Psychology
The Function of the Endocrine System - Glands and hormones
The endocrine system is a network of glands that produce and release hormones, which regulate various bodily functions such as metabolism, growth, and mood. Glands like the pituitary, thyroid, and adrenal glands secrete specific hormones that travel through the bloodstream to target organs, where they exert their effects. This system plays a crucial role in maintaining homeostasis and responding to stress.
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eBook - PDFFundamentals of Children's Anatomy and Physiology
A Textbook for Nursing and Healthcare Students
- Ian Peate, Elizabeth Gormley-Fleming(Authors)
- 2014(Publication Date)
- Wiley-Blackwell(Publisher)
Learning outcomes 234 Chapter 11 The endocrine system Introduction There are two regulatory systems within the body that are responsible for the transmission of vital messages and the integration of bodily functions: the nervous and endocrine systems. The nervous system works by sending electrical impulses via neurones and neurotransmitters to transfer signals across synapses. The endocrine system comprises a collection of glands (Figure 11.1) that secrete a range of different types of hormones directly into the bloodstream which then transports that hormone to take effect in more distant target organs or tissues (Molina, 2013). The unique features of these glands are that they are ductless in nature, have a high vascularity and store their hormones within granules (Rogers, 2012). In contrast, exocrine glands (such as sweat glands, the gall bladder and salivary glands) secrete their hormones using hollow lumen ducts and are less vascular. Endocrine glands are controlled directly by stimulation from the nervous system, as well as by chemical receptors in the blood and hormones produced by other glands (Waugh and Grant, 2010). By regulating the functions of organs in the body, these glands help to maintain the body’s homeostasis. Growth and development, sexual development and control of many internal body functions, such as glucose and mineral regulation as well as the stress response are among the many essential physiological processes regulated by the actions of hormones. The anatomy of the endocrine system can be seen in Figure 11.1. The integrity and health of the endocrine system is essential to maintaining healthy body weight, growth and both physical and emotional development. The endocrine system signifi- cantly affects children and teenagers who are experiencing a high rate of development, but different parts of this system play a role as ageing occurs.
eBook - PDF- Ann Scott, Elizabeth Fong(Authors)
- 2018(Publication Date)
- Cengage Learning EMEA(Publisher)
Function of the Endocrine System Our bodies need to coordinate and integrate all of their functions into one harmonious whole, homeosta- sis. The maintenance of homeostasis involves growth, maturation, reproduction, and metabolism. Human behavior is shaped by the endocrine system and the nervous system working in a unique partnership. The hypothalamus of the brain (nervous system) sends directions via chemical signals (neurohormones) to the pituitary (endocrine system). The secretions of the pituitary gland then send chemical signals or mes- sengers in the form of hormones, stimulating other endocrine glands to secrete their unique hormones. The hormones thus produced coordinate and direct the activities of target cells and target organs. The major glands of the endocrine system include pituitary, pineal, thyroid, parathyroid, thy- mus, adrenal, pancreas, and the gonads (ovaries in the female and testes in the male). Figure 11-2 (A) Exocrine gland; (B) endocrine gland Body surface Gland cell Secretion A. Exocrine gland (has duct) Gland cell B. Endocrine gland (ductless) Hormone Bloodstream carries hormones to a target organ Duct carries chemicals to a target site Copyright 201 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 212 CHAPTER 11 Endocrine System depression in the sphenoid bone of the skull (Figure 11-3). The pituitary gland is connected to the hypothalamus by a stalk called the infundibulum. The pituitary gland is divided into an anterior lobe and a posterior lobe (Figure 11-4).
eBook - PDF- George Spilich(Author)
- 2023(Publication Date)
- Wiley(Publisher)
Com- plete the worksheet Fast- and Slow-Response Systems. GK Hart/Vikki Hart/Stone/Getty Images 204 C H A P T E R 8 The Endocrine System Hormones The secretions of the endocrine glands are hormones. Hormones are chem- ical messengers that travel through the blood to effect a change in either physiology or behav- ior. Hormones affect covert behaviors such as homeostasis and metabolism, as well as overt behaviors such as wakefulness, sexual behavior, and mood swings. Although neurons and endocrine glands both carry information, they do so in very dif- ferent ways. Neurons employ neurotransmitters to carry a signal, whereas an endocrine gland uses a hormone for that same purpose. Neurons transfer that signal across a specific synapse and therefore have a very localized effect, whereas glands secrete a hormone into the blood- stream where it can travel throughout the body, generating a global effect. As hormones are carried through the body, they signal target cells to alter their function; for example, a hormone may affect growth, activity level, or even the function of the target cell. Just as synapses have receptors specific to each neurotransmitter, there are receptors specific Pineal gland Trachea Hypothalamus Pituitary gland Thyroid gland Trachea Thymus Heart Stomach Kidney Uterus Ovary Testes Thyroid gland Male Female Small intestine Pancreas Parathyroid glands (behind thyroid glands) FIGURE 8.2 The endocrine glands The hypothalamus, the pituitary, and the pineal gland are the part of the endocrine system that is located in the brain. The thyroid and parathyroid glands, thymus, adrenal glands, pancreas, and gonads are located outside the brain. The endocrine glands regulate a wide range of metabolic and behavioral functions. 8.1 An Introduction to the Endocrine System 205 to each hormone produced by the endocrine system.
