DOCSLIB.ORG

The Endocrine and Reproductive System: Adverse Effects of Hormonally Active Substances?

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
The Endocrine and Reproductive System: Adverse Effects of Hormonally Active Substances? The Endocrine and Reproductive System: Adverse Effects of Hormonally Active Substances? Helmut A. Greim, MD ABSTRACT. Chemicals that have the intrinsic property Our Fertility, Intelligence, and Survival? A Scientific to modulate or even disrupt the endocrine system are Detective Story. present in the human environment. Because it is the Originally, Carlsen et al2 evaluated a total of 61 potency of such chemicals that determines the toxicologic studies on sperm count and established that there relevance, assessment of the risk to human health must was a decrease from 113 million to 66 million consider both the endocrine disrupting potential and the potency. Usually in vitro assays are applied to detect the sperm/ml of semen between 1938 and 1990. On this 3 potential of a hormone-like effect, and such data are basis, Sharpe and Skakkebaek presented the hy- considered useful to set priorities for additional testing pothesis that the dysfunctions and diseases of the and for mechanistic studies. However, such data allow male sex organs (as testicular cancer, malformations only determination of relative potency of a chemical as of the urethra, or cryptorchidism), which have been compared with other xenobiotics, natural compounds, or described with increasing frequency in the course of endogenous hormones. Relevant information on the en- the past 3 to 5 decades, could be associated with docrine-disrupting potency can be taken only from in chemicals that mimic the action of estrogen. In par- vivo assays, eg, the Hershberger (male reproductive or- gans) and uterotrophic (female reproductive organs) as- ticular, medications that mimic the action of estro- says, the updated versions of the 28- and 90-day toxicity gen, phytoestrogens, estrogens in cow milk, and cer- studies in rodents, and the 2-generation studies in ro- tain industrial chemicals have been considered. This dents. With the use of this information and the concen- assumption is supported by observations in wild tration of these chemicals in humans, the potency of the animals. Dichlorodiphenyltrichloroethane (DDT), for effect as compared with endogenous hormone activity example, accumulated in the bodies of birds of prey, can be estimated. So far, the relative potencies of chem- which are at the end of the food chain, and led to icals tested in in vitro systems as compared with estradiol reproductive disorders. Colborn et al4 described are several orders of magnitude smaller, whereas potency of the phytoestrogen, eg, isoflavones such as genistein or smaller penises in alligators and unfertilized eggs daidzein, can even exceed that of estradiol, especially in that had been laid as the result of an industrial infants who are fed soy-based formula as a sole source of accident in Florida, in which large quantities of the nutrition. Although there are still open questions regard- insecticide dicofol were discharged into a lake. In ing in utero or early postnatal exposure, the low poten- other regions, more female than male offspring were cies and concentrations of manmade chemicals as com- counted in several species of fish and the gulls that pared with the endogenous hormones in humans make it ate these fish. These observations and hypotheses unlikely that adverse effects occur at common exposure. resulted in a multitude of studies to identify hormon- Pediatrics 2004;113:1070–1075; endocrine disrupters, xe- ally active chemicals and to explain their mechanism noestrogens, phytoestrogens, adverse effects, test systems. of action and their significance for humans and the environment. ABBREVIATIONS. DDT, dichlorodiphenyltrichloroethane; PCB, The different effects have been described and dis- polychlorinated biphenyl; OECD, Organisation for Economic Co- cussed by various authors and committees,5–14 as operation and Development. have the consequences for appropriate testing.15,16 A continuous flow of reports describe an association of eports of decreased sperm counts and in- chemical exposure of children to hormone-related creased incidences of testicular cancer in men disorders. These are birth defects, developmental Rand breast tumors in women have aroused disorders, declining proportion of male newborns, intense discussions in the