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Download release hormones - Lone Star College
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PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Tenth Edition Shier w Butler w Lewis Chapter 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 13-1 Chapter 13 Endocrine System • Endocrine glands are ductless • Exocrine glands have ducts 13-2 Endocrine Glands Endocrine glands • release hormones • hormones travel through blood to targets Paracrine secretions • act locally • do not travel through blood Autocrine secretions • affect only the secreting cell 13-3 Comparison of Nervous System and Endocrine System • Neurons release neurotransmitters into a synapse, affecting postsynaptic cells • Glands release hormones into the bloodstream • Only target of hormone responds 13-4 Chemistry of Hormones Steroid Hormones • derived from cholesterol • sex hormones • adrenal cortex hormones Nonsteroid Hormones • amines • proteins • peptides • glycoproteins • most hormones 13-5 Structural Formulas of Hormones 13-6 Types of Hormones 13-7 Actions of Steroid Hormones • hormone crosses membranes • hormone combines with receptor in nucleus • synthesis of mRNA activated • mRNA enters cytoplasm to direct synthesis of protein 13-8 Actions of Nonsteroid Hormones • hormone binds to receptor on cell membrane • adenylate cyclase activated • ATP converted to cAMP • cAMP promotes a series of reactions leading to cellular changes 13-9 Prostaglandins • paracrine substances • act locally • very potent in small quantities • regulate cellular responses to hormones • can activate or inhibit adenylate cyclase • wide variety of functions 13-10 Control of Hormonal Secretions • primarily controlled by negative feedback mechanism 13-11 Negative Feedback 13-12 Major Endocrine Glands 13-13 Pituitary Gland Two distinct portions • anterior pituitary (adenohypophysis) • posterior pituitary (neurohypophysis) 13-14 Pituitary Gland Control • Hypothalamic releasing hormones stimulate cells of anterior pituitary to release hormones • Nerve impulses from hypothalamus stimulate nerve endings in the posterior pituitary gland to release hormones 13-15 Hypothalamic Hormones 13-16 Anterior Pituitary Hormones Growth Hormone (GH) • stimulates increase in size and rate of body cells • enhances movement of amino acids through membranes • promotes growth of long bones • secretion inhibited by somatostatin • secretion stimulated by growth hormone-releasing hormone Prolactin (PRL) • sustains milk production after birth • amplifies effect of LH in males • secretion inhibited by prolactin release-inhibiting hormone 13-17 Anterior Pituitary Hormones Thyroid Stimulating Hormone (TSH) • controls secretions of hormones from the thyroid gland • controlled by thyrotropin-releasing hormone Adrenocorticotropic Hormone • controls secretions of some hormones of adrenal cortex • controlled by corticotropin-releasing hormone 13-18 Anterior Pituitary Hormones Follicle-Stimulating Hormone (FSH) • stimulates development of egg-containing follicles in ovaries • stimulates follicular cells to secrete estrogen • stimulates production of sperm cells • controlled by gonadotropin-releasing hormone Luteinizing Hormone (LH) • promotes secretions of sex hormones • stimulates release of egg from ovary • promotes growth of long bones • controlled by gonadotropin-releasing hormone 13-19 Posterior Pituitary Hormones Antidiuretic Hormone (ADH) • causes kidneys to reduce water excretion • in high concentration, raises blood pressure • controlled by hypothalamus in response to changes in blood water concentration and blood volume Oxytocin (OT) • stimulates uterine contractions • stimulates mammary glands to release milk • controlled by hypothalamus in response to stretch in uterine and vaginal walls and stimulation of breasts 13-20 Thyroid Gland 13-21 Thyroid Gland Hormones Thyroxine (T4) and Triiodothyronine (T3) • increases rate of energy release from carbohydrates • increases rate of protein synthesis • accelerates growth • stimulates activity in the nervous system • controlled by TSH Calcitonin • lowers blood calcium and phosphate ion