Chapter 11: 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  Second messenger system of the body  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  Hormones are produced by specialized cells  Cells secrete hormones into extracellular fluids  Blood transfers hormones to target sites  These hormones regulate the activity of other cells Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings The Chemistry of Hormones  Amino acid-based hormones  Proteins  Peptides  Amines  Steroids – made from cholesterol  Prostaglandins – made from highly active 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)  Target cells must have specific protein receptors  Hormone binding influences the working of the cells Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Effects Caused by Hormones  Changes in plasma membrane permeability or electrical state  Synthesis of proteins, such as enzymes  Activation or inactivation of enzymes  Stimulation of mitosis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Steroid Hormone Action  Diffuse through the plasma membrane of target cells  Enter the nucleus  Bind to a specific protein within the nucleus  Bind to specific sites on the cell’s DNA  Activate genes that result in synthesis of new proteins Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Steroid Hormone Action PRESS TO PLAY STEROID HORMONE ANIMATION Figure 9.1a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nonsteroid Hormone Action  Hormone binds to a membrane receptor  Hormone does not enter the cell  Sets off a series of reactions that activates an enzyme  Catalyzes a reaction that produces a second messenger molecule  Oversees additional intracellular changes to promote a specific response Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Nonsteroid Hormone Action PRESS TO PLAY NONSTEROID HORMONE ANIMATION Figure 9.1b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Control of Hormone Release  Hormone levels in the blood are maintained by negative feedback  A stimulus or low hormone levels in the blood triggers the release of more hormone  Hormone release stops once an appropriate level in the blood is reached Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormonal Stimuli of Endocrine Glands  Endocrine glands are activated by other hormones Figure 9.2a Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Humoral Stimuli of Endocrine Glands  Changing blood levels of certain ions stimulate hormone release Figure 9.2b Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Neural Stimuli of Endocrine Glands  Nerve impulses stimulate hormone release  Most are under control of the sympathetic nervous system Figure 9.2c Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Location of Major Endrocrine Organs Figure 9.3 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pituitary Gland  Size of a grape  Hangs by a stalk from the hypothalamus  Protected by the sphenoid bone  Has two functional lobes  Anterior pituitary – glandular tissue  Posterior pituitary – nervous tissue Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Anterior Pituitary  Six anterior pituitary hormones  Two affect non-endocrine targets  Four stimulate other endocrine glands (tropic hormones)  Characteristics of all anterior pituitary hormones  Proteins (or peptides)  Act through second-messenger systems  Regulated by hormonal stimuli, mostly negative feedback Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Anterior Pituitary Figure 9.4 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Growth Hormone (GH)  General metabolic hormone  Major effects are directed to growth of skeletal muscles and long bones  Causes amino acids to be built into proteins  Causes fats to be broken down for a source of energy Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Other Anterior Pituitary Hormones  Prolactin (PRL)  Stimulates and maintains milk production following childbirth  Function in males is unknown  Adrenocorticotropic hormone (ACTH)  Regulates endocrine activity of the adrenal cortex  Thyroid-stimulating hormone (TSH)  Influences growth and activity of the thyroid Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Other Anterior Pituitary Hormones  Gonadotropic hormones  Regulate hormonal activity of the gonads  Follicle-stimulating hormone (FSH)  Stimulates follicle development in ovaries  Stimulates sperm development in testes Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Other Anterior Pituitary Hormones  Gonadotropic hormones (continued)  Luteinizing hormone (LH)  Triggers ovulation  Causes ruptured follicle to become the corpus luteum  Stimulates testosterone production in males  Referred to as interstitial cell- stimulating hormone (ICSH) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pituitary - Hypothalamus Relationship  Release of hormones is controlled by releasing and inhibiting hormones produced by the hypothalamus  Hypothlamus produces two hormones that are transorted to neurosecretory cells of the posterior pituitary  The poterior pituitary is not strictly an endocrine gland, but does release hormones Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Posterior Pituitary  Oxytocin  Stimulates contractions of the uterus during labor  Causes milk ejection  Antidiuretic hormone (ADH)  Can inhibit urine production  In large