general public and the neuromental deficits in families of pesticide work- scientific community. This became common knowl- ers,17,18 testicular dysgenesis syndrome as a result of edge in 1996 with the publication of the book by disruption of embryonal programming and gonadal Colborn et al,1 Our Stolen Future: Are We Threatening development during fetal life by adverse environ- mental influences,19 and insufficient androgen action From the Institute of Toxicology and Environmental Hygiene, Technical in the male fetus with subsequent undervirilization University of Munich, Munich, Germany. and hypospadias in the newborn as a result of intra- Received for publication Oct 7, 2003; accepted Oct 20, 2003. uterine exposure to environmental hormonal disrup- Reprint requests to (H.A.G.) Institute of Toxicology and Environmental tors.20 However, except for high-exposure scenarios ␤ Hygiene, Technical University of Munich, Hohenbachernstra e 15–17, such as Yusho disease after high exposure to poly- D-85354 Freising-Weihenstephan. E-mail: [email protected] PEDIATRICS (ISSN 0031 4005). Copyright © 2004 by the American Acad- chlorinated biphenyls (PCBs), dibenzodioxins, and emy of Pediatrics. dibenzofurans,21,22 none of these suggested associa- 1070 PEDIATRICS Vol.Downloaded 113 No. 4 from April www.aappublications.org/news 2004 by guest on September 30, 2021 tions demonstrated a sufficiently robust correlation Replacement of a physiologic ligand, eg, an estro- between exposure and effects, so, increasingly, other gen from the receptor by a competitor, eg, a xe- causes for the observed effects are discussed, such as noestrogen, depends on its relative affinity to the sociodemographic characteristics23 or combinations receptor and its concentration. For example, replace- of Ͼ1 problem.19 ment of the physiologic ligand from the receptor by It is impossible to review all information and add a compound of 1000-fold lower affinity requires a to the elaborate reports of the different review pan- 1000-fold higher concentration. Although this over- els. Therefore, possible mechanisms and criteria to simplifies competitive interaction of compounds at a evaluate the plausibility of a correlation between receptor, it demonstrates the need for information on adverse effects in children and exposure to endo- the relative binding affinities of the compounds in crine-disrupting chemicals are described. question and their concentration in the organism. The Scientific Committee on Toxicology, Ecotoxi- cology and the Environment of the European Com- SUBSTANCES THAT MIMIC THE ACTION OF mission has compared the potency of xenoestrogen HORMONES concentrations detected in human blood as a surro- In principle, an “endocrine disrupter” is defined as gate for concentrations at the receptor with the po- an exogenous substance or mixture that alters func- tency of estradiol concentrations in blood.7 It seemed tion(s) of the endocrine system and consequently that the relative potency of o,pЈ-DDT, 4-nonylphenol causes adverse health effects in an intact organism, or bisphenol A are approximately 1 million-fold or its progeny, or (sub)populations.7,24 In the case of lower than that of estradiol. Only the phytoestrogen xenoestrogens, it is the stimulation of mitotic activity genistein showed a potency that exceeded that of in the tissue of the female genital tract. Many chem- estradiol. From this it was concluded that an inter- icals that humans ingest with their diet have estro- action of the compounds at the receptor with phys- gen-like effects, which have been identified in a mul- iologic consequences is unlikely. titude of test systems.25 Among them are industrial In addition to the reproductive organs, the liver, chemicals such as certain herbicides, fungicides, or- kidney, adrenal gland, central nervous system, im- ganochlorine insecticides, nematocides, organophos- mune system, cardiovascular system, and bones are phates, pyrethroids, heavy metals, PCBs, and phtha- target tissues of the effect of steroid hormones. The lates. Colborn et al4 compiled 45 chemicals, including corresponding receptors have been identified in the PCBs, dibenzodioxins, dibenzofurans, and DDT, these tissues. Moreover, there are indications of a to which they attribute an influence on the reproduc- concentration-dependent stimulation (low concen- tive system in humans. Also included are the phy- trations) or inhibition (high concentrations) of tumor toestrogens, ie, naturally