Molecular chaperones Hormone response elements Chromatin mRNA Nucleus New protein Ribosome Translation Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.5: Three types of endocrine gland stimuli, p. 612. 1 Capillary blood contains low concentration of Ca2+, which stimulates… Capillary (low Ca2+ in blood) Thyroid gland (posterior view) Parathyroid glands 1 Preganglionic SNS fiber stimulates adrenal medulla cells… CNS (spinal cord) Preganglionic SNS fiber 1 The hypothalamus secretes hormones that… Hypothalamus 2 …stimulate the anterior pituitary gland to secrete hormones that… Pituitary gland Medulla of adrenal gland Thyroid gland Parathyroid glands Adrenal cortex Gonad (Testis) PTH 2 …secretion of parathyroid hormone (PTH) by parathyroid glands Capillary 2 …to secrete catecholamines (a) Humoral Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn (b) Neural 3 …stimulate other endocrine glands to secrete hormones (c) Hormonal Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.6: Relationships of the pituitary gland and hypothalamus, p. 613. Hypothalamic neurons in the paraventricular nuclei Neurons in the ventral hypothalamus Hypothalamic neurons in the supraoptic nuclei Infundibulum (connecting stalk) Superior hypophyseal artery Hypothalamichypophyseal tract Hypophyseal portal system • Primary capillary plexus • Hypophyseal portal veins • Secondary capillary plexus Anterior lobe Neurohypophysis (storage area for hypothalamic hormones) Posterior lobe Secretory cells of adenohypophysis Venule TSH, FSH, LH, ACTH, GH, PRL Venule Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Inferior hypophyseal artery Oxytocin ADH Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.7: Metabolic actions of growth hormone (GH), p. 615. Inhibits GHRH release Stimulates GHIH release Feedback mechanism Inhibits GH synthesis and release Hypothalamus secretes growth hormone – releasing Anterior hormone (GHRH), and pituitary somatostatin (GHIH) Key: Growth hormone Increases, stimulates Direct effects Reduces, inhibits Initial stimulus Liver and other tissues Physiological response Result Insulin-like growth factors (IGFs) Anti-insulin actions Indirect growth-promoting actions Skeletal effects Extraskeletal effects Fat Carbohydrate metabolism Increased cartilage formation and skeletal growth Increased protein synthesis, and cell growth and proliferation Increased lipolysis Increased blood glucose and other anti-insulin effects Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.8: Gross and microscopic anatomy of the thyroid gland, p. 620. Colloid-filled Follicle cells follicles Hyoid bone Thyroid cartilage Epiglottis Internal carotid artery External carotid artery Superior thyroid artery Common carotid artery Inferior thyroid artery Isthmus of thyroid gland Trachea Left subclavian artery Left lateral lobe of thyroid gland Brachiocephalic artery Aorta Parafollicular cell (a) Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn (b) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.11: The parathyroid glands, p. 624. Pharynx (posterior aspect) Thyroid gland Capillary Parathyroid glands Chief cells Esophagus Trachea (a) Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Oxyphil cells (b) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.12: Effect of parathyroid hormone on bone, the intestine, and the kidneys, p. 625. Hypocalcemia (low blood calcium) stimulates parathyroid glands Key: = Ca2+ ions = PTH molecules Rising Ca2+ in blood inhibits PTH release PTH release from parathyroid glands PTH: Activates osteoclasts; calcium and phosphate ions released into blood Bone Intestine Increases calcium absorption from food Promotes activation Kidney of vitamin D Increases calcium reabsorption Bloodstream Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.13: Microscopic structure of the adrenal gland, p. 626. Capsule Zona glomerulosa Adrenal gland Zona fasciculata • Medulla • Cortex Zona reticularis Kidney Adrenal medulla (a) Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn (b) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.16: Stress and the adrenal gland, p. 631. Stress Short term More prolonged Hypothalamus Nerve impulses CRH (corticotropinreleasing hormone) Spinal cord Corticotroph cells of anterior pituitary Preganglionic sympathetic fibers To target in blood Adrenal cortex ACTH Adrenal medulla Short-term stress response 1. Increased heart rate 2. Increased blood pressure Catecholamines 3. Liver converts glycogen to glucose (epinephrine and releases glucose to blood and norepinephrine) 4. Dilation of bronchioles 5. Changes in blood flow patterns leading to decreased digestive system activity and reduced urine output 6. Increased metabolic rate Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Mineralocorticoids Glucocorticoids Long-term stress response 1. Retention of sodium and 1. Proteins and fats water by kidneys converted to glucose 2. Increased blood volume or broken down for and blood pressure energy 2. Increased blood glucose 3. Suppression of immune system Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.18: Regulation of blood glucose levels by insulin and glucagon, p. 633. Stimulates glucose uptake by cells Insulin Tissue cells Pancreas Stimulates glycogen formation Glucose Glycogen Blood glucose falls to normal range Liver Stimulus: Rising blood glucose level Homeostasis: Normal blood glucose level (about 90 mg/100 ml) Stimulus: Declining blood glucose level Blood glucose rises to normal range Pancreas Glycogen Glucose Stimulates glycogen breakdown Glucagon Liver Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings. Figure 16.1: Modified to emphasize the relationship between the adrenal glands and the testes and ovaries. Testes & Ovaries These gamete producing glands produce the lion’s share of sex hormone for each sex. Ovaries are in females and Testes are in males. There is, however, an important role for the adrenal glands… Adrenal glands Ovary (female) Testis (male) Human Anatomy and Physiology, 7e by Elaine Marieb & Katja Hoehn Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings.