Endocrine System Chapter 11 PDF

Endocrine System Chapter 11 Copyright © 2016 by Elsevier Inc. All rights reserved. 1  Learning Objectives Lesson 11.1: Endocrine System 1. Distinguish between endocrine and exocrine glands and define t...

Endocrine System Chapter 11 Copyright © 2016 by Elsevier Inc. All rights reserved. 1  Learning Objectives Lesson 11.1: Endocrine System 1. Distinguish between endocrine and exocrine glands and define the terms hormone, hypersecretion, and hyposecretion. 2. Identify and locate the primary endocrine glands and list the major hormones produced by each gland. 3. Describe the mechanisms of steroid and nonsteroid hormone action. 4. Explain how negative and positive feedback mechanisms regulate the secretion of endocrine hormones. Copyright © 2016 by Elsevier Inc. All rights reserved. 2  Learning Objectives Lesson 11.1: Endocrine System (Cont.) 5. Define and explain the importance of prostaglandins (PGs). 6. Identify the principal functions of each major endocrine gland and the hormones that each releases. 7. Describe the conditions that may result from hyposecretion or hypersecretion of endocrine hormones, including gigantism, diabetes insipidus, goiter, cretinism, diabetes mellitus, and glycosuria. Copyright © 2016 by Elsevier Inc. All rights reserved. 3  Endocrine and Exocrine Glands  All organs of the endocrine system are glands, but not all glands are organs of the endocrine system  Two types of glands in the body  Exocrine glands  Endocrine glands Only endocrine glands belong to the endocrine system Secrete chemicals known as hormones into intercellular spaces Each hormone molecule then binds to a cell that has specific receptors for that hormone, triggering a reaction in the cell (target cell) Copyright © 2016 by Elsevier Inc. All rights reserved. 4  Mechanisms of Hormone Action  Endocrine glands secrete chemicals (hormones) into the blood (Figure 11-1)  Hypersecretion is too much hormone and hyposecretion is too little hormone  Hormones perform general functions of communication and control but a slower, longer-lasting type of control than that provided by nerve impulses in CNS  Two major classes of hormones  Nonsteroid ( Proteins)  Steroid Copyright © 2016 by Elsevier Inc. All rights reserved. 5 Location of the Endocrine Glands Copyright © 2016 by Elsevier Inc. All rights reserved. 6 Mechanisms of Hormone Action (Cont.)  Nonsteroid hormones (first messengers)  Are proteins that bind to receptors on the target cell membrane, triggering second messengers to affect the cell’s activities (Figure 11-2)  Steroid hormones  Primary effects produced by binding to receptors within the target cell nucleus and influence cell activity by acting on DNA: A slower process than nonsteroid action (Figure 11-3)  Secondary effects may occur when steroid hormones bind to membrane receptors to rapidly trigger functional changes in the target cell Copyright © 2016 by Elsevier Inc. All rights reserved. 7 Mechanism of Nonsteroid Hormone Action Copyright © 2016 by Elsevier Inc. All rights reserved. 8 Mechanism of Steroid Hormone Action Copyright © 2016 by Elsevier Inc. All rights reserved. 9  Regulation of Hormone Secretion  Hormone secretion is controlled by homeostatic feedback  Endocrine system exhibit different levels of regulation (pituitary, hypothalamus)  Negative feedback  Mechanisms that reverse the direction of a change in a physiological system (Figure 11-4)  Positive feedback  Uncommon mechanisms that amplify physiological changes rather than reverse them  Secretion of Oxytocin hormone during labor Copyright © 2016 by Elsevier Inc. All rights reserved. 10 Negative Feedback Copyright © 2016 by Elsevier Inc. All rights reserved. 11  Prostaglandins  Prostaglandins (PGs) are powerful substances found in a wide variety of body tissues  Often produced in a tissue (tissue hormones) and diffuse only a short distance to act on cells in that tissue (paracrine agents)  Several classes of PGs include prostaglandin A (PGA), prostaglandin E (PGE), and prostaglandin F (PGF)  Influence many body functions, including respiration, blood pressure, gastrointestinal secretions, Inflammation and reproduction Copyright © 2016 by Elsevier Inc. All rights reserved. 12  Pituitary Gland  Structure of the pituitary gland (Hypophyseal gland)  Two glands Adenohypophysis: Anterior pituitary gland Neurohypophysis: Posterior pituitary gland Sella turcica Pituitary connecting stalk to hypothalamus Copyright © 2016 by Elsevier Inc. All rights reserved. 13  Pituitary Gland (Cont.)  Anterior pituitary gland  Names of major hormones Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Growth hormone (GH) Prolactin (PRL); lactogenic hormone Copyright © 2016 by Elsevier Inc. All rights reserved. 14 Pituitary Hormones Copyright © 2016 by Elsevier Inc. All rights reserved. 15  Pituitary Gland (Cont.)  Anterior pituitary gland: Functions of major hormones  TSH Stimulates growth of the thyroid gland; also stimulates it to secrete thyroid hormone  ACTH Stimulates growth of the adrenal cortex and stimulates it to secrete glucocorticoids (mainly cortisol)(hydrocortisone)  FSH Initiates growth of ovarian follicles each month in the ovary and stimulates one or more follicles to develop to the stage of maturity and ovulation Stimulates estrogen secretion by developing follicles Stimulates sperm production in the male (seminiferous tubules) Copyright © 2016 by Elsevier Inc. All rights reserved. 16  Pituitary Gland (Cont.)  Anterior pituitary gland: Functions of major hormones  LH Acts with FSH to stimulate estrogen secretion and follicle growth to maturity Causes ovulation (ovulating hormone) Causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum Causes interstitial cells in the testes to secrete testosterone in the male Copyright © 2016 by Elsevier Inc. All rights reserved. 17  Pituitary Gland (Cont.)  Anterior pituitary gland: Functions of major hormones  GH Stimulates growth by accelerating protein anabolism Accelerates fat catabolism and slows glucose catabolism By slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia) Increase GH leads to gigantism or acromegaly, hypo secretion leads to dwarfism.  PRL Stimulates breast development during pregnancy and secretion of milk after the delivery of the baby (lactogenic H.) Copyright © 2016 by Elsevier Inc. All rights reserved. 18  Pituitary Gland (Cont.)  Posterior pituitary gland hormones  Antidiuretic hormone (ADH) Accelerates water reabsorption from urine in the kidney tubules into the blood, thereby decreasing urine secretion Hyposecretion of ADH results in diabetes insipidus  Oxytocin (OT) Stimulates the pregnant uterus to contract May initiate labor Causes glandular cells of the breast to release milk into ducts Enhances social bonding (Mother-infant) Copyright © 2016 by Elsevier Inc. All rights reserved. 19  Hypothalamus  Actual production of ADH and oxytocin occurs in the hypothalamus  After production in the hypothalamus, hormones pass along axons into the pituitary gland  The secretion and release of posterior pituitary hormones is controlled by nervous stimulation  The hypothalamus controls many body functions related to homeostasis (temperature, appetite, and thirst)  It produces releasing and inhibiting hormones for the hormones produced by the anterior pituitary gland Copyright © 2016 by Elsevier Inc. All rights reserved. 20  Thyroid Gland  Thyroid hormones  Thyroxine (T4)  Triiodothyronine (T3)  Accelerate catabolism (increase the body’s metabolic rate)  Thyroid follicles, and colloid  Hypothyroid, cretinism, goiter and hyperthyroid  Calcitonin (CT)  Decreases the blood calcium concentration by inhibiting breakdown of bone, which would release calcium into the blood Copyright © 2016 by Elsevier Inc. All rights reserved. 21 Thyroid and Parathyroid Glands Copyright © 2016 by Elsevier Inc. All rights reserved. 22  Parathyroid Glands  Parathyroid glands are small lumps of glandular epithelium  Parathyroid hormone (PTH)  Increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood Copyright © 2016 by Elsevier Inc. All rights reserved. 23 Regulation of Blood Calcium Levels Copyright © 2016 by Elsevier Inc. All rights reserved. 24  Adrenal Glands  Adrenal cortex  Zones of the adrenal cortex Corticoids: Hormones secreted by three cell layers (zones) Outer zone secretes mineralocorticoids (MCs): Chiefly aldosterone Middle zone secretes glucocorticoids (GCs): Chiefly cortisol (hydrocortisone) Innermost/deepest zone secretes sex hormones: Small amounts of male hormones (androgens) secreted by adrenal cortex of both sexes Copyright © 2016 by Elsevier Inc. All rights reserved. 25 The Adrenal Gland Copyright © 2016 by Elsevier Inc. All rights reserved. 26  Adrenal Glands (Cont.)  Adrenal cortex  Cushing syndrome and Addison disease  Aldosterone: The chief mineralocorticoid  Mineralocorticoids (MCs) MCs increase blood sodium and decrease body potassium concentrations by accelerating kidney tubule reabsorption of sodium and excretion of potassium. Copyright © 2016 by Elsevier Inc. All rights reserved. 27  Adrenal Glands (Cont.)  Adrenal cortex  Cortisol: The chief glucocorticoid (GC)  Functions of GCs Help maintain normal blood glucose concentration by increasing gluconeogenesis: The formation of “new” glucose from amino acids produced by the breakdown of proteins, mainly those in muscle tissue cells; also the conversion to glucose of fatty acids produced by the breakdown of fats stored in adipose tissue cells Play an essential part in maintaining normal blood pressure: Make it possible for epinephrine and norepinephrine to maintain a normal degree of vasoconstriction, a condition necessary for maintaining normal blood pressure Copyright © 2016 by Elsevier Inc. All rights reserved. 28  Adrenal Glands (Cont.)  Adrenal cortex  Functions of GCs Act with epinephrine and norepinephrine to produce an anti-inflammatory effect, to bring about normal recovery from inflammations of various kinds Produce anti-immunity, anti-allergy effect; bring about a decrease in the number of lymphocytes and plasma cells and therefore a decrease in the amount of antibodies formed Secretion of glucocorticoid quickly increases when the body is thrown into a condition of stress; high blood concentration of glucocorticoids, in turn, brings about many other stress responses (Figure 11-10) Copyright © 2016 by Elsevier Inc. All rights reserved. 29 Stress Responses Copyright © 2016 by Elsevier Inc. All rights reserved. 30  Adrenal Glands (Cont.)  Adrenal medulla  Secretes hormones Epinephrine (Epi), or adrenaline Norepinephrine (NR)  Functions of hormones Help the body resist stress by intensifying and prolonging the effects of sympathetic stimulation Increased epinephrine secretion is the first endocrine response to stress Copyright © 2016 by Elsevier Inc. All rights reserved. 31  Pancreatic Islets of Langerhans  Glucagon: Secreted by alpha cells  Increases the blood glucose level by accelerating liver glycogenolysis (conversion of glycogen to glucose)  Insulin: Secreted by beta cells  Decreases the blood glucose by accelerating the movement of glucose out of the blood into cells, which increases glucose metabolism by cells Copyright © 2016 by Elsevier Inc. All rights reserved. 32  Pancreas Copyright © 2016 by Elsevier Inc. All rights reserved. 33  Female Sex Glands  The ovaries contain two structures that secrete hormones  Ovarian follicles (see Chapter 21)  Corpus luteum (see Chapter 21)  Effects of estrogen (feminizing hormone)  Development and maturation of breasts and external genitals  Development of adult female body contours  Initiation of menstrual cycle Copyright © 2016 by Elsevier Inc. All rights reserved. 34  Male Sex Glands  The interstitial cells of testes secrete the male hormone testosterone (see Chapter 21)  Effects of testosterone (masculinizing hormone)  Maturation of external genitals  Beard growth  Voice changes at puberty  Development of musculature and body contours typical of the male Copyright © 2016 by Elsevier Inc. All rights reserved. 35  Thymus  Name of hormone  Thymosin  Function of hormone  Plays an important role in the development and function of the body’s immune system Copyright © 2016 by Elsevier Inc. All rights reserved. 36  Placenta  Produces hormones  Chorionic gonadotropins  Estrogen  Progesterone  Function of hormones  Maintain the corpus luteum during pregnancy Copyright © 2016 by Elsevier Inc. All rights reserved. 37  Pineal Gland  A small gland near the roof of the third ventricle of the brain  Glandular tissue predominates in children and young adults  Becomes fibrous and calcified with age  Called the third eye because its influence on secretory activity is related to the amount of light entering the eyes  Secretes melatonin, which:  Inhibits ovarian activity  Melatonin levels increase at night and decrease during day  Regulates the body’s internal clock Copyright © 2016 by Elsevier Inc. All rights reserved. 38  Endocrine Functions Throughout the Body  Many organs (e.g., the stomach, intestines, and kidney) produce endocrine hormones  Stomach lining produces ghrelin, which affects appetite and metabolism  The atrial wall of the heart secretes atrial natriuretic hormone (ANH), which stimulates sodium loss from the kidneys  Fat-storing cells secrete leptin, which controls how full or hungry one feels Copyright © 2016 by Elsevier Inc. All rights reserved. 39  Endocrine Hormone Conditions  Gigantism  Hypersecretion of growth hormone during the early years of life  Diabetes insipidus  Hyposecretion of ADH  Goiter  Low dietary take of iodine Copyright © 2016 by Elsevier Inc. All rights reserved. 40 Endocrine Hormone Conditions (Cont.)  Cretinism  Hyposecretion of thyroid hormones during the formative years  Diabetes mellitus  Type 1 Pancreatic islets secrete too little insulin  Type 2 Decrease of insulin and an abnormality of the insulin receptors  Glycosuria  Excess glucose is filtered out of the blood and lost in the urine Copyright © 2016 by Elsevier Inc. All rights reserved. 41  Questions? Copyright © 2016 by Elsevier Inc. All rights reserved. 42