occurring plant substances. growth by steroid hormones.10,26,27 Interaction with endogenous hormones may occur via different mechanisms. Xenobiotics can influence TEST SYSTEMS FOR IDENTIFICATION OF hormone synthesis—the release, the transport, the ENDOCRINE-DISRUPTING CHEMICALS effect, the metabolism, and the excretion of hor- A great variety of test systems are being used with mones. Another group of natural and synthetic sub- different experimental modifications, which makes it stances interferes with the hormones at receptors. difficult to compare the results directly.15,25 In most Phytoestrogens such as coumestrol, daidzein, and cases, standardization is required. The in vitro tests genistein; medications such as diethylstilbestrol, are able to identify the intrinsic hormone-like poten- ethinyl estradiol, and tamoxifen; and industrial
Load more

Recommended publications
  • Chapter 45-Hormones and the Endocrine System Pathway Example – Simple Hormone Pathways Stimulus Low Ph in Duodenum
    Chapter 45-Hormones and the Endocrine System Pathway Example – Simple Hormone Pathways Stimulus Low pH in duodenum •Hormones are released from an endocrine cell, S cells of duodenum travel through the bloodstream, and interact with secrete secretin ( ) Endocrine the receptor or a target cell to cause a physiological cell response Blood vessel A negative feedback loop Target Pancreas cells Response Bicarbonate release Insulin and Glucagon: Control of Blood Glucose Body cells •Insulin and glucagon are take up more Insulin antagonistic hormones that help glucose. maintain glucose homeostasis Beta cells of pancreas release insulin into the blood. The pancreas has clusters of endocrine cells called Liver takes islets of Langerhans up glucose and stores it as glycogen. STIMULUS: Blood glucose Blood glucose level level declines. rises. Target Tissues for Insulin and Glucagon Homeostasis: Blood glucose level Insulin reduces blood glucose levels by: (about 90 mg/100 mL) Promoting the cellular uptake of glucose Blood glucose STIMULUS: Slowing glycogen breakdown in the liver level rises. Blood glucose level falls. Promoting fat storage Alpha cells of pancreas release glucagon. Liver breaks down glycogen and releases glucose. Glucagon Glucagon increases blood glucose levels by: Stimulating conversion of glycogen to glucose in the liver Stimulating breakdown of fat and protein into glucose Diabetes Mellitus Type I diabetes mellitus (insulin-dependent) is an autoimmune disorder in which the immune system destroys pancreatic beta cells Type II diabetes
    [Show full text]
  • Biology F – Lesson 4 – Endocrine & Reproductive Systems
    Unit: Biology F – Endocrine & Reproduction LESSON 4.1 - AN INTRODUCTION TO THE ENDOCRINE SYSTEM Overview: Students research the location and function of the major endocrine glands and consider some endocrine system disorders. Suggested Timeline: 1 hour Materials: • An Introduction to the Endocrine System (Student Handout) • QUIZ – The Endocrine System (Student Handout) • student access to computers with the internet Method: 1. Allow students to use computers with internet access and other resources from the library to complete their questions on the endocrine system. 2. Students write quiz on the endocrine system. Assessment and Evaluation: • Affective assessment of student understanding of parts of the endocrine system • Student grade on quiz Extension: Assign a student or group of students to ‘be’ a specific endocrine gland. Have them role play for the class to get the idea of the function of the gland across to their classmates. Science 21 Bio F – Endocrine B152 Unit: Biology F – Endocrine & Reproduction Student Handout Name: ______________ Partner(s): _________________________ Date: ____________ Period: _____ An Introduction to the Endocrine System Go to the following website: http://health.howstuffworks.com/adam-200091.htm Watch the video to complete the following questions. 1. The endocrine system is composed primarily of _________________ that produce chemical messengers called __________________. 2. List the names of glands of the endocrine system, as mentioned in the video. Hint: There are 8 in total. 3. The endocrine and ________________ systems work closely together. The brain sends info to the endocrine glands and the endocrine glands send feedback to the brain. 4. The part of the brain that is known as the ‘master switchboard’ and controls the endocrine system is called the _____________________.
