Chapter 16: The Endocrine System - Human Anatomy and Physiology PDF

Human Anatomy and Physiology Third Edition Chapter 16 The Endocrine System PowerPoint® Lectures Created by Karen L. Keller Frostburg State University...

Human Anatomy and Physiology Third Edition Chapter 16 The Endocrine System PowerPoint® Lectures Created by Karen L. Keller Frostburg State University Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine System (1 of 4) The two major regulatory systems of the body are the nervous system and the Endocrine System Organs of the endocrine system work by synthesizing and secreting chemical messengers called Hormones into the blood Hormones interact with cells known as Target Cells Tissues in which a hormone’s target cells reside are referred to as Target Tissues Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine System (2 of 4) Figure 16.1 Overview of hormone secretion and distribution by the blood Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine System (3 of 4) Overview of Functions: 1) Metabolism and Tissue Maturation—Regulates the rate of metabolism 2) Ion Regulation—Regulates blood pH, sodium, potassium, calcium, and other ion levels in various tissues 3) Water Balance—Regulates the solute concentration of blood 4) Immune System Regulation Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine System (3 of 4) Overview of Functions, cont.: 5) Heart Rate and Blood Pressure Regulation—Controls directly and through blood volume 6) Blood Glucose and Other Nutrients—Regulates blood and tissue levels 7) Reproductive Functions 8) Uterine Contractions and Milk Release Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Paracrine and Autocrine Signals (1 of 2) Hormones that are secreted into the blood to affect distance targets are known as Classic Endocrine Signals Hormones can be secreted into the interstitial fluid and affect local cells without entering the blood Paracrine—Signals consist of a chemical secreted by cells into the extracellular fluid (EC F) to influence nearby cells Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Paracrine and Autocrine Signals (2 of 2) Figure 16.2 Three basic signaling pathways Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine Organs (1 of 4) Endocrine Glands—Organs of the endocrine system Hormones can require seconds to several hours or days to elicit their effects, but the effects are generally longer- lasting than those of the nervous system Consist of ductless glandular epithelial cells that secrete hormones into the interstitial fluid Exocrine glands secrete their products into ducts that lead to body surfaces or cavities Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine Organs (2 of 4) There are seven Primary Organs of the endocrine system: Anterior Pituitary Gland, in the sphenoid bone of the skull Thyroid Gland, in the anterior neck Parathyroid Glands, on the posterior thyroid Adrenal Cortices, on the superior surface of the kidneys Endocrine Pancreas, in the left side of the abdominopelvic cavity mostly posterior to the stomach Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine Organs (3 of 4) Secondary Endocrine Glands—Organs that produce hormones, but belong to other systems Testes and Ovaries may be considered secondary endocrine glands Includes the Heart, Kidneys, Small Intestine, and Adipose Tissue Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Overview of the Endocrine Organs (4 of 4) Figure 16.3 Overview of the endocrine organs Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Paraneoplastic Syndrome Many types of cancer cells can produce hormones Signs and symptoms that accompany hormone secretion from cancer cells are collectively called Paraneoplastic Syndrome Most common types of cancer cells that cause this syndrome are cells of lung and gastrointestinal cancers Common effects include imbalances in fluid, calcium ion, and sodium ion homeostasis Symptoms of paraneoplastic syndrome often precede other symptoms of the cancer, and investigating them may lead to an earlier diagnosis Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Hormones (1 of 6) Classes of Hormones Amino Acid-Based Hormones—Derived from an amino acid; Most are hydrophilic Peptide/Protein Hormones—Consist of many amino acids linked by peptide bonds; Generally hydrophilic Bind to plasma membrane receptors (water soluble and unbound) Steroid Hormones—Cholesterol derivatives; Hydrophobic or Lipid-Soluble because they can mix with fats and be stored in adipose tissue Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Hormones (2 of 6) Target Cells and Receptors Hormone receptors may be embedded in the plasma membrane; Bind hydrophilic and hydrophobic hormones Hormone receptors may be in the cytosol or nucleus; Bind only hydrophobic hormones Hydrophilic hormones are usually administered via injection Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Hormones (3 of 6) Figure 16.4 A hydrophilic amino acid–based hormone mechanism of action via second-messenger system Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Hormones (4 of 6) Figure 16.5 Mechanism of action of hydrophobic hormones (steroids and thyroid hormones) via binding an intracellular receptor Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Hormones (5 of 6) Target Cells and Receptors (continued) Number of receptors in the target cells varies with the body’s needs; Allows cells to have tight control over their interaction with hormones Upregulation—When the level of a hormone in the blood declines, target cells make more receptors for the hormone and increase the cells’ sensitivity