amounts, causes vasoconstriction leading to increased blood pressure (vasopressin) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Posterior Pituitary Figure 9.5 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings  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 Thyroid Gland  Found at the base of the throat  Consists of two lobes and a connecting isthmus  Produces two hormones  Thyroid hormone  Calcitonin Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thyroid Gland Figure 9.6 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thyroid Hormone  Major metabolic hormone  Composed of two active iodine-containing hormones  Thyroxine (T4) – secreted by thyroid follicles  Triiodothyronine (T3) – conversion of T4 at target tissues Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Calcitonin  Decreases blood calcium levels by causing its deposition on bone  Antagonistic to parathyroid hormone  Produced by C (parafollicular) cells Figure 9.9 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Parathyroid Glands  Tiny masses on the posterior of the thyroid  Secrete parathyroid hormone  Stimulate osterclasts to remove calcium from bone  Stimulate the kidneys and intestine to absorb more calcium  Raise calcium levels in the blood Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Adrenal Glands  Two glands  Cortex – outer glandular region in three layers  Medulla – inner neural tissue region  Sits on top of the kidneys Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Adrenal Cortex  Mineralocorticoids (mainly aldosterone)  Produced in outer adrenal cortex  Regulate mineral content in blood, water, and electrolyte balance  Target organ is the kidney  Production stimulated by renin and aldosterone  Production inhibited by atrial natriuretic peptide Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Adrenal Cortex Figure 9.10 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Adrenal Cortex  Glucocorticoids (including cortisone and cortisol)  Produced in the middle layer of the adrenal cortex  Promote normal cell metabolism  Help resist long-term stressors  Released in response to increased blood levels of ACTH Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Adrenal Cortex  Sex hormones  Produced in the inner layer of the adrenal cortex  Androgens (male) and some estrogen (female) Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Adrenal Medulla  Produces two similar hormones (catecholamines)  Epinephrine  Norepinephrine  These hormones prepare the body to deal with short-term stress Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Roles of the Hypothalamus and Adrenal Glands in the Stress Response Figure 9.12 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pancreatic Islets  The pancreas is a mixed gland  The islets of the pancreas produce hormones  Insulin – allows glucose to cross plasma membranes into cells from beta cells  Glucagon – allows glucose to enter the blood from alpha cells  These hormones are antagonists that maintain blood sugar homeostasis Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pancreatic Islets Figure 9.13 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pancreatic Hormones and Blood Sugar Figure 9.14 Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Pineal Gland  Found on the third ventricle of the brain  Secretes melatonin  Helps establish the body’s wake and sleep cycles  May have other as-yet-unsubstantiated functions Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Thymus  Located posterior to the sternum  Largest in infants and children  Produces thymosin  Matures some types of white blood cells  Important in developing the immune system Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Ovaries  Estrogens  Produced by Graafian follicles or the placenta  Stimulates the development of secondary female characteristics  Matures female reproductive organs  Helps prepare the uterus to receive a fertilized egg  Helps maintain pregnancy  Prepares the breasts to produce milk Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Hormones of the Ovaries  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  Interstitial cells of testes are hormone- producing  Produce several androgens  Testosterone is the most important androgen  Responsible for adult male secondary sex characteristics  Promotes growth and maturation of male reproductive system  Required for sperm cell production Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Other Hormone-Producing Tissues and Organs  Parts of the small intestine  Parts of the stomach  Kidneys  Heart  Many other areas have scattered endocrine cells Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Endocrine Function of the Placenta  Produces hormones that maintain the pregnancy  Some hormones play a part in the delivery of the baby  Produces HCG in addition to estrogen, progesterone, and other hormones Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Developmental Aspects of the Endocrine System  Most endocrine organs operate smoothly until old age  Menopause is brought about by lack of efficiency of the ovaries  Problems associated with reduced estrogen are common  Growth hormone production declines with age  Many endocrine glands decrease output with age Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings