Chapter 13: Endocrine System Lecture Outline PDF

Because learning changes everything. ® Chapter 13 Lecture Outline See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the...

Because learning changes everything. ® Chapter 13 Lecture Outline See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 13.1 General Characteristics of the Endocrine System Endocrine system Along with nervous system, regulates functions of body to maintain homeostasis, and coordinates communication Unique system, since organs are not anatomically connected Major endocrine glands: Pituitary gland Thyroid gland Parathyroid glands Adrenal glands Pancreas Pineal gland Thymus Ovaries and Testes (reproductive glands) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 2 Figure 13.1 Locations of Major Endocrine Glands Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 3 Characteristics of the Endocrine System Endocrine glands: Cells, tissues, and organs that make up the endocrine system Ductless; secrete hormones directly into the body fluids “Endocrine” means “internal secretion” Hormones act only on target cells that contain receptors for them Exocrine glands: Glands that secrete into ducts or tubes that lead to a body surface Secrete externally Deliver their products directly to a specific site Other cells secrete chemical messengers internally, called “local hormones (not actually hormones): Paracrine secretions affect nearby cells Autocrine secretions affect only the cells that secrete them Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 4 Figure 13.2 Types of Glands Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 5 Comparison Between Nervous and Endocrine Systems Both the nervous and endocrine systems function in communication Both systems communicate via chemicals that bind to receptor molecules Nervous system releases neurotransmitters into synapses Endocrine system secretes hormones into bloodstream Nervous system responds faster than endocrine system Endocrine system’s effects can last longer than those of nervous system Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 6 Table 13.1 A Comparison Between Nervous and Endocrine Systems Cells Neurons Glandular epithelium The first Chemical column is Neurotransmitter signal unlabeled, the secondHormone column shows nervous system, and the third column shows endocrine system.of action Specificity Receptors on Receptors on target postsynaptic cell cell Speed of onset 1 second Seconds to hours Duration of action Very brief unless May be brief or may neuronal activity last for days even if continues secretion ceases Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 7 Figure 13.3 Chemical Communication In Nervous and Endocrine Systems Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 8 Table 13.2 Hormone Names and Abbreviations 1 Source Name Abbreviation Synonym Hypothalamus Corticotropin-releasing hormone CRH Gonadotropin-releasing hormone GnRH Luteinizing hormone-releasing hormone (LHRH) Somatostatin SS Growth hormone release-inhibiting hormone (GHRIH) The first column shows source, the Growth hormone-releasing hormone GHRH second column shows Prolactin release-inhibiting hormone PIH Dopamine name, the third column shows abbreviation, and the fourth column shows synonym. Prolactin-releasing factor* PRF* Thyrotropin-releasing hormone TRH Anterior pituitary gland Adrenocorticotropic hormone ACTH Corticotropin Follicle-stimulating hormone FSH Follitropin Growth hormone GH Somatotropin (STH) Luteinizing hormone LH Lutropin, interstitial cell-stimulating hormone (ICSH) Prolactin PRL Thyroid-stimulating hormone TSH Thyrotropin *”Factor” is used because specific prolactin-releasing hormones have not yet been identified Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 9 Table 13.2 Hormone Names and Abbreviations 2 Source Name Abbreviation Synonym Posterior pituitary gland Antidiuretic hormone ADH Vasopressin Oxytocin OT The first columnCalcitonin Thyroid gland shows source, the second column shows name, the third column shows Thyroxineabbreviation, and T the fourth column shows Tetraiodothyronine4 synonym. Triiodothyronine T 3 Parathyroid gland Parathyroid hormone PTH Parathormone Adrenal medulla Epinephrine EPI Adrenalin Norepinephrine NE Noradrenalin Adrenal cortex Aldosterone Cortisol Hydrocortisone Pancreas Glucagon Insulin Somatostatin SS Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 10 13.2 Hormone Action Hormones: Are released into extracellular fluid Then diffuse into blood Method of transport through blood depends on whether hormone is lipid-soluble of water-soluble Very powerful substances in low concentrations Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 11 Chemistry of Hormones Hormones are organic compounds; 2 general types: Steroid or steroid-like hormones: Steroids: lipids containing complex rings of carbon and hydrogen atoms All steroid hormones are produced from cholesterol Examples: Sex hormones (testosterone, estrogens), and adrenal cortex hormones (cortisol, aldosterone) Nonsteroid hormones: Amines: Derived from tyrosine (epinephrine, norepinephrine, thyroxine) Proteins: Composed of long chains of amino acids (growth hormone) Peptides: Short chains of amino acids (ADH, oxytocin) Glycoproteins: Carbohydrates joined to proteins (TSH) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 12 Table 13.3 Types of Hormones Type of Compound Formed from Examples Amines Amino acids Norepinephrine, The first column shows type of compound, the epinephrine second column shows Peptides Aminoformed acids from, and theOT, ADH, third TRH, SS, column shows examples. GnRH Proteins Amino acids PTH, GH, PR Glycoproteins Protein and FSH, LH, TSH carbohydrate Steroids Cholesterol Estrogens, testosterone, aldosterone, cortisol Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 13 Figure 13.4 Structural Formulas of Hormones Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 14 Actions of Hormones Hormone Actions: Exert effects by altering metabolic processes: May alter enzyme activity May change rate of membrane transport of a substance Deliver messages by binding to their receptors on/in target cell Can cause changes in target cells even in extremely low concentrations Number of receptors determines strength of response, and can be changed to alter the response: Upregulation: Increase in number of receptors on target cell, in response to a decrease in hormone level Downregulation: Decrease in number of receptors on target cell, due to an increase in hormone level Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 15 Steroid and Thyroid Hormones Steroid and Thyroid Hormones: Have poor water-solubility Transported through blood bound to plasma proteins Steroid hormones can diffuse through lipid bilayer of cell membranes Thyroid hormones are thought to enter cell by specific transport methods Both types bind to receptors inside cell, usually in nucleus Cause transcription of particular genes in DNA Protein synthesis leads to the action of the hormone Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 16 Table 13.4 Sequence of Steroid Hormone Action 1. Endocrine gland secretes steroid hormone. 2. Blood carries hormone molecules (often weakly bound to transport protein) throughout theThe body.rows show the sequence of steroid hormone action. 3. Unbound steroid hormone diffuses through target cell membrane and enters cytoplasm or nucleus. 4. Hormone combines with a receptor molecule in the cytoplasm or nucleus 5. Steroid hormone-receptor complex binds to DNA in the nucleus and promotes transcription of messenger RNA. 6. Messenger RNA enters the cytoplasm and directs protein synthesis. 7. Newly synthesized proteins produce the steroid hormone’s specific effects. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 17 Figure 13.5 Steroid Hormone Action Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 18 Nonsteroid Hormones Nonsteroid Hormones: Cannot penetrate the lipid bilayer of cell membranes Bind to receptors on the target cell membranes Hormone is considered a first messenger Chemical that induces changes leading to hormone’s effect is considered a second messenger Many hormones use cyclic adenosine monophosphate (cAMP) as a second messenger The entire process of chemical communication, from outside cells to inside, is called signal transduction Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 19 Table 13.5 Sequence of Actions of Nonsteroid Hormone Using cAMP 1. Endocrine gland secretes nonsteroid hormone. 2. Blood The carries rows hormone show the molecules sequence throughout the body. of actions of Nonsteroid 3. Hormone using c A M P. Hormone combines with receptor site on membrane of its target cell, activating G protein. 4. Adenylate cyclase molecules are activated in target cell’s membrane. 5. Adenylate cyclase converts ATP into cyclic AMP. 6. Cyclic AMP activates protein kinases. 7. Protein kinases activate protein substrates in the cell that change metabolic processes. 8. Cellular changes produce the hormone’s effects. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 20 Figure 13.7 Nonsteroid Hormone Action Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 21 Clinical Application 13.1 Abusing Hormones to Improve Athletic Performance Steroids: Used to increase muscular strength Can have many harmful effects, such as decreasing natural testosterone production, stunting growth, breast development in males, male sexual characteristics in females, damage to kidneys, liver or heart, increase in LDL cholesterol, psychiatric problems Growth Hormone (Human Growth Hormone, or HGH): Used to enlarge muscles Used instead of, or along with, steroids Erythropoietin: Used to increase the number of red blood cells and oxygen delivery to muscles Used to treat certain forms of anemia, but using it to improve athletic performance is not advised because it