to the hormone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Hormones (6 of 6) Hormone Interactions Complementary Actions—Hormones affect different target cells to accomplish a common goal; For example, hormones of the adrenal gland and pancreas work together to maintain homeostasis during exercise Synergists—Hormones act on the same target cell to exert the same effect Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Regulation of Hormone Secretion (1 of 4) Hormone secretion can be initiated by different stimuli: Hormonal Stimuli—Some endocrine cells increase or decrease their secretion in response to other hormones; Hypothalamus regulates secretion of the anterior pituitary by secreting Releasing and Inhibiting hormones Humoral Stimuli—Many endocrine cells respond to the concentration of an ion or compound in the blood or EC F; Pancreas releases insulin in response to elevated glucose levels in the blood Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Regulation of Hormone Secretion (2 of 4) Figure 16.6 Types of stimuli for hormone secretion Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Regulation of Hormone Secretion (3 of 4) Negative Feedback Loop Regulation: 1) Stimulus: A regulated physiological variable deviates from its normal range 2) Receptor: Receptors detect the deviation in the variable 3) Control Center: Endocrine Cell increases or decreases its secretion of a particular hormone 4) Effector/Response: Target cells moves conditions toward the normal range 5) Return to Normal Range: Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.1 Regulation of Hormone Secretion (4 of 4) Figure 16.7 Maintaining homeostasis: regulation of hormone secretion by negative feedback loops Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Structure of the Hypothalamus and Pituitary Gland (1 of 2) Hypothalamus is a region of the brain; Connects to the Pituitary Gland (Hypophysis) by the Infundibulum Anterior Pituitary Gland (Adenohypophysis)—True gland composed of hormone-secreting cells Hypothalamic-Hypophyseal Portal System—Some capillaries merge in the hypothalamus and form Portal Veins that travel through the infundibulum to another group of capillaries in the anterior pituitary Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Structure of the Hypothalamus and Pituitary Gland (2 of 2) Figure 16.8 Structure of the hypothalamus and pituitary gland Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Hormones of the Hypothalamus and Posterior Pituitary (1 of 2) Antidiuretic Hormone (ADH) (Vasopressin) Increases water retention and helps to control water balance Directly affects kidney tubules Oxytocin Stimulates uterine contractions and milk ejection “milk letdown” from mammary glands if stimulated by suckling Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Hormones of the Hypothalamus and Posterior Pituitary (2 of 2) Figure 16.9a Functional relationships between the hypothalamus and pituitary gland Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Functional Relationship of the Hypothalamus and Anterior Pituitary (1 of 7) Hypothalamus produces Tropic Hormones that either stimulate (Releasing), or inhibit (Inhibiting) the release of other hormones from the anterior pituitary For example, gonadotropin-releasing hormone (GnRH) stimulates gonadotropin release from the pituitary Hormones of the hypothalamus, anterior pituitary, and their target tissues are maintained by negative feedback loops with Tiers of Control Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Functional Relationship of the Hypothalamus and Anterior Pituitary (2 of 7) Figure 16.9b Functional relationships between the hypothalamus and pituitary gland Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Functional Relationship of the Hypothalamus and Anterior Pituitary (3 of 7) Figure 16.10 Multi-tiered negative feedback control of hormones of the hypothalamus, anterior pituitary gland, and target organs Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Functional Relationship of the Hypothalamus and Anterior Pituitary (4 of 7) Thyroid-Stimulating Hormone (TSH) Stimulates thyroid hormone secretion Adrenocorticotropic Hormone (ACTH) Stimulates glucocorticoid hormone secretion Prolactin (PRL) Stimulates growth of mammary gland tissue and initiates milk production after childbirth Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Functional Relationship of the Hypothalamus and Anterior Pituitary (5 of 7) Luteinizing Hormone (L H) Male—Stimulates production of testosterone Female—Stimulates production of estrogens and progesterone; Triggers ovulation Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Functional Relationship of the Hypothalamus and Anterior Pituitary (6 of 7) Figure 16.11 Hormones of the hypothalamic-anterior pituitary system and the target organs of anterior pituitary hormones Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Functional Relationship of the Hypothalamus and Anterior Pituitary (7 of 7) Lipotropins Increase fat breakdown Beta (β) Endorphins Analgesic in brain; Inhibition of gonadotropin-releasing hormone secretion Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Big Picture Animation: Response by the Hypothalamus Use the link below to view AD A compliant video: Big Picture Animation: Response by the Hypothalamus [ https://mediaplayer.pearsoncmg.com/assets/_video.tru e/secs-ap-endocrine-02-response-hypothalamus ] Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.2 Pseudoscience Exposed: Human Growth Hormone and the “Fountain of Youth” Synthetic human Growth Hormone (hG H) is a popular supplement with body builders, those seeking to lose weight, and individuals trying to fight the signs of aging G H does promote fat breakdown and protein synthesis and adult patients with G H deficiency who are treated with hG H do lose fat and gain muscle However, elevated blood glucose levels and growth of the tongue, bones of the hands, face, and feet may occur The only way to effectively administer hG H is via injection, so the oral preparations amount to little more than expensive feces Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Structure of the Thyroid and Parathyroid Glands (1 of 3) Thyroid Gland—Found in the anterior neck; Right and left lobes are connected by a band called the Isthmus Follicle Cells produce thyroglobulin which becomes triiodothyronine (T3) and tetraiodothyronine (T4) (thyroxine); Thyroglobulin is stored in Colloid, a protein-rich, gelatinous material with iodine atoms Parafollicular Cells are between the thyroid follicles; Produce hormone calcitonin Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Structure of the Thyroid and Parathyroid Glands (2 of 3) Figure 16.14 Anatomy and histology of the thyroid gland Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Structure of the Thyroid and Parathyroid Glands (3 of 3) Figure 16.15 Anatomy of the parathyroid glands Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Thyroid Gland Hormones (1 of 2) Thyroid Hormones—Consist of a hydrophobic amino acid core bound to iodine atoms (uses intracellular receptors) T3 (10%) and T4 (Thyroxine) (90%) Transported in blood bound to thyroxine-binding globulin from the liver 33-40% of T4 converted to T3 in cells Increases protein synthesis Increases rate of glucose, fat, and protein metabolism Essential for normal growth Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Thyroid Gland Hormones (2 of 2) Thyroid Disorders Hyperthyroidism—Overproduction of thyroid hormones; Characterized by weight loss, heat intolerance, disruptions in blood pressure and heart rhythms Figure 16.18 Disorder of thyroid hormone secretion: goiter Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Concept Boost Video: Understanding the Relationship between Negative Feedback Loops and Thyroid Function Use the link below to view AD A compliant video: Concept Boost Video: Understanding the Relationship between Negative Feedback Loops and Thyroid Function [ https://mediaplayer.pearsoncmg.com/assets/_video.tru e/cbvt_thyroid_feedback_loop ] Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Parathyroid Hormone and Bone Homeostasis (1 of 2) Parathyroid Hormone (PT H) Secreted in response to declining blood calcium ion concentration, known as Hypocalcemia Increases the release of calcium ions from bone by stimulating osteoclasts Stimulates the kidneys to form active Vitamin D, which is needed to increase absorption of dietary calcium ions by the small intestine Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.3 Parathyroid Hormone and Bone Homeostasis (2 of 2) Figure 16.19 Maintaining homeostasis: regulation of blood calcium ion concentration by a negative feedback loop Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.4 Structure of the Adrenal Glands (1 of 2) Adrenal Glands—Pyramid-shaped glands located on the superior end of the right and left kidneys; Outer adrenal Cortex surrounding an inner adrenal Medulla Cortex—Typical endocrine gland with three zones that each produce steroid hormones derived from cholesterol Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.4 Structure of the Adrenal Glands (2 of 2) Figure 16.20 Anatomy and histology of the adrenal gland Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.4 Hormones of the Adrenal Cortex (1 of 4) Zones of the Adrenal Cortex Outer Zona Glomerulosa—Secrete mineralocorticoid hormones Aldosterone—Most important Middle Zona Fasciculata—Secrete glucocorticoids and androgenic steroids Cortisol (hydrocortisone)—Most potent Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.4 Hormones of the Adrenal Cortex (2 of 4) Aldosterone—Regulates concentration of sodium, potassium, and hydrogen ions in the body Maintains extracellular concentrations of sodium and potassium which are important in muscles and neurons Maintains blood pressure with other organs through a complex series of interactions called the renin- angiotensin-aldosterone system (RAAS) Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.4 Hormones of the Adrenal Cortex (3 of 4) Figure 16.21 Effects of aldosterone Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.4 Hormones of the Adrenal Cortex (4 of 4) Cortisol—Main role is to help mediate the body’s response to stress Increases fat and protein breakdown and glucose synthesis Decreases inflammation Androgenic Steroids—Steroid sex hormones that affect gonads as well as other tissues Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.4 Hormones of the Adrenal Medulla Adrenal Medulla—Consists of neuroendocrine cells called Chromaffin Cells, which are derived from nervous tissue Secrete Epinephrine and Norepinephrine Increase rate and force of heart contraction Dilate bronchioles in lungs Constrict blood vessels supplying skin, digestive organs, and urinary organs Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.5 Structure of the Pancreas (1 of 2) Pancreas—Club-shaped organ in the abdominal cavity, mostly posterior to the stomach; Includes a rounded Head, middle Body, and thin Tail Pancreatic Islets (Islets of Langerhans)—Secrete hormones into the bloodstream Alpha Cells—Secrete peptide hormone Glucagon Beta Cells—Secrete protein hormone Insulin Delta Cells—Secrete