Endocrine System Chapter 12 PDF

Endocrine System Chapter 12  Learning Objectives Lesson 12.1: Hormones (1 of 2) 1. Distinguish between endocrine and exocrine glands. 2. Define the term hormone. 3. Identify the principal functions of each major endocrine hormone and descr...

Endocrine System Chapter 12  Learning Objectives Lesson 12.1: Hormones (1 of 2) 1. Distinguish between endocrine and exocrine glands. 2. Define the term hormone. 3. Identify the principal functions of each major endocrine hormone and describe the conditions that may result from hyposecretion or hypersecretion. 4. Describe the mechanisms of steroid and nonsteroid hormone action.  Learning Objectives Lesson 12.1: Hormones (2 of 2) 5. Explain how negative and positive feedback mechanisms regulate the secretion of endocrine hormones. 6. Explain the primary mechanisms of endocrine conditions. 7. Define and explain the importance of prostaglandins (PGs).  Endocrine System Overview  Exocrine glands  Not part of endocrine system  Secrete their products into ducts that empty onto a surface or into a cavity  Endocrine glands  Ductless  Secrete hormones Chemical substances with regulatory effect on activity of target cells or organs Location of Endocrine Glands Mechanisms of Hormone Action  Endocrine glands secrete chemicals (hormones) into the blood  Hormones perform general functions of communication and control, but a slower, longer-lasting type of control than that provided by nerve impulses  Cells acted on by hormones are called target cells and are found within target organs  Nonsteroid and Steroid Hormones  Nonsteroid hormones (first messengers) bind to receptors on the target cell membrane, triggering second messengers to affect the cell’s activities  Steroid hormones bind to receptors within the target cell nucleus and influence cell activity by acting on DNA Mechanism of Protein Hormone Action Mechanism of Steroid Hormone Action Regulation of Hormone Secretion  Hormone secretion is controlled by homeostatic feedback  Negative feedback  Mechanisms that reverse the direction of a change in a physiological system  Positive feedback (uncommon)  Mechanisms that amplify physiological changes Negative Feedback  Mechanisms of Endocrine Disease  Hypersecretion: Secretion of excess hormone  Hyposecretion: Insufficient hormone secretion  Polyendocrine disorders: Hypersecretion or hyposecretion of more than one hormone  Target cell insensitivity produces results similar to hyposecretion  Endocrinologists have developed many different strategies for treatment (e.g., surgery and hormone therapy)  Prostaglandins  Prostaglandins (PGs) are powerful substances found in a wide variety of body tissues  PGs are often produced in a tissue and diffuse only a short distance to act on cells in that tissue  Several classes of PGs include prostaglandin A (PGA), prostaglandin E (PGE), and prostaglandin F (PGF)  PGs influence many body functions, including respiration, blood pressure, gastrointestinal secretions, and  Learning Objectives Lesson 12.2: The Endocrine Glands 6. Identify and locate the primary endocrine glands, list the major hormones produced by each gland, and identify disorders of the endocrine system.  Pituitary Gland  Anterior pituitary gland (adenohypophysis)  Adeno = gland  Posterior pituitary gland (neurohypophysis)  Neuro = nervous  Anterior Pituitary Gland  Anterior pituitary gland (adenohypophysis)  Names of major hormones Thyroid-stimulating hormone (TSH) Adrenocorticotropic hormone (ACTH) Follicle-stimulating hormone (FSH) Luteinizing hormone (LH) Growth hormone (GH) Prolactin (lactogenic hormone)  Functions of Major Hormones (1 of 3)  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)  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  Functions of Major Hormones (2 of 3)  LH: Acts with FSH to stimulate estrogen secretion and follicle growth to maturity; causes ovulation; causes luteinization of the ruptured follicle and stimulates progesterone secretion by corpus luteum  Functions of Major Hormones (3 of 3)  GH: Stimulates growth by accelerating protein anabolism; also accelerates fat catabolism and slows glucose catabolism; by slowing glucose catabolism, tends to increase blood glucose to higher than normal level (hyperglycemia)  Hypersecretion in childhood results in gigantism and during adulthood results in acromegaly  Hyposecretion in childhood results in pituitary dwarfism  Prolactin (PRL) or lactogenic hormone—stimulates breast development during pregnancy and secretion of milk after the delivery of the baby  Growth Hormone Abnormalities Courtesy Robert F Gagel, MD, and Ian McCutcheon, MD, University of Texas M.D. Anderson From Forbes CD and Jackson WF: Color atlas and text of clinical Cancer Center, Houston, Texas. In Black JM, Hawks JH: Medical-surgical nursing: clinical medicine, ed 3, Edinburgh, 2003, Mosby. management for positive outcomes, ed 8, St Louis, 2009, Mosby.  Posterior Pituitary Gland  Names of hormones  Antidiuretic hormone (ADH) Hyposecretion causes diabetes insipidus, characterized by excessive volume of urine  Oxytocin (OT)  Functions of Hormones  ADH: Accelerates water reabsorption from urine in the kidney tubules into the blood, thereby decreasing urine secretion  OT: Stimulates the pregnant uterus to contract; may initiate labor; causes glandular cells of the breast to release milk into ducts Pituitary Hormones  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)  Thyroid Gland  Names of hormones  Thyroid hormones: Thyroxine (T4) and triiodothyronine (T3)  Calcitonin (CT)  Functions of hormones  Thyroid hormones: Accelerate catabolism (increase the body’s metabolic rate)  Calcitonin: Decreases the blood calcium concentration by inhibiting breakdown of bone, which would release calcium into the blood Thyroid and Parathyroid Glands  Hyperthyroidism  Hypersecretion of thyroid hormones: Increases metabolic rate  Characterized by restlessness and exophthalmos (protruding eyes)  Graves disease From Seidel NM, Ball JW, Dains JE, Benedict GW: Mosby’s guide to physical examination, ed 4, St. Louis, 1999. is an inherited form of  Hypothyroidism  Hyposecretion of thyroid hormones  May result from different conditions  Goiter: Painless enlargement of thyroid caused by dietary deficiency of iodine  Hyposecretion during early development may result in cretinism (retardation) and during adulthood in myxedema (characterized by edema and sluggishness)  Goiter and Myxedema From Swartz MH: Textbook of physical examination, ed 6, From Forbes CD and Jackson WF: Color atlas and text of clinical Philadelphia, 2010, Saunders. medicine, ed 3, Edinburgh, 2003, Mosby.  Parathyroid Glands  Name of hormone  Parathyroid hormone (PTH)  Function of hormone  Increases blood calcium concentration by increasing the breakdown of bone with the release of calcium into the blood Regulation of Blood Calcium Levels Adrenal Glands: Adrenal Cortex (1 of 3)  Names of hormones (corticoids)  Glucocorticoids (GCs): Chiefly cortisol (hydrocortisone)  Mineralocorticoids (MCs): Chiefly aldosterone  Sex hormones: Small amounts of male hormones (androgens) secreted by adrenal cortex of both sexes Adrenal Glands: Adrenal Cortex (2 of 3)  Three cell layers (zones)  Outer layer secretes mineralocorticoids  Middle layer secretes glucocorticoids  Inner layer secretes sex hormones  Mineralocorticoids  Increase blood sodium and decrease body potassium concentrations by accelerating kidney tubule reabsorption of sodium and excretion of potassium Adrenal Glands: Adrenal Cortex (3 of 3)  Functions of Glucocorticoids (1 of 2)  Help maintain normal blood glucose concentration by increasing gluconeogenesis  Play an essential part in maintaining normal blood pressure  Functions of Glucocorticoids (2 of 2)  Act with epinephrine and norepinephrine to produce an anti- inflammatory effect  Produce anti-immunity, antiallergy effect  Secretion of glucocorticoid quickly increases when the body is thrown into a condition of stress  High blood concentration of glucocorticoids brings about many other stress responses Glucocorticoid Stress Responses  Adrenal Medulla  Names of hormones  Epinephrine (Epi), or adrenaline  Norepinephrine (NR)  Function of hormones  Help the body resist stress by intensifying and prolonging the effects of sympathetic stimulation  Adrenal Conditions  Hypersecretion of glucocorticoids  Causes Cushing syndrome  Hypersecretion of adrenal androgens  May result from a virilizing tumor  May cause masculinization of affected women  Hyposecretion of cortical hormones may result in Addison disease Cushing Syndrome Courtesy Gower Medical Publishers.  Pancreatic Islets  Names of hormones  Glucagon: Secreted by alpha cells  Insulin: Secreted by beta cells  Function of hormones  Glucagon increases the blood glucose level by accelerating glycogenolysis in liver (conversion of glycogen to glucose) Pancreas  Function of Hormones  Insulin decreases the blood glucose by accelerating the movement of glucose out of the blood into cells, which increases glucose metabolism by cells  Diabetes Mellitus (1 of 2)  Type 1 results from hyposecretion of insulin  Type 2 results from target cell insensitivity to insulin  Glucose cannot enter cells and thus blood glucose levels rise, producing glycosuria (glucose in the urine) Diabetes Mellitus (2 of 2)  Female Sex Glands  The ovaries contain two structures that secrete hormones  Ovarian follicles  Corpus luteum  Effects of estrogen (feminizing hormone)  Development and maturation of breasts and external genitals  Development of adult female body contours  Initiation of menstrual cycle  Male Sex Glands  The interstitial cells of testes secrete the male hormone testosterone  Effects of testosterone (masculinizing hormone)  Maturation of external genitals  Beard growth  Changes in voice at puberty  Development of muscular and body contours typical of the male  Thymus  Name of hormone  Thymosin  Function of hormone  Plays an important role in the development and function of the body’s immune system  Placenta  Names of hormones  Chorionic gonadotropins  Estrogens  Progesterone  Function of hormones  Maintain the corpus luteum during pregnancy  Pineal Gland (1 of 2)  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 third eye because its influence on secretory activity is related to the amount of light entering the eyes  Pineal Gland (2 of 2)  Secretes melatonin, which:  Inhibits ovarian activity  Regulates the body’s internal clock  Abnormal secretion of (or sensitivity to) melatonin may produce seasonal affective disorder (SAD)  Other Endocrine Structures  Many organs (e.g., the stomach, intestines, and kidney) produce endocrine hormones  Ghrelin is secreted by epithelial cells lining stomach; boosts appetite and slows 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 we feel Questions?