Endocrine System PDF

9 PART A The Endocrine System PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS...

9 PART A The Endocrine System PowerPoint® Lecture Slide Presentation by Jerry L. Cook, Sam Houston University ESSENTIALS OF HUMAN ANATOMY & PHYSIOLOGY EIGHTH EDITION ELAINE N. MARIEB Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  The Endocrine System Signaling molecules sent out by the endocrine system are called hormones Hormones may have effects in a single location or throughout the body Only cells with receptors for a certain hormone can respond to it The endocrine system is well adapted for coordinating gradual changes that affect the entire body © 2016 Pearson Education, Inc.  Hormone Overview Hormones are produced by specialized cells in endocrine glands Cells secrete hormones into interstitial fluid Blood transfers hormones to target sites These hormones regulate the activity of other cells. What type of (a) Signaling by hormones signaling was STIMULUS Endocrine this? cell Hormone Signal travels everywhere. Long-distance: Called “endocrine” or Blood vessel hormonal signaling Response Hormones control several major processes – Reproduction – Growth and development – Mobilization of body defenses – Maintenance of much of homeostasis (electrolyte, water and nutrient balance of the blood) – Regulation of metabolism © 2 Thyroid gland Pineal gland Hypothalamus Thyroid hormone (T3 and T4 ) Melatonin 0 Calcitonin 1 6 Pituitary gland P Parathyroid glands Posterior pituitary e Parathyroid hormone (PTH) Oxytocin a Vasopressin, also r Adrenal glands (atop kidneys) called antidiuretic Adrenal medulla hormone (ADH ) s Epinephrine and norepinephrine o Anterior pituitary Adrenal cortex Follicle-stimulating n Glucocorticoids hormone (FSH) E Mineralocorticoids Luteinizing d hormone (LH) u Thyroid-stimulating Ovaries (in females) hormone (TSH) c Adrenocorticotropic Estrogens a Progesterone hormone (ACTH) t Prolactin i Growth hormone (GH) Testes (in males) Melanocyte-stimulating o Androgens hormone (MSH) n , Pancreas I Insulin Glucagon n c  Mechanisms of Hormone Action Hormones affect only certain tissues or organs (target cells or organs) Target cells must have specific protein receptors to be affected by a hormone Hormone binding influences the working of the cells Think of the binding of hormone to target cell like puzzle pieces fitting together.  Hormone Solubility Nonsteroidal hormones are soluble in water but not in lipids These hormones cannot pass through the plasma membrane of target cells Instead, they bind to cell-surface receptors, and that triggers events leading to a cellular response The intracellular response is called signal transduction A signal transduction pathway typically has multiple steps  Steroidal hormones are lipid soluble and bind to receptors inside cells When bound by the hormone, the hormone- receptor complex moves into the nucleus There, the receptor alters transcription of particular genes © 2016 Pearson Education, Inc.. Multiple Effects of Hormones Many hormones elicit more than one response For example, epinephrine is secreted by the adrenal glands and can raise blood glucose levels, increase blood flow to muscles, and decrease blood flow to the digestive system Target cells vary in their response to a hormone because they differ in their receptor types or in the molecules that produce the response © 2 (a) Liver cell (b) Smooth muscle cell (c) Smooth muscle cell 0 in wall of blood in wall of blood 1 vessel that supplies vessel that supplies 6 skeletal muscle intestines P Epinephrine Epinephrine Epinephrine e a b receptor b receptor a receptor r Glycogen s deposits o n E d u Glucose c a t Glycogen breaks down Cell relaxes. Cell contracts. i and glucose is released o from cell. n Blood vessel dilates, Blood vessel , Blood glucose level increasing flow to constricts, decreasing I increases. skeletal muscle. flow to intestines. n c  Regulating and Conforming An animal that is a regulator uses internal mechanisms to control internal change despite external fluctuation An animal that is a conformer allows its internal condition to change in accordance with external changes  40 River otter (temperature regulator) Body temperature (C) 30 20 Largemouth bass (temperature conformer) 10 0 0 10 20 30 40 Ambient (environmental) temperature (C)  Animals achieve homeostasis by maintaining a variable at or near a particular value, or set point Fluctuations above or below the set point serve as a stimulus; these are detected by a sensor and trigger a response The response returns the variable to the set point © 2016 Pearson Education, Inc.  NORMAL RANGE for internal variable Response Stimulus: change in internal variable Control center Sensor  Homeostasis in animals relies largely on negative feedback, a control mechanism that reduces the stimulus (positive feedback reinforces a stimulus to increase the response) Homeostasis moderates, but does not eliminate, changes in the internal environment Set points and normal ranges for homeostasis are usually stable, but certain regulated changes in the internal environment are essential © 2016 Pearson Education, Inc.. Response: Blood vessels in skin dilate. Thermostat in hypothalamus activates cooling mechanisms. Response: Sweat Body temperature Body temperature increases. decreases. NORMAL BODY TEMPERATURE (approximately 36–38C) Body temperature Body temperature increases. decreases. Response: Shivering Thermostat in hypothalamus Response: Blood activates warming vessels in skin mechanisms. constrict.  Thermostat turns heater off. Room temperature Room temperature increases. decreases. ROOM TEMPERATURE AT 20C (set point) Room temperature Thermostat Room temperature increases. turns decreases. heater on.