eBook - PDF- Bryan H. Derrickson(Author)
- 2019(Publication Date)
- Wiley(Publisher)
At the same time or a little later, increasing levels of testosterone in males begin to help build muscle mass and enlarge the vocal cords, producing a lower-pitched voice. These changes are just a few examples of the powerful influence of endocrine secretions. Less dramatically, perhaps, multitudes of hormones help maintain homeostasis on a daily basis. They regulate the activity of smooth muscle, cardiac muscle, and some glands; alter metabolism; spur growth and development; influence reproductive processes; and participate in circadian (daily) rhythms established by the suprachiasmatic nucleus of the hypothalamus. In this chapter, you will learn about the major hormone-producing glands and tissues that comprise the endocrine system. You will also examine how hormones govern body activities. In addition, you will have several opportunities to see how the nervous and endocrine systems function together as an interlocking “supersystem.” For example, certain parts of the nervous system stimulate or inhibit the release of hormones by the endocrine system. Pituitary gland Hypothalamus Pineal gland Skin Liver Adrenal Gland Small Intestine Pancreas Thyroid gland Thymus Heart Stomach Kidney Parathyroid glands (behind thyroid gland) Ovary (in females) Testes FIGURE 13.1 Components of the endocrine system. Question What is a hormone? The endocrine system consists of all glands, organs, and tissues that contain hormone-secreting cells. 13.1 Overview of the Endocrine System 449 phenomenon, known as up-regulation, makes a target cell more sensitive to a hormone (Figure 13.3b). The mechanisms for down-regulation and up-regulation were discussed in Chapter 6 (see Section 6.3). Hormones Are Chemically Classified as Lipid-Soluble or Water-Soluble Hormones can be divided into two broad chemical classes: those that are lipid-soluble (hydrophobic) and those that are water- soluble (hydrophilic).
eBook - PDF- Cecie Starr, Beverly McMillan(Authors)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Reproductive system The hypothalamus regulates the release of sex hormones that govern the development and functioning of ovaries and testes (the gonads). Oxytocin triggers uterine muscle contractions during labor and (with prolactin) for milk release for a nursing infant. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) also have key roles in reproduction. Digestive system Insulin and GH support the delivery of nutrients to all cells by stimulating cells to take up glucose from the bloodstream. The Endocrine System The endocrine system produces hormones, signaling molecules that travel in the bloodstream to nearly all body cells. Each kind of hormone influences the activity of its target cells. Along with signals of the nervous system, these changes adjust body functions in ways that maintain homeostasis in the body as whole. In general, responses to hormones take longer and last longer than responses to nerve impulses. Hormones govern long-term events such as bodily growth and metabolism. The Endocrine System in Homeostasis Skeletal system Growth hormone stimulates the growth of bones. Parathyroid hormone (PTH) is the main regulator of blood calcium levels. Calcitonin stimulates uptake of calcium from blood as needed to form bone tissue. Nervous system Epinephrine supports the sympathetic nervous system in the fight–flight response and helps the CNS regulate blood pressure. Hormones that regulate blood sugar ensure adequate fuel for brain cells. Urinary system Aldosterone and ANP support the urinary system’s management of salt–water balance by promoting or reducing the reabsorption of sodium. Muscular system Growth hormone stimulates development of skeletal muscle mass.
- Gerard J. Tortora, Bryan H. Derrickson, Brendan Burkett, Gregory Peoples, Danielle Dye, Julie Cooke, Tara Diversi, Mark McKean, Simon Summers, Flavia Di Pietro, Alex Engel, Michael Macartney, Hayley Green(Authors)
- 2021(Publication Date)
- Wiley(Publisher)
CHAPTER 18 The endocrine system LEARNING OBJECTIVES After studying this chapter, you should be able to: 18.1 compare control of body functions by the nervous system and endocrine system 18.2 distinguish between exocrine and endocrine glands 18.3 compare the classes of hormones and describe how they interact with target-cell receptors 18.4 describe the two general mechanisms of hormone action 18.5 describe the mechanisms of control of hormone secretion 18.6 describe the properties of the hypothalamus and pituitary gland, and the relationships between them 18.7 describe the location, histology, hormones, and functions of the thyroid gland 18.8 describe the location, histology, hormone, and functions of the parathyroid glands 18.9 describe the location, histology, hormones, and functions of the adrenal glands 18.10 describe the location, histology, hormones, and functions of the pancreatic islets 18.11 describe the location, hormones, and functions of the male and female gonads 18.12 describe the properties of the pineal gland and its secretions 18.13 describe the hormonal properties of cells in tissues and organs that are not traditionally considered endocrine glands 18.14 describe how the body responds to stress 18.15 describe the development of endocrine glands 18.16 describe the effects of ageing on the endocrine system. OPENING CASE The impact of COVID-19 on the endocrine system The endocrine system is a complex relationship of anatom- ical structures and physiological processes underpinning the body’s ability to communicate within and between sys- tems. As an intricate network of neuro-hormonal signalling, the body’s homeostasis relies heavily on the feedforward and feedback nature of the hormones travelling throughout the circulation. Disturbance of any of the pathways can ultimately result in acute and chronic pathophysiological conditions and impact on life expectancy.
