Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Xenoestrogen wikipedia , lookup
History of catecholamine research wikipedia , lookup
Mammary gland wikipedia , lookup
Triclocarban wikipedia , lookup
Neuroendocrine tumor wikipedia , lookup
Hyperthyroidism wikipedia , lookup
Hyperandrogenism wikipedia , lookup
Bioidentical hormone replacement therapy wikipedia , lookup
Endocrine disruptor wikipedia , lookup
Ch 16 The Endocrine System: Part A • Acts with nervous system to coordinate and integrate activity of body cells – – • Endocrinology: • Controls and integrates – – • Exocrine glands – • Endocrine glands – • Endocrine glands: pituitary, thyroid, parathyroid, adrenal, and pineal glands • Hypothalamus is Neuroendocrine organ • Some have exocrine and endocrine functions – • Other tissues and organs that produce hormones – • • Pancreas, gonads, placenta Adipose cells, thymus, and cells in walls of small intestine, stomach, kidneys, and heart Chemical Messengers – Hormones: long-distance chemical signals; travel in blood or lymph – Autocrines: chemicals that exert effects on same cells that secrete them – Paracrines: locally acting chemicals that affect cells other than those that secrete them Two main classes of Hormones – Amino acid-based hormones • – Steroids • • Mechanisms of Hormone Action • Target cells – – • Hormone action on target cells may be to – • Hormones act at receptors in one of two ways, depending on their chemical nature and receptor location – Water-soluble hormones (all amino acid–based hormones except thyroid hormone) • Lipid-soluble hormones (steroid and thyroid hormones) • • Target cells must have specific receptors to which hormone binds, for example – • Target Cell Activation – Target cell activation depends on three factors – • – Hormones influence number of their receptors – Up-regulation— – Down-regulation— Control of Hormone Release – Blood levels of hormones • – Endocrine gland stimulated to synthesize and release hormones in response to • • Humoral Stimuli – Changing blood levels of ions and nutrients directly stimulate secretion of hormones – Example: Ca2+ in blood – PTH causes Ca2+ concentrations to rise and stimulus is removed • Neural Stimuli • Hormonal Stimuli – Hormones stimulate other endocrine organs to release their hormones • • Nervous System Modulation – – • Nervous system can override normal endocrine controls Hormones in the Blood – Hormones circulate in blood either free or bound – • Concentration of circulating hormone reflects – • Hormones removed from blood by • • • Half-life—time required for hormone's blood level to decrease by half Onset of Hormone Activity – • • Pituitary gland (hypophysis) has two major lobes – Posterior pituitary (lobe) – Anterior pituitary (lobe) (adenohypophysis) Posterior pituitary (lobe) – • Posterior Pituitary and Hypothalamic Hormones • Oxytocin and ADH • Oxytocin – • ADH (Vasopressin) – • Syndrome of inappropriate ADH secretion (SIADH) • • Anterior Pituitary Hormones – Growth hormone (GH) • – Thyroid-stimulating hormone (TSH) or thyrotropin – Follicle-stimulating hormone (FSH) • – Luteinizing hormone (LH) • – Prolactin (PRL) CH 16 The Endocrine System: Part B • Thyroid Gland -Parafollicular cells produce the hormone calcitonin • Thyroid Hormone (TH) • Actually two related compounds • – T4 (thyroxine); has 2 tyrosine molecules + 4 bound iodine atoms – T3 (triiodothyronine); has 2 tyrosines + 3 bound iodine atoms – Affects virtually every cell in body Thyroid Hormone – – Regulation of tissue growth and development • • • Homeostatic Imbalances of TH – Hyposecretion in adults—myxedema; goiter if due to lack of iodine – Hyposecretion in infants—cretinism – Hypersecretion—Graves' disease Parathyroid Glands – PTH—most important hormone in Ca2+ homeostasis • Parathyroid Hormone • Functions – – • Negative feedback control: rising Ca2+ in blood inhibits PTH release Homeostatic Imbalances of PTH – Hyperparathyroidism due to tumor – Hypoparathyroidism following gland trauma or removal or dietary magnesium deficiency • Adrenal (Suprarenal) Glands – • • Paired, pyramid-shaped organs atop kidneys Structurally and functionally are two glands in one – Adrenal medulla—nervous tissue; part of sympathetic nervous system – Adrenal cortex—three layers of glandular tissue that synthesize and secrete corticosteroids Mineralocorticoids – Regulate electrolytes (primarily Na+ and K+) in ECF • • Aldosterone most potent mineralocorticoid – • Homeostatic Imbalances of Aldosterone – Aldosteronism—hypersecretion due to adrenal tumors – • Glucocorticoids – • Cortisol (hydrocortisone) – • Homeostatic Imbalances of Glucocorticoids – Hypersecretion—Cushing's syndrome/disease • – Hyposecretion—Addison's disease • • Gonadocorticoids (Sex Hormones) • – Hypersecretion – Females and prepubertal males • • • Adrenal Medulla • Adrenal Medulla – • • Hypersecretion • Hyposecretion Pineal Gland – Pinealocytes secrete melatonin, derived from serotonin • • Pancreas – • Glucagon • • • Effects – Glycogenolysis—breakdown of glycogen to glucose – Gluconeogenesis—synthesis of glucose from lactic acid and noncarbohydrates Effects of insulin • • • Factors That Influence Insulin Release – – • Homeostatic Imbalances of Insulin • Diabetes mellitus (DM) – Glycosuria – glucose spilled into urine • Diabetes Mellitus: Signs • Three cardinal signs of DM – Polyuria—huge urine output Polydipsia—excessive thirst Polyphagia—excessive hunger and food consumption • Homeostatic Imbalances of Insulin – Hyperinsulinism: • Ovaries and Placenta • Ovaries produce estrogens and progesterone – Estrogen • Testes produce testosterone – • Other Hormone-producing Structures • Adipose tissue – Leptin – – Resistin – – Adiponectin – • Other Hormone-producing Structures • Enteroendocrine cells of gastrointestinal tract – Gastrin – Secretin – Cholecystokinin – Serotonin acts as paracrine • Other Hormone-producing Structures • Heart – • Kidneys – • Atrial natriuretic peptide (ANP) Erythropoietin Skeleton (osteoblasts) – Osteocalcin • • Skin – Cholecalciferol,