CHAPTER © 2011 The McGraw-Hill Companies, Inc. All rights reserved. 30 The Endocrine System

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes 30.1Define the term endocrine glands. 30.2Describe the general functions of the endocrine system. 30.3Define the term hormone. 30.4Explain the difference in hormone control by positive and negative feedback loops.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes (cont.) 30.5Describe the locations of the hypothalamus, pituitary gland, pineal body, thyroid gland, parathyroid glands, adrenal glands, pancreas, thymus, and gonads. 30.6List the hormones released by the pituitary gland and give the functions of each. 30.7List the hormones released by the thyroid gland and parathyroid glands and give the functions of each.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes (cont.) 30.8List the hormones released by the adrenal glands and give the functions of each. 30.9List the names of the endocrine cells of the pancreas, the hormones released by them, and the function of each hormone List the hormones released by the pineal body, thymus, and gonads, and give the functions of each.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Learning Outcomes (cont.) 30.11Name the hormones produced by the kidneys and heart, listing which organ produces the hormone, and the hormone’s function Describe stressors and their effect on the body Describe the causes, signs and symptoms, and treatment of various endocrine disorders.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved target tissues Introduction The endocrine system includes the organs of the body that secrete hormones directly into body fluids such as blood –Regulates chemical reaction in cells and therefore control functions of the organs, tissues, and other cells Glands secrete hormones into bloodstream to

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Hormones Endocrine glands –Ductless –Release hormones Directly into target tissues Into bloodstream to be carried to target tissues Hormones – chemicals secreted by a cell that affect the functions of other cells

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Hormones (cont.) Many are derived from steroids that easily cross the cell membrane Examples of steroidal hormones –Estrogen –Progesterone –Testosterone –Cortisol Hormones

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Hormones (cont.) Nonsteroidal hormones –Made of amino acids or proteins and cannot cross the cell membrane easily –Bind to receptors on the surface of the cells –G-protein – activated by the hormone-receptor complex Activates enzymes inside cell Prostaglandins –Local, or tissue, hormones –Derived from lipid molecules –Do not travel in the bloodstream –Target tissues are located close by –Produced by organs such as Kidneys Heart Stomach Uterus Brain

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Feedback Loops Control hormone levels Negative feedback loop –Hormone release stops in response to decrease in stimulus Stimulus (eating) raises blood glucose levels Pancreas releases insulin in response to elevated blood glucose Blood glucose decreases as it is used by the body or stored in the liver Insulin release stops as blood glucose levels normalize

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Feedback Loops (cont.) Positive feedback loop –As long as stimulus is present, action of hormone continues Infant nursing at mother’s breast  stimulates hypothalamus  stimulates posterior pituitary Oxytocin released  stimulates milk production and ejection from mammary glands Milk release continues as long as infant continues to nurse

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Match the following: ___Chemicals that effect cell functionA.Nonsteroidal hormone ___Easily cross cell membranesB.Steroidal hormone ___Made of amino acidsC.G-protein ___Target nearby cellsD.Prostaglandins ___Activated by hormone-receptor E.Hormones complex ___Cannot cross cell membranes easily ___Estrogen and cortisol B A D C A B E ANSWER:

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Hypothalamus Hormones –Oxytocin –Antidiuretic hormone (ADH) Hormones transported to the posterior pituitary for storage Directs posterior pituitary to release hormones Glands

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Pituitary Gland Controlled by the hypothalamus Located at the base of the brain –Protected by a bony structure called the sella turcica –The optic chiasm is located just above the pituitary gland Carries visual information to the brain for interpretation Two lobes –Anterior lobe –Posterior lobe Glands Pituitary Gland

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Anterior Lobe Growth hormone Prolactin Adrenocorticotropic (ACTH) Thyroid-stimulating (TSH) Follicle-stimulating Luteinizing Stimulates milk production Stimulates the adrenal cortex to release its hormones Stimulates the thyroid gland to release its hormones Females: stimulates estrogen production and maturation of the ova Males: stimulates sperm production Females: stimulates ovulation and estrogen production Males: stimulates testosterone production Pituitary Gland (cont.) Stimulates increase in size of muscles and bones

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Posterior Lobe Antidiuretic hormone (ADH) Oxytocin Stimulates the kidneys to conserve water Females: causes contraction of the uterus and ejection of breast milk Males: stimulates contraction of the prostate and vas deferens during sexual arousal Pituitary Gland (cont.)