peptide hormone Somatostatin (inhibits secretion of glucagon and insulin) Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.5 Structure of the Pancreas (2 of 2) Figure 16.24 Anatomy and histology of the pancreas Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.5 Hormones of the Endocrine Pancreas: Glucose Homeostasis (1 of 3) Glucagon—Promotes reactions that increase the levels of glucose and other metabolic fuels in the blood; Targets the liver, muscle, and adipose tissue and causes: Glycogenolysis—Breakdown of glycogen into glucose Formation of new glucose by Gluconeogenesis Protein breakdown in muscle tissue to release amino acids for gluconeogenesis Release of fats from adipose tissue for gluconeogenesis and for an additional fuel source Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.5 Hormones of the Endocrine Pancreas: Glucose Homeostasis (2 of 3) Insulin—Promotes uptake of ingested nutrients by its target cells, which lowers the glucose levels in the blood Promotes storage of nutrients in target cells (liver, cardiac and skeletal muscle, and parts of the brain) when not immediately needed Promotion of lipid, amino acid, and glucose uptake Synthesis of glycogen in the liver and skeletal muscle Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.5 Hormones of the Endocrine Pancreas: Glucose Homeostasis (3 of 3) Hypoglycemia—Blood glucose levels too low Causes weakness, dizziness, rapid breathing, nausea, sweating Severe hypoglycemia can cause confusion, hallucinations, seizures, coma, and death Hyperglycemia—Blood glucose levels too high Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 The Thymus: Thymosin and Thymopoietin Thymus—Irregularly shaped organ in the mediastinum; Site of maturation of T Lymphocytes involved in the immune response Secretes the hormones Thymosin and Thymopoietin, which function as paracrine signals that assist in T lymphocyte maturation Larger and more active in infants and children who have developing immune systems Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 The Gonads: Sex Hormones (1 of 2) Gonads—Include the Testes in males and Ovaries in females; Responsible for production of Gametes, or Sperm Cells in males and Ova in females as well as the sex steroid hormones The Testes: Testosterone Stimulates development of secondary male sex characteristics, and has multiple effects on other tissues and organs Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 The Gonads: Sex Hormones (2 of 2) The Ovaries: Estrogens and Progesterone Estrogens are considered the “female hormones” but are produced in small amounts in males Stimulate development of female secondary sex characteristics such as the breasts and the menstrual cycle; and effect other organs, such as bone, blood, kidney, and adipose Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 The Pineal Gland: Melatonin Pineal Gland—Part of the Epithalamus of the diencephalon Secretes the neurohormone Melatonin Trigger appears to be related to light and dark cycles; Begins secreting melatonin when ambient light decreases in the evening, and reaches its peak secretion over night Main target tissues are the sleep-regulating centers in the reticular formation of the brainstem; Appears to adjust the sleep phase of the sleep/wake cycle in some people Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 Adipose Tissue: Leptin Leptin—Protein hormone produced by adipocytes Can cross the blood brain barrier to interact with neurons in the hypothalamus that control feeding Acts on these neurons to induce satiety, a feeling of fullness, that prevents overeating Amount of leptin is related to the amount of adipose tissue Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 Pseudoscience Exposed: Leptin and Obesity Leptin has been heavily researched for its possible pharmaceutical application in weight loss Hypothesis was that leptin supplements would suppress the appetite, which would lead to weight loss Unfortunately, administered leptin was not effective at reducing appetite in humans Many manufacturers of over-the-counter dietary supplements still market their leptin-containing supplements as “miracle weight loss” solutions Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 The Heart: Atrial Natriuretic Peptide Atrial Natriuretic Peptide (AN P)—Produced by cardiac muscle cells in response to stretch-sensitive ion channels AN P targets smooth muscle cells lining blood vessels and causes Vasodilation, which increases vessel diameter AN P also targets kidney tubules and enhances excretion of sodium ions called Natriuresis; This enhances water excretion because it makes the fluid in the tubules more concentrated and water moves into the tubule by osmosis; This lowers blood volume Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 The Kidneys: Erythropoietin Kidneys have several endocrine roles: Erythropoietin (EP O) Production—Secreted mainly by cells of the kidney in response to a decreased level of oxygen in the blood; Acts on red bone marrow to stimulate development of erythrocytes Renin Secretion—Renin is an enzyme in blood that converts the plasma protein angiotensinogen to angiotensin-1; Important part of the renin-angiotensin- aldosterone system which maintains blood pressure Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved 16.6 Hormone-Like Substances Eicosanoids (Mediate inflammatory responses) Prostaglandins Prostacyclins Thromboxanes Leukotrienes Endorphins and Enkephalins (Reduce pain sensation) Growth Factors (Stimulate cell division) Copyright © 2025, 2019, 2016 Pearson Education, Inc. All Rights Reserved