    [Show full text]
  • Chapter 20: Endocrine System
    EndocrineEndocrine SystemSystem Modified by M. Myers 1 TheThe EndocrineEndocrine SystemSystem 2 EndocrineEndocrine GlandsGlands z The endocrine system is made of glands & tissues that secrete hormones. z Hormones are chemicals messengers influencing a. metabolism of cells b. growth and development c. reproduction, d. homeostasis. 3 HormonesHormones Hormones (chemical messengers) secreted into the bloodstream and transported by blood to specific cells (target cells) Hormones are classified as 1. proteins (peptides) 2. Steroids 4 HormoneHormone ClassificationClassification z Steroid Hormones: – Lipid soluble – Diffuse through cell membranes – Endocrine organs z Adrenal cortex z Ovaries z Testes z placenta 5 HormoneHormone ClassificationClassification z Nonsteroid Hormones: – Not lipid soluble – Received by receptors external to the cell membrane – Endocrine organs z Thyroid gland z Parathyroid gland z Adrenal medulla z Pituitary gland z pancreas 6 HormoneHormone ActionsActions z “Lock and Key” approach: describes the interaction between the hormone and its specific receptor. – Receptors for nonsteroid hormones are located on the cell membrane – Receptors for steroid hormones are found in the cell’s cytoplasm or in its nucleus 7 http://www.wisc- online.com/objects/index_tj.asp?objID=AP13704 8 EndocrineEndocrine SystemSystem z There is a close assoc. b/w the endocrine & nervous systems. z Hormone secretion is usually controlled by either negative feedback or antagonistic hormones that oppose each other’s actions 9 HypothalamusHypothalamus 1. regulates the internal environment through the autonomic system 2. controls the secretions of the pituitary gland. 10 HypothalamusHypothalamus && PituitaryPituitary GlandGland posteriorposterior pituitary/pituitary/ anterioranterior pituitarypituitary 11 PosteriorPosterior PituitaryPituitary The posterior pituitary secretes zantidiuretic hormone (ADH) zoxytocin 12 13 14 AnteriorAnterior pituitarypituitary glandgland 1.
    [Show full text]
  • 210825 Endocrine System 5 – the Function of the Pineal and Thymus
    Copyright EMAP Publishing 2021 This article is not for distribution except for journal club use Clinical Practice Keywords Endocrine system/ Hormones/Pineal gland/Thymus gland Systems of life This article has been Endocrine system double-blind peer reviewed In this article... ● Endocrine functions of the pineal and thymus glands ● Hormones secreted by the pineal and thymus glands ● Role of the pineal and thymus glands in mediating essential physiological processes Endocrine system 5: the function of the pineal and thymus glands Key points Authors John Knight is associate professor in biomedical science; Zubeyde Bayram- The pineal gland is Weston is senior lecturer in biomedical science; Maria Andrade is honorary associate a neuroendocrine professor in biomedical science; all at College of Human and Health Sciences, gland in the brain, Swansea University. which produces the hormone melatonin Abstract The endocrine system consists of glands and tissues that produce and secrete hormones to regulate and coordinate vital bodily functions. This article, the Melatonin is key to fifth in an eight-part series on the endocrine system, explores the anatomy and synchronising the physiology of the pineal and thymus glands, and describes how they regulate and body’s biological coordinate vital physiological processes in the body through hormonal action. rhythms and has an influence on Citation Knight J et al (2021) Endocrine system 5: pineal and thymus glands. immunity Nursing Times [online]; 117: 9, 54-58. The thymus has both immune and he endocrine system comprises with a rich blood flow of around 4ml/ endocrine functions, glands and tissues that produce min/g, second only to that of the kidneys.
    [Show full text]
  • The Endocrine System from Our Neurotransmitter Chapter: Endocrine Neurotransmitters Convey a Message from the Glands Secrete Sending Neuron to the Receiving Neuron(S)
    11/10/2014 The Endocrine System From Our Neurotransmitter Chapter: Endocrine Neurotransmitters convey a message from the glands secrete sending neuron to the receiving neuron(s). “hormones” Hormones, on the other hand, “broadcast” a message directly into throughout the body via the bloodstream, so are able bloodstream. to influence cells in many distant organs/tissues. But we’ll hold off on hormones for the moment, In Chap 11 the because before there could be hormones, there had Hypothalamus, to be genes to develop the glands. Pituitary, Gonads, and Adrenal glands will play a role in sexuality What defines male or female ? Sexual Differentiation in Mammals (Chap 11) How do we become the sexual individuals we are? Differentiation Role of Sex Chromosomes • Genetic sex (XX or XY) is determined by the sperm (X-bearing or Y-bearing) that fertilizes the egg. • Early gonads have potential to be either ovaries or testes for ~6 weeks. • Sex-determining region of the Y chromosome (SRY) is a gene producing a *protein causing the middle of baby gonads to become testes. • If testes develop, they begin to produce androgens like testosterone. • If SRY gene is not present, the outside of the early gonads turns into ovaries. *sometimes called testis-determining factor 1 11/10/2014 Experimental Evidence • Removal of SRY gene from Y XY mouse develops as a female • Add SRY gene to X XX mouse develops as a male • Injection of SRY’s protein in genetic female develops testes • Inject genetic male with drug that blocks the SRY’s protein develops ovaries Figure 13.6 Endocrine Glands – Release hormones directly into bloodstream Although the pituitary is sometimes called the “master gland” in Organizational Effects fact the hypothalamus is the “master” of the pituitary.