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Match the following: ___ Stored in posterior pituitaryA. Follicle-stimulating hormone ___ Milk productionB. Prolactin ___ Produced by hypothalamusC. Luteinizing hormone ___ Stimulates sperm production D. ADH ___ Maturation of ova E. Oxytocin ___ Stimulates ovulation ___ Conservation of water ___ Production of testosterone ___ Contraction of uterus E D B D, E C A A C ANSWER: Super!

© 2011 The McGraw-Hill Companies, Inc. All rights reserved T 3 T 4 Thyroid Gland  Located below the larynx  Divided into follicles that store some of the hormones Major hormones Stimulate protein synthesis and increase cellular energy production Lowers blood calcium levels by activating osteoblasts that build new bone tissue Glands

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Parathyroid Glands Four located on the posterior surface of the thyroid gland Secrete parathyroid hormone (PTH) –Agonist to calcitonin by raising blood calcium levels through activation of osteoclasts (dissolve bone) As bone dissolves, calcium levels in blood increase Glands

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge True or False: __ Thyroid hormones stimulate protein synthesis. __ The thyroid gland does not store hormones. __ PTH activates osteoblasts. __ Calcitonin increases cellular energy production. __ The four parathyroid glands are located on the thyroid gland. __ Calcitonin lowers blood calcium levels. F F F T T T ANSWER: PTH activates osteoclasts. Thyroid hormone increases cellular energy production. Thyroid follicles store some hormones.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Adrenal Glands Located on top of each kidney Divided into the adrenal medulla and adrenal cortex Adrenal medulla –Central portion –Hormones Epinephrine Norepinephrine Same effects as sympathetic nervous system Glands

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Adrenal Glands (cont.) Adrenal cortex –Outermost portion – Secretes many hormones, but main ones are Aldosterone –Stimulates body to retain sodium and water –Important in maintaining BP Cortisol –Released when stressed –Decreases protein synthesis, resulting in slowed tissue repair –Decreases inflammation

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Match the following: ____ Adrenal medullaA. Cortisol ____ Sodium retentionB. Epinephrine ____ Decreases inflammationC. Aldosterone ____ Sympathetic effectsD. Norepinephrine ____ Maintains blood pressure ____ Released during stress ____ Adrenal cortex A, C B, D A C A C ANSWER: Excellent!

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Pancreas Located behind the stomach Both exocrine gland and endocrine gland –Exocrine – secretes digestive enzymes into a duct leading to the small intestine –Endocrine – secretes hormones into bloodstream Glands

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Pancreas (cont.) Islets of Langerhans secrete hormones into bloodstream –Alpha cells secrete glucagon –Beta cells secrete insulin Blood glucose concentrations Protein synthesis Blood glucose concentrations Protein synthesis

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge What are the effects of insulin and glucagon? ANSWER: Insulin decreases blood glucose concentration and increases protein synthesis. Glucagon does just the opposite. It increases blood glucose and decreases protein synthesis. Yippee !

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Other Hormone-Producing Organs Pineal body –Small gland –Located between cerebral hemispheres –Melatonin Regulates circadian rhythms May play a role in onset of puberty Thymus gland –Located between lungs –Thymosin Promotes production of T lymphocytes Glands

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Other Hormone-Producing Organs (cont.) The gonads –Ovaries Estrogen Progesterone –Testes Testosterone Stomach –Gastrin Small intestine –Secretin –Cholecystokinin Heart –Atrial natriuretic peptide – regulates BP Kidneys –Erythropoietin – stimulates blood cell production Glands

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Back

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Match the following: ___ Between lungsA.Pineal body ___ MelatoninB.Heart ___ Estrogen/testosteroneC.Kidneys ___ GastrinD.Thymus gland ___ SecretinE.Small intestine ___ ErythropoietinF.Stomach ___ Atrial natriuretic peptideG.Gonads ___ Thymosin ___ Cholecystokinin C E F G A E D B D ANSWER:

© 2011 The McGraw-Hill Companies, Inc. All rights reserved The Stress Response Stressor –Any stimulus that produces stress –Types Physical factors Psychological factors Positive stimuli

© 2011 The McGraw-Hill Companies, Inc. All rights reserved The Stress Response (cont.) Physiologic response to stress caused by hormone release –General stress syndrome Increased heart rate, respiratory rate, and BP Increase in glucose and fatty acids in blood, which leads to weight loss Increase in cortisol if stress prolonged –Decreased body repair –Susceptibility to illness

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge Match the following: ___ Extreme heatA. Physical stress ___ Death of friendB. Psychological stress ___ Fractured legC. Positive stimulus ___ Wedding ___ Exam ___ Hearing an explosion nearby ___ “A” on an exam ___ Flu ___ Car stolen B B B A A C B C A ANSWER:

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Common Diseases and Disorders Disease/DisorderDescription AcromegalyToo much growth hormone produced in adults; enlargement of bones and thickened skin Addison’s diseaseAdrenal gland fails to produce enough corticosteroids CretinismExtreme form of hypothyroidism present prior to or soon after birth Cushing’s diseaseHypercortisolism; over-production of cortisol Diabetes insipidusKidneys fail to reabsorb water, resulting in excessive urination; hyposecretion of ADH

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Common Diseases and Disorders (cont.) Disease/DisorderDescription Diabetes mellitus Type I Type II Gestational Chronic disease characterized by elevated blood glucose levels Insulin-dependent diabetes mellitus; usually develops in childhood Noninsulin-dependent diabetes mellitus; primarily in adults but increased incidence in teens Occurs during pregnancy; usually temporary DwarfismToo little growth hormone (somatotropin) produced during childhood

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Common Diseases and Disorders (cont.) Disease/DisorderDescription GigantismToo much growth hormone produced during childhood GoiterEnlargement of thyroid gland, causing swelling in neck; deficiency of iodine in diet Graves’ diseaseHyperthyroidism; antibodies attach to thyroid gland, causing it to produce too much thyroid hormone MyxedemaThyroid gland produces inadequate amounts of thyroid hormone; common in females over 50

© 2011 The McGraw-Hill Companies, Inc. All rights reserved Apply Your Knowledge True or False: ___ Acromegaly develops as a result of too much growth hormone in a child. ___ In diabetes insipidus, the kidneys fail to reabsorb water. ___ Too little growth hormone in childhood results in dwarfism. ___ Myxedema is the result of hyperthyroidism. ___ Addison’s disease is the result of too little corticosteroid. ___ Cushing’s disease is the result of too little ACTH. ___ Cretinism is an extreme form of hyperthyroidism present at birth. F T T T F F ANSWER: F hypothyroidism too much ACTH hypothyroidism in an adult Correct !

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary 30.1Endocrine glands are ductless glands, releasing hormones directly into the bloodstream and tissues. 30.2The organs of the endocrine system produce hormones that regulate the chemical reactions within cells, controlling the functions of organs, tissues, and other cells. 30.3Hormones are chemicals released by cells that affect the functioning of other cells.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 30.4In a negative feedback loop, a stimulus causes a body reaction, which is detected by another area of the body, which stops the reaction. The rise in blood sugar causing the pancreas to release insulin to lower blood sugar is an example. In a positive feedback loop, a stimulus begins a process which will continue as long as the stimulus continues; as happens with a nursing infant, where the suckling releases milk from the mother’s breast until the suckling stops.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 30.5The hypothalamus, pituitary, and pineal glands are located within the brain. The thyroid and parathyroid glands are located in the neck. The thymus is found in the mediastinum. The adrenal glands are located above each kidney, and the pancreas is located behind the stomach. In females, the gonads (ovaries) are in the abdominal cavity and in males, the gonads (testes) are found within the scrotal sac.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 30.6The pituitary gland releases the following hormones: GH, MSH, ACTH, TSH, FSH, LH, PRL, ADH and OT. Each hormone’s specific function may be found in Table The thyroid gland releases calcitonin, T 3, and T 4 which are important in growth and protein synthesis. The parathyroid releases PTH which balances the action of calcitonin.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 30.8The adrenal medulla secretes epinephrine and norepinephrine, which work with the sympathetic nervous system. The adrenal cortex produces many hormones, but the two major ones are aldosterone for BP maintenance and cortisol, which decreases inflammation. 30.9The endocrine cells of the pancreas are known as the Islets of Langerhans. The two types of cells are Alpha cells, which release glucagon, and Beta cells, which release insulin.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 30.10The pineal body releases melatonin to regulate circadian rhythms, the thymus releases thymosin and thymopoietin to promote T cell production, ovaries release estrogen and progesterone (females), and the testes (males) release testosterone The kidneys produce erythropoietin, affecting the bone marrow, and the heart produces atrial natriuretic peptide, affecting BP.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved In Summary (cont.) 30.12Stressors are defined as stimuli that produce a stress response, a physiologic response to the stimulus that changes the body’s functioning in some way The diseases and disorders of the endocrine system are as varied as the organs and hormone dysfunctions that cause them. An overview of these conditions is in Table 30-2, and more detail on the most common of these conditions is found in the Pathophysiology section at the end of this chapter.

© 2011 The McGraw-Hill Companies, Inc. All rights reserved End of Chapter 30 Its not stress that kills us, it is our reaction to it. ~ Hans Selye