ELAINE N. MARIEB EIGHTH EDITION 9 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings PowerPoint ® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY PART A The Endocrine System

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Endocrine System  Uses chemical messages (hormones) that are released into the blood  Hormones control several major processes  Reproduction  Growth and development  Mobilization of body defenses  Maintenance of much of homeostasis  Regulation of metabolism

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormone Overview  Cells secrete hormones into blood  Blood transfers hormones to target sites  The hormones regulate activity of other cells Types of hormones:  Amino acid-based hormones (proteins)  Steroids – made from cholesterol  Prostaglandins – made from lipids

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Mechanisms of Hormone Action  Hormones affect only certain tissues or organs (target cells or organs)  Hormones can trigger cells to produce certain proteins, enzymes, reactions, cell divisions  Hormone levels in the blood are maintained by negative feedback:  A stimulus or low hormone levels in blood triggers the release of more hormone  Hormone release stops once a certain level in the blood is reached

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormonal Stimuli of Endocrine Glands  Endocrine glands:  Hypothalmus  Pituitary and Pineal glands  Thyroid gland  Thymus gland  Adrenal cortex  Pancreas  Gonads (testis & ovaries Figure 9.2a

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Endocrine  Pituitary Gland: near hypothalamus of brain  Growth Hormone- general metabolism, growth of muscles and bones  Prolactin (PRL)- milk production  Adrenocorticotropic hormone (ACTH)- regulates adrenal glands on-top of kidneys  Thyroid-stimulating hormone (TSH)- growth & activity of thyroid (Immune System)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Other Anterior Pituitary Hormones Pituitary Gland:  Gonadotropic hormones-  Regulate hormonal activity of the gonads  Follicle-stimulating hormone (FSH) Stimulates ovaries and sperm development  Luteinizing hormone (LH) Triggers ovulation and testosterone production

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Posterior Pituitary Pituitary Gland  Oxytocin - stimulates contractions of the uterus during labor, milk ejection  Antidiuretic hormone (ADH)  Triggers kidneys to retain water  Can inhibit urine production  In large amounts, causes raised blood pressure (vasopressin)

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thyroid Gland  Found at the base of the throat  Thyroid hormone- thyroxine has Iodine. Important in metabolism.  Calcitonin- triggers calcium to move from blood into bones. (parathyroid triggers calcium to move from bone to blood) Goiters- not enough iodine

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adrenal Glands Adrenal Glands: sits on top of the kidneys Aldosterone- regulates mineral content in blood, water, and electrolyte balance Glucocorticoids (cortisone and cortisol)- promote normal cell metabolism Sex hormones- androgens (male) and some estrogen (female) Epinephrine & Norepinephrine- prepare the body to deal with short-term stress

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pancreatic Islets Pancreas: The islets of the pancreas produce hormones (formerly called islets of langerhans)  Insulin – allows glucose to move from blood into cells  Glucagon – allows glucose to move from cells into blood  These hormones are antagonists that maintain blood sugar homeostasis Diabetes: issues with insulin hormone

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pineal and Thymus Glands Pineal Gland: found in brain  Melatonin- triggers the body’s wake and sleep cycles Thymus Gland: found under sternum  Thymosin- white blood cells, important in developing the immune system

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Ovaries  Estrogens-  stimulates development of secondary female characteristics, female reproductive organs, prepares uterus to receive a fertilized egg, maintains pregnancy, milk production  Progesterone - produced by the corpus luteum  acts with estrogen to bring about the menstrual cycle, helps in the implantation of an embryo in the uterus

Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Testes Testes  Androgens-  Testosterone is most important androgen. Responsible for male secondary sex characteristics, growth of male reproductive system, sperm production