    [Show full text]
  • Endocrine System 4: Adrenal Glands
    Copyright EMAP Publishing 2021 This article is not for distribution except for journal club use Clinical Practice Keywords Endocrine system/ Hormones/Adrenal glands Systems of life This article has been Endocrine system double-blind peer reviewed In this article... ● Endocrine functions of the adrenal glands ● Hormones of the adrenal glands ● The role of adrenal gland hormones in mediating essential physiological processes Endocrine system 4: adrenal glands Key points Authors Maria Andrade is honorary associate professor in biomedical science; There are two Zubeyde-Bayram Weston is senior lecturer in biomedical science; John Knight is adrenal glands: one associate professor in biomedical science; all at College of Human and Health located above each Sciences, Swansea University. kidney NT SELF- Abstract The endocrine system consists of glands and tissues that produce and ASSESSMENT Adrenal glands secrete hormones to regulate and coordinate vital bodily functions. This article, the Test your consist of two parts, fourth in an eight-part series on the endocrine system, explores the anatomy and knowledge. the cortex and the physiology of the adrenal glands, and describes how they regulate and coordinate After reading this medulla, which each vital physiological processes in the body through hormonal action. article go to produce different nursingtimes.net/ NTSAAdrenal hormones Citation Andrade M et al (2021) Endocrine system 4: adrenal glands. Nursing Times If you score 80% [online]; 117: 8, 54-58. or more, you will The adrenal cortex receive a certificate produces a diverse that you can use range of steroid as revalidation his eight-part series on the endo- colour and are positioned retroperito- evidence.
    [Show full text]
  • 1 General Overview of the Endocrine System Questions to Be Thinking
    General Overview of the Endocrine System Questions to be thinking about to help organize your learning of the components of the Endocrine System: Anatomy 1) Where are the different hormone producing cells located? 2) What hormone does a particular type of endocrine cell or neuron produce? General Overview of the Endocrine System Questions to be thinking about to help organize your learning of the components of the Endocrine System: Hormones 1) What is their general chemical structure? 2) How does their structure affect their function? 3) Where are they produced? 4) What environmental or physiological stimuli regulate their production and secretion? 5) Is their production and secretion under direct neural or hormonal control? 6) What are their targets? 7) What effects do they produce on their targets? 8) How do they produce their effects on their targets (how is the signal transduced? i.e. receptor mechanisms) 1 Often endocrine cells are clumped together into a well defined gland (e.g. pituitary, thyroid, adrenal, testes, ovaries), but not always (e.g. gut, liver, lung). Often endocrine cells are clumped together into a well defined gland (e.g. pituitary, thyroid, adrenal, testes, ovaries), but not always (e.g. gut, liver, lung). Remember, it's cells that produce hormones, not glands. Although many glands secrete more than one type of hormone, most neurons or endocrine cells only produce one type of hormone (there are a few exceptions). 2 Some Terminology Neurohormone: a hormone that is produced by a neuron Some Terminology All of the hormones we discuss can be classified as belonging to one of 2 general functional categories: 1] Releasing hormone (or factors) — hormone that acts on endocrine cells to regulate the release of other hormones.
    [Show full text]
  • Endocrine System
    Human Body Series Endocrine System Quiz Answer Key 1. List five functions of the endocrine system: Any five of the following: regulating mood, growth and development; tissue function; the fight or flight response; metabolism; blood glucose levels; sexual function and reproductive processes. 2. In general, the endocrine system is in charge of body processes that happen slowly, such as cell growth. Faster processes like breathing and body movement are controlled by the nervous system . 3. The brain contains these three glands: pituitary gland, hypothalamus , pineal gland (or pineal body) . 4. Hormones are chemical messengers that transfer information and instructions from one set of cells to another. 5. Once a hormone is secreted, it travels from the endocrine gland that produced it through the bloodstream to the cells designed to receive its message. These cells are called target cells . 6. The pancreas produces two important hormones, insulin and glucagon . 7. If the pancreas doesn’t produce enough insulin, the result is diabetes . 8. Parathyroid hormone controls the level of calcium in the blood. 9. The thyroid gland is involved in metabolism , the process by which the fuel in the food we eat is converted into cellular energy. 10. When hormone levels reach a certain normal amount in the blood, the endocrine system has a built-in turnoff process. It is called negative feedback system . 11. Endocrine glands release more than 20 major hormones directly into the bloodstream. 12. The pineal gland secretes melatonin . 13. If the pituitary glands release hormones that stimulate the gonads to produce sex hormones too early, some kids may experience precocious puberty and begin to go through puberty at a very young age.
    [Show full text]
  • The Endocrine System Dr
    The Endocrine System Dr. Ali Ebneshahidi Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Endocrine System . The endocrine system interacts with the nervous system to coordinate and integrate body activities by means of hormones . Endocrine tissues and organs secrete hormone into body fluids (mainly blood and lymph) directly using diffusion. Exocrine tissues, such as salivary glands, and sebaceous glands, secrete chemical substances through ducts into an open space. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Five major functions of hormones . a) Regulate metabolic processes (e.g. thyroid hormones). b) Control the rate of chemical reactions (e.g. growth hormone). c) Aid in the transport of substances across the cell membrane of target cells (e.g. insulin and glucagon). d) Regulate water and electrolyte balances (e.g. antidiurectic hormone, calcitonin, and aldosterone). e) Play a vital role in reproduction, growth and development (e.g. estrogens , progesterone, and testosterone). Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Major Endocrine Organs Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Chemistry of Hormones . Hormones are organic compounds secreted by endocrine glands, that have a potent effect in target cells Two types of hormones: . a) Protein hormones: made of amino acids joined by peptide bonds. fat – insoluble; as a result cannot diffuse across the membrane of target cells . most hormones belong to this group except hormones secreted by the gonads (testis and ovary) and the adrenal cortex. b) Steroid hormones: made of fatty acids using cholesterol as a functional group. Fat-soluble; as a result can diffuse into target cells .
    [Show full text]
  • Hths 2231 - Lab 9 Endocrine System Pathophysiology
    Hths 2231 - Lab 9 Endocrine System Pathophysiology Activity #1 Diabetes Movie Questions 1. Type I diabetes, found in children, is also called ____________, ______________, or _______________. 2. Insulin is needed for ____________ to penetrate ___________. 3. List 2 differences between Type I and Type II diabetes. 4. Type I diabetes is treated with ______________________. 5. Diabetics have a _____________ predisposition which is triggered by ____________, ___________, or ___________factors. 6. List symptoms of undiagnosed diabetes. 7. Diabetes is managed by maintaining _________________. 8. Long term complications of diabetes may include: 9. Hypoglycemia can be defined as: 10. Symptoms of hypoglycemia include: 11. Severe hypoglycemia can lead to ___________________ and can be reversed with a ______________ injection. 12. Hyperglycemia can be defined as: 13. Symptoms of hyperglycemia include: 14. Severe hyperglycemia can lead to _________________. 15. Diabetes is the leading cause of ________________ and __________________. 16. Individuals developing antibodies to pancreatic cells can be treated with small doses of ______________ as a preventative measure. 17. Other treatment methods being researched are: Activity #2 Complete the matching and short-answer activity. 1. In the following columns, match the hormone on the left with its source on the right. _____ thyroxine a. hypothalamus _____ estrogen b. adrenals _____ thyroid-stimulating hormone c. adrenal medulla _____ insulin d. pituitary gland _____ antidiuretic hormone e. ovary _____ aldosterone f. thyroid gland _____ catecholamines (epi. and norepi.) g. pancreas 2. List the target tissue and specific action of each hormone listed. Thyroxine: Aldosterone: Human Growth Hormone: Prolactin: Thyroid Stimulating Hormone (TSH): Insulin: Parathyroid Hormone (PTH): Catecholamines (epinephrine, norepinephrine): Cortisol: Activity #3 Complete the following case-studies.