can lead to heart attack and death Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 22 Actions of Prostaglandins Prostaglandins: Paracrine substances Are very potent in small amounts, like hormones Are not stored in cells, but synthesized just before release Rapidly inactivated after use Regulate cellular responses to hormones Can activate or inhibit adenylate cyclase, to control cAMP production, and changing a cell’s response to hormone Have a wide variety of effects, such as contracting or relaxing smooth muscle, stimulating or inhibiting secretion, regulating blood pressure, pressure, controlling movement of H2O and Na+ in the kidneys, promoting inflammation Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 23 13.3 Control of Hormonal Secretions Hormone secretion and effects: Secretion is precisely regulated Secretion is primarily controlled by negative feedback mechanisms Effects can be short-lived (a few minutes) or may last for days. Some are excreted in the urine after exerting their effects Can be broken down by enzymes, mainly from the liver, to stop their effects Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 24 Control Sources Negative feedback: A control mechanism in which rising level of a hormone leads to a decrease in hormone secretion As hormone is used up, inhibition stops, and secretion begins again Main methods of control of hormone secretion 3 methods of negative feedback control of hormone secretion: Hypothalamus controls release of anterior pituitary hormones; then pituitary hormones secrete hormones that control activity of other glands. (Tropic hormones: Hormones that act on other glands) Nervous system control: Nervous system directly stimulates some glands to secrete their hormones (via nerve impulses) Changes in composition of internal environment: Changing levels of a specific substance in the blood (an ion, glucose, etc.) stimulates or inhibits secretion of certain hormones Positive feedback: Control mechanism in which rising level of a hormone leads to an increase in secretion; used in small number of cases of hormone control, mainly in reproductive system Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 25 Figure 13.8 Endocrine System Control Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 26 Figure 13.9 Control by Negative Feedback Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 27 Figure 13.10 Negative Feedback Control Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 28 13.4 Pituitary Gland Pituitary Gland: Lies at the base of the brain, in the sella turcica of sphenoid bone Controlled by brain, and considered part of nervous system Attached to hypothalamus by pituitary stalk (infundibulum) Consists of 2 distinct portions: Anterior lobe (adenohypophysis) Posterior lobe (neurohypophysis) Secretion from 2 lobes is controlled by different methods by the hypothalamus Small intermediate lobe (pars intermedia) develops in fetus; produces melanocyte-stimulating hormone (MSH), which starts melanin production Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 29 Figure 13.11 Pituitary Gland Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 30 Hypothalamic Control of Pituitary Gland Anterior Lobe Regulation: Hypothalamic releasing hormones (or release-inhibiting hormones) are transported to anterior lobe through the Hypophyseal Portal Veins (example of a portal system) Stimulate cells of anterior lobe to release hormones Each releasing hormone acts on specific group of cells in anterior pituitary, and can stimulate or inhibit pituitary secretion Posterior Lobe Regulation: Nerve impulses from the hypothalamus travel to posterior lobe through the infundibulum Stimulate nerve endings in posterior lobe to release hormones Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 31 Figure 13.12 Hypothalamic Control of Pituitary Gland Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 32 Hypothalamic Control of Peripheral Endocrine Glands The hypothalamus, which is an endocrine gland, controls hormone secretion from peripheral endocrine glands via 3-step pathways: Releasing (or release-inhibiting) hormone from hypothalamus acts on specific hormone-secreting cells in the anterior pituitary gland Anterior pituitary hormone acts on cells in a peripheral endocrine gland, to stimulate its secretion Peripheral endocrine gland secretes its hormone, which exerts effects on target cells Usually, there are multiple negative feedback controls involved in these pathways: Final hormone in pathway inhibits secretion of both the releasing hormone and anterior pituitary hormone Anterior pituitary hormone inhibits secretion of releasing hormone Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 33 Figure 13.13 Hypothalamic Control of Peripheral Endocrine Glands Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 34 Anterior Pituitary Hormones Anterior lobe of pituitary gland consists of glandular epithelial tissue Anterior pituitary hormones are produced in the anterior lobe, by 1 of 5 types of secretory cells Each anterior lobe hormone is released in response to a releasing hormone from the hypothalamus; some are inhibited by release-inhibiting hormones from the hypothalamus Major anterior pituitary hormones: Growth hormone (GH) Prolactin (PRL) Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 35 Releasing Hormones of the Hypothalamus Secretion of each anterior pituitary hormone is regulated by a Releasing Hormone, a Release-inhibiting Hormone, or both from the hypothalamus: Growth hormone (GH): Released by Growth hormone-releasing hormone (GHRH) Inhibited by Growth hormone-inhibiting hormone (GHIH, or somatostatin, SS) Prolactin (PRL): Inhibited by Prolactin-inhibiting hormone (PIH) Perhaps released by Prolactin-releasing factor (PRF) Thyroid-stimulating hormone (TSH or Thyrotropin): Released by Thyrotropin-releasing hormone (TRH) Adrenocorticotropic hormone (ACTH or Corticotropin): Released by Corticotropin-releasing hormone (CRH) Follicle-stimulating hormone (FSH) and Luteinizing hormone (LH): Both released by Gonadotropin-releasing hormone (GnRH) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 36 Figure 13.15 Hormones of the Hypothalamus, Anterior Pituitary, and Target Organs Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 37 Functions of Anterior Pituitary Hormones Growth Hormone (somatotropin): Stimulates cells to enlarge and divide rapidly, increases amino acid uptake and protein synthesis, decreases rate of carbohydrate usage, increases rate of fat usage Prolactin: Promotes milk production in females, uncertain function in males Thyroid-stimulating Hormone (TSH): Stimulates secretion of thyroid hormones (T3 and T4) from thyroid gland Adrenocorticotropic Hormone (ACTH): Stimulates secretion of cortisol and other glucocorticoids from adrenal cortex Follicle-stimulating Hormone (FSH): Causes growth and development of ovarian follicles in females, sperm production in males Luteinizing Hormone (LH): Causes ovulation in females, sex hormone production in both genders Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 38 Pathway for Thyroid Hormone Secretion Pathway for Thyroid Hormone secretion: TRH is secreted by hypothalamus TRH causes anterior pituitary to secrete TSH TSH travels to thyroid gland, and causes it to secrete Thyroid Hormones Thyroid hormones exert effects on target cells Thyroid hormones also exert negative feedback on secretion of TRH and TSH TSH secretion is controlled by 2 methods in this pathway: TSH secretion is controlled to some extent by the level of TRH TSH secretion is also controlled by negative feedback by thyroid hormones, the final hormones in the pathway Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 39 Figure 13.16 TRH-TSH-Thyroid Hormone Pathway Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 40 Clinical Application 13.2 Growth Hormone Ups and Downs Hypopituitary Dwarfism: Caused by deficiency of human growth hormone (HGH) during childhood Short stature, but body proportions and mental development are normal HGH treatment must start before bones completely ossify Gigantism: Caused by oversecretion of GH during childhood Height may exceed 8 feet, may have other metabolic problems Often caused by pituitary tumor Acromegaly: Caused by oversecretion of GH during adulthood, after epiphyseal ossification No increase in height, but bones thicken Enlargement of tongue, nose, hands, feet, jaw, heart, thyroid gland Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 41 Posterior Pituitary Hormones Posterior lobe of pituitary gland consists of nerve fibers from hypothalamus and neuroglia, unlike glandular epithelium of anterior lobe 2 hormones are produced in hypothalamus, and stored and released by posterior pituitary gland These hormones are transported to the posterior pituitary gland via the pituitary stalk (infundibulum) Posterior pituitary hormones: Antidiuretic hormone (ADH, vasopressin): Decreases urine production by reducing volume of H2O the kidneys excrete Causes vasoconstriction to increase blood pressure Oxytocin: Causes muscle contraction in uterine wall during childbirth Causes milk ejection during lactation Has no proven function in males, but may help with sperm movement or sexual response Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 42 Table 13.6 Hormones of the Pituitary Gland Anterior Lobe Action Source of Control Growth hormone (GH) Stimulates increase in size and rate of Secretion inhibited by somatostatin (SS) division of body cells; enhances and stimulated by growth hormone- movement of amino acids through releasing hormone (GHRH) from the The first part of the table shows the following columns: the membranes; promotes growth of long bones hypothalamus first column shows Sustains Prolactin (PRL) Anterior lobe, the second column milk production after birth; Secretion inhibited by prolactin