concentrations by inhibiting release of calcium and phosphate from bones • increases rate at which calcium and phosphate are deposited in bones 13-22 Thyroid Gland Disorders General Hyperthyroidism • high metabolic rate • hyperactivity • weight loss • protruding eyes Cretinism • hypothyroidism in infants • leads to small stature and mental retardation 13-23 Thyroid Gland Disorders Myxedema • adult hypothyroidism • low metabolic rate • sluggishness Simple Goiter • deficiency of iodine • leads to deficiency of thyroid hormones • gland enlarges Grave’s disease • overstimulation of gland by antibodies • hyperthyroidism 13-24 Parathyroid Glands 13-25 Parathyroid Hormone • PTH • increases blood calcium levels • decreases blood phosphate levels • stimulates bone resorption by osteoclasts • inhibits osteoblasts • stimulates kidneys to retain calcium and excrete phosphate • promotes calcium absorption into intestine 13-26 Parathyroid Glands Mechanism by which PTH promotes calcium absorption in the intestine 13-27 Parathyroid Gland Disorders Hyperparathyroidism • caused by tumor • fatigue • muscular weakness • altered mental functions • bone weakening Hypoparathyroidism • caused by injury or removal of gland • muscle cramps • seizures • low blood calcium levels 13-28 Adrenal Glands 13-29 Adrenal Medulla Hormones Epinephrine and Norepinephrine • release controlled by sympathetic nervous system • increases heart rate and blood pressure • dilates respiratory airways • promotes breakdown of glycogen • activates reticular formation • increases metabolic rates 13-30 Adrenal Cortex Hormones Aldosterone • increases blood volume and pressure by promoting conservation of sodium ions and water 13-31 Adrenal Cortex Hormones Cortisol • decreases protein synthesis • increases fatty acid release • stimulates glucose synthesis from noncarbohydrates • controlled by CRH from hypothalamus and ACTH from anterior pituitary 13-32 Adrenal Cortex Hormones Adrenal androgens • supplement sex hormones from the gonads • may be converted to estrogen 13-33 Pancreas 13-34 Pancreatic Hormones Glucagon • secreted by alpha cells of pancreatic islets • stimulates liver to break down glycogen • stimulates liver to convert noncarbohydrates into glucose • stimulates break down of fats • controlled by blood glucose concentrations Somatostatin • secreted by delta cells of pancreatic islets • helps regulate carbohydrates 13-35 Pancreatic Hormones Insulin • secreted by beta cells of pancreatic islets • promotes formation of glycogen from glucose • inhibits conversion of noncarbohydrates into glucose • enhances movement of glucose into adipose and muscle cells • decreases blood glucose concentrations • promotes transport of amino acids • enhances synthesis of proteins and fats • controlled by blood glucose concentrations 13-36 Insulin and Glucagon Insulin and glucagon function together to stabilize blood glucose concentrations 13-37 Other Endocrine Glands Pineal Gland • secretes melatonin • regulates circadian rhythms • may control onset of puberty • helps regulate female reproductive cycle Thymus Gland • secretes thymosins • promotes development of certain lymphocytes 13-38 Other Endocrine Glands Reproductive Glands • ovaries secrete estrogen and progesterone • testes secrete testosterone • placenta secretes estrogen, progesterone, and gonadotropins 13-39 Stress Types of Stress • physical stress • psychological stress Responses to Stress • hypothalamus triggers sympathetic impulses to various organs • epinephrine is released • cortisol is released to promote longer-term responses 13-40 Responses to Stress 13-41 Life-Span Changes • endocrine glands shrink • GH levels even out, muscular strength decreases • ADH levels increase due to slow break down • calcitonin levels decrease • PTH increases, osteoporosis risk increases • insulin resistance may develop • changes in melatonin secretion affect the body clock • thymosin production declines increasing risk of infections 13-42 Clinical Application Growth Hormone Ups and Downs • Gigantism - hypersecretion of GH in children • Acromegaly – hypersecretion of GH in adults • Dwarfism – hyposecretion of GH in children 13-43