    [Show full text]
  • Anatomy of Endocrine System
    Anatomy of Endocrine system Introduction, Pituitary gland and Thyroid gland Prepared by Dr. Payal Jain Endocrine System I. Introduction A. Considered to be part of animals communication system 1. Nervous system uses physical structures for communication 2. Endocrine system uses body fluids to transport messages (hormones) II. Hormones A. Classically, hormones are defined as chemical substances produced by ductless glands and secreted into the blood supply to affect a tissue distant from the gland, but now it is understood that hormones can be produced by single cells as well. 1. epicrine a. hormones pass through gap junctions of adjacent cells without entering extracellular fluid 2. paracrine a. hormones diffuse through interstitial fluid (e.g. prostaglandins) 3. endocrine a. hormones are delivered via the bloodstream (e.g. growth hormone Different endocrine glands with cell Organ Division arrangement Cell arrangement/morphology Hormone Hypophysis Adenohypophysis Pars distalis Cells in cords around large-bore capillaries: Acidophils Growth hormone, prolactin Basophils ACTH, TSH, FSH, LH Pars intermedia Mostly basophilic cells around ACTH, POMC cystic cavities Pars tuberalis Narrow sleeve of basophilc cells LH around infundibulum Neurohypophysis Pars nervosa Nerve fibers and supporting cells Oxytocin and (pituicytes) vasopressin (produced in hypothalamus) Infundibulum Nerve fibers (traveling from hypothalamus to pars nervosa) Pancreas Islet of Langerhans Irregularly arranged cells with Insulin, glucagon many capillaries Follicles: Simple
    [Show full text]
  • AP Biology--ENDOCRINE SYSTEM OUTLINE
    THE ENDOCRINE SYSTEM – PRELIM ACTIVITY HORMONES AT LARGE- Guy meets Gal and the rest is ....Hormonal???? WHAT DO YOU THINK THEY ARE SAYING/DOING? WHAT DOES THIS SYMBOL MEAN TO YOU? WHAT DOES THIS SYMBOL MEAN TO YOU? WHAT DOES THIS SYMBOL MEAN TO YOU? WHAT DOES THIS SYMBOL MEAN TO YOU? WHAT DOES THIS SYMBOL MEAN TO YOU? WHAT DOES THIS SYMBOL MEAN TO YOU? 1 THE ENDOCRINE SYSTEM A. The Endocrine system is one of the body's main systems for communicating, controlling, and regulating the body's needs and functions through chemical messages and signals called HORMONES . These hormones are produced by a system of glands located throughout our body. They are crucial in the regulating process of the entire body, yet comprise less than 3 pounds of our body weight. GLANDS OF THE ENDOCRINE SYSTEM B. Roll of Hormones – Hormones travel throughout the body coordinating complex processes like growth, metabolism, fertility, the immune system, behavior, birthing, development, growth proportioning of the body’’s regions and limbs, stimulate and guide puberty, digestion and many more functions. C. GLANDS IN THE BRAIN 2 1. HYPOTHALAMUS GLANDLies above the pituitary gland. It controls all means of production and allows the hormones to start and stop in the pituitary glands, through "releasing hormones” such as: 1. Growth hormones (GH), 2. Thyrotroph, 3. Thyrotropin-releasing hormone (TRH), 4. Corticoptropin (CHR), Gonadotropin (GnRH), 5. Lutenizing hormone (LH), 6. Follicle-stimulating hormone (FSH). 2. PITUITARY GLAND Known as the "master gland" because its hormones regulate so many functions. However, it obeys the commands of the hypothalamus gland.
    [Show full text]