inhibiting shows Action, the third column shows Source hormone amplifies the effect of LH in males of control. (PIH) from the hypothalamus The second part ofControls Thyroid-stimulating hormone (TSH) the table thyroid gland shows the following secretion of hormones from the Thyrotropin-releasing hormone (TRH) from the hypothalamus Adrenocorticotropic hormone (ACTH) Controls secretion of certain hormones Corticotropin-releasing hormone (CRH) from the adrenal cortex from the hypothalamus Follicle-stimulating hormone (FSH) Promotes development of egg- Gonadotropin-releasing hormone containing follicles in ovaries; stimulates (GnRH) from the hypothalamus follicular cells to secrete estrogen; in males, stimulates production of sperm cells Luteinizing hormone (LH) Promotes secretion of male and female Gonadotropin-releasing hormone sex hormones; releases egg cell in (GnRH) from the hypothalamus females Posterior Lobe Action Source of Control Antidiuretic hormone (ADH) Causes kidneys to reduce water Hypothalamus in response to changes columns: the firstexcretion; column mayshows Posterior help maintain blood lobe, in bodythe fluid concentration and blood pressure volume second column shows Action, the third column shows Oxytocin (OT) Contracts smooth muscle in the uterine Hypothalamus in response to stretching Source of control.wall; forces liquid from the milk glands uterine and vaginal walls and stimulation into the milk ducts, ejects milk of breasts Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 43 13.5 Thyroid Gland Thyroid gland: Consists of two lateral lobes, connected by an isthmus Lies just below the larynx, anterior and lateral to the trachea Has special ability to remove iodine from blood Produces 3 hormones: T4 (thyroxine), produced by follicular cells T3 (triiodothyronine), produced by follicular cells Calcitonin, produced by extrafollicular cells Thyroid is composed of round secretory units called follicles Each follicle is surrounded by a single layer of follicular cells Viscous colloid fills follicle cavities Extrafollicular (C) cells lie outside follicles Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 44 Figure 13.19 Thyroid Gland Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 45 Figure 13.20 Structure of the Thyroid Gland © Dr. Fred Hossler Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 46 Figure 13.21 and Table 13.7 Hormones of the Thyroid Gland Hormone Action Source of Control Thyroxine (T4 ) Increases rate of energy TSH from the release from anterior pituitary carbohydrates; increases gland rate of protein synthesis; accelerates growth; necessary for normal The first column shows nervous systemhormone, maturation the second column shows Triiodothyronine (T ) action, Same andbutthe as above, 3 muchthirdSame column as above shows Source of control. more potent than thyroxine Calcitonin Lowers blood calcium and Elevated blood phosphate ion calcium ion concentrations by concentration, inhibiting release of digestive hormones calcium and phosphate ions from bones and by increasing the rate at which calcium and phosphate ions are deposited in bones; increases excretion of calcium by the kidneys Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 47 Table 13.8 Disorders of the Thyroid Gland Condition Mechanism/Symptoms Hyperthyroid The first column shows Hyperthyroidism Condition, High andsensitivity metabolic rate, the second to heat,column shows restlessness, mechanism slash symptoms. hyperactivity, weight loss, protruding eyes, goiter Graves disease Autoantibodies (against self) bind TSH receptors on thyroid cell membranes, mimicking action of TSH, overstimulating gland (hyperthyroidism); exopthalmia (protrusion of the eyes) and goiter Hypothyroid Hashimoto disease Autoantibodies (against self) destroy thyroid cells, resulting in hypothyroidism Hypothyroidism (infantile) Stunted growth, abnormal bone formation, intellectual disability, sluggishness Hypothyroidism (adult) Low metabolic rate, sensitivity to cold, sluggishness, poor appetite, swollen tissues, mental dullness Simple goiter Deficiency of thyroid hormones due to iodine deficiency; because no thyroid hormones inhibit pituitary release of TSH, thyroid is overstimulated and enlarges but functions below normal (hypothyroidism) Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 48 Figures 13.22, 13,23 and 13,24 Infantile Hypothyroidism, Graves’ Disease, and Simple Goiter Left: ©Medical-on-Line/Alamy; Middle: ©imagingbody.com; Right: © Lester V. Vergman/Corbis Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 49 13.6 Parathyroid Glands Parathyroid Glands: Located on posterior surface of the thyroid gland. Usually 4 parathyroid glands Secrete 1 hormone, Parathyroid hormone (PTH, also called Parathormone). PTH regulates Ca+2 and PO4−2 concentrations in the blood Actions of PTH: Increases blood level of calcium, and decreases phosphate Acts on bones, kidneys, intestines to exert effects: Acts on bones to stimulate bone resorption Indirectly stimulates calcium absorption by stimulating a step in Vitamin D metabolism Acts on kidney to cause final step in production of Active Vitamin D (also called Calcitriol, Dihydroxycholecalciferol) Acts on kidney to conserve calcium and excrete phosphate in urine Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 50 Figure 13.25 Parathyroid Glands Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 51 Figure 13.27 PTH and Calcium Absorption Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 52 Figure 13.28 Parathyroid Hormone (PTH) Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 53 Table 13.9 Disorders of the Parathyroid Gland Condition Symptoms/Mechanism Cause Treatment Hyperparathyroidism Fatigue, muscular weakness, Tumor Remove tumor, The first column shows painful Condition, joints, altered mentalthe second columncorrect shows bone functions, depression, weight deformities symptoms slashloss, mechanism, bone weakening.cause, and treatment. Increased PTH secretion overstimulates osteoclasts. Hypoparathyroidism Muscle cramps and seizures. Inadvertent Calcium salt Decreased PTH secretion surgical injections, massive reduces osteoclast activity, removal; injury doses of vitamin D diminishing blood calcium ion concentration. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 54 13.7 Adrenal Glands Adrenal glands: Also called suprarenal glands Closely associated with the kidneys; sit like a cap on each kidney Numerous hormones are secreted by the adrenal glands Adrenal hormones play roles in maintaining blood sodium levels and responding to stress, and include certain sex hormones Adrenal Gland contains 2 portions: cortex and medulla Different hormones are secreted from cortex and medulla: Adrenal cortex: Outer portion of gland Secretes steroid hormones: Aldosterone, Cortisol, Sex hormones Adrenal medulla: Central portion of gland Secretes amine hormones: 80% Epinephrine, 20% Norepinephrine Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 55 Hormones of the Adrenal Cortex Adrenal Cortex has 3 zones, each producing different types of hormones: Zona glomerulosa: Outer zone Produces aldosterone and other mineralocorticoids Zona fasciculata: Middle zone Produces cortisol and other glucocorticoids Zona reticularis: Inner zone Produces male sex hormones called androgens Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 56 Figures 13.29 and 13.30 Structure of the Adrenal Glands Ed Reschke/Getty Images Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 57 Table 13.10 Comparative Effects of Epinephrine and Norepinephrine Structure or Function Affected Epinephrine Norepinephrine Heart The first column showsHeart structure or function affected, rate increases Heart the second rate increases Force of contraction increases Force of contraction increases column shows epinephrine, Blood vessels and the third column shows Vasodilation, especially important in Vasoconstriction in skin and viscera norepinephrine. skeletal muscle at onset of fight or shifts blood flow to other areas, such flight as exercising skeletal muscle Systemic blood pressure Some increase due to increased Some increase due to increased cardiac output cardiac output and vasoconstriction (offset in some areas, such as exercising skeletal muscle, by local vasodilation due to other factors) Airways Dilation Some dilation Reticular formation of brainstem Activated Little effect Liver Promotes breakdown of glycogen to Little effect on blood glucose level glucose, increasing blood sugar level Metabolic rate Increases Increases Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 58 Table 13.11 Hormones of the Adrenal Cortex Hormone Action Factors Regulating Secretion Aldosterone Helps regulate the concentration Plasma potassium and sodium The first column shows hormone, of extracellular thebysecondion electrolytes column shows action, concentrations and renin- and the thirdconserving sodiumfactors column shows ions andregulatingangiotensin secretion.system excreting potassium ions Cortisol Decreases protein synthesis, CRH from the hypothalamus increases fatty acid release, and and adrenocorticotropic stimulates glucose synthesis from hormone (ACTH) from the noncarbohydrates anterior pituitary gland Adrenal Supplement sex hormones from Adrenocorticotropic hormone androgens the gonads; may be converted (ACTH) from the anterior into estrogens pituitary plus unknown factors Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 59 Aldosterone and the Renin-Angiotensin System Aldosterone: Promotes excretion of K+ ions by kidney Promotes conservation of Na+ by kidney H2O is retained along with Na+ by osmosis Renin-Angiotensin System: System that helps maintain normal blood pressure Angiotensin II, the product of this system increases blood pressure, and promotes secretion of aldosterone Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 60 Figure 13.33 Aldosterone and the Renin-Angiotensin System Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 61 Figure 13.35 Regulation of Cortisol Secretion Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 62 Clinical Application 13.3 Disorders of the Adrenal Cortex Addison Disease: Due to insufficient hormone secretion from adrenal cortex Results in electrolyte and glucose imbalances, dehydration, low blood pressure, fatigue, nausea, increased skin pigmentation Can be fatal, due to severe electrolyte imbalance Cushing Syndrome: Due to hypersecretion of cortisol, because of adrenal tumor, or excess secretion of ACTH by anterior pituitary Results in muscle wasting, loss of bone, elevated blood glucose, Na+ retention, H2O retention by osmosis, increased blood pressure, puffy skin, abnormal deposition of adipose tissue in face and back Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 63 13.8 Pancreas Pancreas: Elongated, flattened organ, posterior to stomach Pancreatic duct transports digestive juice to duodenum Contains 2 major types of secretory tissue Is both an endocrine and exocrine gland: Endocrine function: Secretes hormones into body fluids Exocrine function: Secretes digestive juices through Pancreatic Duct 3 hormones are secreted from the endocrine cells (Pancreatic islets or Islets of Langerhans): Glucagon: Secreted by alpha cells; increases blood glucose Insulin: Secreted by beta cells; decreases blood glucose Somatostatin: Secreted by delta cells; inhibits secretion of insulin and glucagon Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 64 Figures 13.36 and 13.37 Structure of the Pancreas Victor P. Eroschenko Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 65 Table 13.12 Hormones of the Pancreatic Islets Hormone Action Source of Control Glucagon Stimulates the liver to break down glycogen and Blood glucose concentration The firstconvert column noncarbohydrates shows hormone, breakdown of fats into glucose; stimulates the second column shows action, and the third column shows Source of control. Insulin Promotes formation of glycogen from glucose, inhibits Blood glucose concentration conversion of noncarbohydrates into glucose, and enhances movement of glucose through adipose and muscle cell membranes, decreasing blood glucose concentration; promotes transport of amino acids into cells; enhances synthesis of proteins and fats Somatostatin Helps regulate carbohydrates Not determined Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 66 Figure 13.38 Regulation of Blood Glucose Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 67 Clinical Application 13.4 (1) Diabetes Mellitus Metabolic disease resulting from lack of insulin or inability of cells to recognize insulin Elevated blood glucose can damage eyes, heart, kidney, nerves Results in disturbances in carbohydrate, protein, and fat metabolism Insulin normally promotes glucose uptake by adipose and muscle cells In diabetes mellitus, carbohydrates cannot enter cells in normal quantities Results in hyperglycemia, or high blood glucose Cells turn to other sources of energy, which promotes tissue wasting Weight declines, hunger increases, fatigue increases, wounds do not heal well, growth stops in children Glucose spills into urine (glycosuria), and H2O follows by osmosis, leading to dehydration and thirst Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 68 Clinical Application 13.4 (2) Diabetes Mellitus Type 1 Diabetes Mellitus: Also called juvenile or insulin-dependent; usually begins before age of 20 Autoimmune disease; immune system destroys beta cells of pancreas Results in a lack of insulin production 5 to 10% of cases are Type 1 Type 2 Diabetes Mellitus: Also called maturity-onset or non-insulin-dependent 90 to 95% of cases are Type 2 Insulin is produced, but body cells are unable to recognize it Milder than Type 1 Complications include coronary artery disease, nerve or retinal damage Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 69 From Science to Technology 13.1 Treating Diabetes Treating Type 1 Diabetes Mellitus: Requires administration of insulin Insulin can be obtained from pigs and cattle Human insulin can be synthesized using recombinant DNA technology; insulin is produced by genetically altered bacteria People receive insulin through injection, an insulin pump, or in aerosol form Transdermal delivery system (skin patch) is being developed Pancreatic islet transplantation is being used in some countries Treating Type 2 Diabetes Mellitus: Low carbohydrate, high protein diet Regular exercise Medications that increase glucose production Gastric bypass surgery Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 70 13.9 Pineal, Thymus, and Other Glands Pineal Gland: Found in brain, between cerebral hemispheres Secretes melatonin, which regulates circadian rhythms (day/night cycles) Thymus Gland: Found in mediastinum, between lungs Secretes thymosins, which promote development of T-lymphocytes Important role in immunity Other Glands: Reproductive Organs: Ovaries produce estrogens and progesterone, testes produce testosterone, and placenta produces estrogens, progesterone, and a gonadotropin Digestive glands: Produce hormones to regulate digestion Heart: Produces natriuretic peptides, to stimulate Na+ secretion in urine Kidney: Produces erythropoietin, to stimulate red blood cell formation Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 71 13.10 Stress and Its Effects Survival depends on maintaining homeostasis Factors that change the internal or external environment are potentially life-threatening Certain potentially dangerous factors can trigger a loss of homeostasis When sensory receptors detect changes, they send nerve impulses to the hypothalamus Hypothalamus activates sympathetic nervous system and increases secretion of adrenal hormones Factor capable of initiating this response is a stressor Stress is the condition produced in response to stressors Types of Stress: Psychological stress: Danger, personal loss, anger, fear, guilt Physical stress: Temperature extremes, infection, injury, O2 deficiency Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 72 Responses to Stress 1 Hypothalamus controls response to stress Response is called General Adaptation Syndrome (GAS) 2 stages of General Stress Syndrome: Alarm Stage: Fight or flight response; immediate, does not last long Sympathetic impulses increase blood glucose and fatty acids, heart and breathing rate, and blood pressure, dilate air passages, shunt blood to skeletal muscles, increases epinephrine secretion Epinephrine intensifies and prolongs these responses Resistance Stage: Slower, longer-lasting The CRH-ACTH-Cortisol pathway increases cortisol secretion Increased cortisol spares glucose for brain Cortisol, Glucagon, and GH mobilize energy sources for other tissues and organs ADH and Renin cause water retention Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 73 Responses to Stress 2 Exhaustion Stage: Begins after months of being in Resistance Stage Wasting due to depletion of nutrients in the body Electrolyte imbalance Suppression of immune system Effects are due to long-term oversecretion of cortisol Can result in death Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 74 Figure 13.39 General Adaptation Syndrome Access the text alternative for slide images. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 75 Table 13.13 Major Events in the General Stress Syndrome 1. In response to stress, impulses are conducted to the hypothalamus. 2. Sympathetic impulses originating from the hypothalamus increase blood glucose concentration, blood glycerol concentration, blood fatty acid concentration, heart rate, and blood pressure. They dilate air passages, shunt blood The rows show the major events in the general stress into skeletal muscles, and increase secretion of epinephrine from the adrenal medulla. 3. syndrome. Epinephrine intensifies and prolongs sympathetic actions. 4. The hypothalamus secretes CRH, which stimulates secretion of ACTH by the anterior pituitary gland. 5. ACTH stimulates release of cortisol by the adrenal cortex 6. Cortisol increases the concentration of blood amino acids, releases fatty acids, and stimulates formation of glucose from noncarbohydrate sources. 7. Secretion of glucagon from the pancreas and growth hormone from the anterior pituitary increase. 8. Glucagon and growth hormone aid mobilization of energy sources and stimulate uptake of amino acids by cells. 9. Secretion of ADH from the posterior pituitary increases. 10. ADH promotes the retention of water by the kidneys, which increases blood volume. 11. Renin increases blood levels of angiotensin II, which acts as a vasoconstrictor and also stimulates the adrenal cortex to secrete aldosterone. 12. Aldosterone stimulates sodium retention by the kidneys. 13. Long-term mobilization of nutrients depletes fat stores and leads to protein breakdown and eventual wasting. 14. Persistent sodium retention in response to aldosterone can cause potassium depletion and acid-base imbalance. Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 76 13.11 Life-Span Changes Endocrine glands decrease in size Muscular and skeletal strength decrease as GH levels decline ADH levels increase due to slower elimination by liver and kidneys Calcitonin levels decrease, increasing risk of osteoporosis PTH level changes contribute to risk of osteoporosis, especially in females Insulin resistance may develop Changes in melatonin secretion affect the body clock Thymosin production declines, increasing risk of infections Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC. 77  End of Main Content Because learning changes everything. ® www.mheducation.com Copyright 2022 © McGraw Hill LLC. All rights reserved. No reproduction or distribution without the prior written consent of McGraw Hill LLC.