No longer available |Learn more- Ann Scott, Elizabeth Fong(Authors)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
The exact nature and function of the prostaglandins are being extensively studied by scientists. A host of hormones are produced throughout the body. They can originate from many different glands or other organs. A complete description of all the hormones in the body is beyond the intent of this anatomy textbook. Neurohormones Neurohormones (new-roh-HOR-mohnz) are pro- duced and released by the neurons in the brain rather than the endocrine glands and delivered to organs and tissue through the bloodstream An example is neuro- hormones secreted by the hypothalamus that influence the secretion of the pituitary. Leptin Leptin (LEP-tin) is secreted by the fat cells in adipose tissue. Leptin travels via the bloodstream to the hypo- thalamus appetite center where it acts on the hypo- thalamus to suppress appetite and burn fat stored in adipose tissue. Ghrelin Ghrelin (GRE-lin) is produced by the stomach and is an appetite stimulant. It appears to be the wake-up call to eat. Its level peaks just before mealtime and dimin- ishes after meals. Function of the Endocrine System Our bodies need to coordinate and integrate all of their functions into one harmonious whole, homeosta- sis. The maintenance of homeostasis involves growth, maturation, reproduction, and metabolism. Human behavior is shaped by the endocrine system and the nervous system working in a unique partnership. The hypothalamus of the brain (nervous system) sends directions via chemical signals (neurohormones) to the pituitary (endocrine system). The secretions of the pituitary gland then send chemical signals or mes- sengers in the form of hormones, stimulating other endocrine glands to secrete their unique hormones. The hormones thus produced coordinate and direct the activities of target cells and target organs. The major glands of the endocrine system include pituitary, pineal, thyroid, parathyroid, thy- mus, adrenal, pancreas, and the gonads (ovaries in the female and testes in the male).
eBook - ePub- Ruth Hull(Author)
- 2021(Publication Date)
- Lotus Publishing(Publisher)
7 The Endocrine System IntroductionWhy is it that some people are exceptionally tall while others are small? Or some people can have children while others can’t? What is it that controls such processes in our bodies? It is the same system that controls our blood pressure, immune system, metabolism and even our response to danger. It is the endocrine system.The study of the glands and hormones of the endocrine system is endocrinology . In this chapter you will learn about the endocrine system and discover how it works together with your nervous system to control all the other systems of your body.Student objectives By the end of this chapter you will be able to:• Describe the functions of the endocrine system• Describe the organisation of the endocrine system• Explain what a hormone is and how it works• Identify the differences between the nervous and endocrine systems• Describe the endocrine glands and the hormones they produce• Identify the common pathologies of the endocrine system.Did you know?Before looking at the functions of the endocrine system, it helps to understand exactly what endocrine glands and hormones are. There are two types of glands in the body: exocrine and endocrine.The endocrine glands are not the only tissues in the body that secrete hormones. The kidneys, stomach, liver, small intestine, skin, heart and placenta also contain cells that secrete small amounts of hormones.• Exocrine glands: These secrete substances into ducts that carry the substances into body cavities or to the outer surface of the body. Examples of exocrine glands include sudoriferous (sweat), sebaceous (oil), mucous and digestive glands.• Endocrine glands: These secrete substances into the extracellular space around their cells. The secretions then diffuse into blood capillaries and are transported by the blood to target cells located throughout the body. Substances secreted by endocrine glands are called hormones
eBook - PDF- Gerard J. Tortora, Bryan H. Derrickson(Authors)
- 2020(Publication Date)
- Wiley(Publisher)
The nervous and endocrine systems act together to coordinate functions of all body systems. Recall that the nervous system acts through nerve impulses conducted along axons of neu- rons. At synapses, nerve impulses trigger the release of medi- ator (messenger) molecules called neurotransmitters (shown in Figure 12.23). The endocrine system also controls body activi- ties by releasing mediators, called hormones, but the means of control of the two systems are very different. A hormone (hormo = to excite or get moving) is a mole- cule that is released in one part of the body but regulates the activity of cells in other parts of the body. Most hormones enter interstitial fluid and then the bloodstream. The circulating blood delivers hormones to cells throughout the body. Both neurotransmitters and hormones exert their effects by binding to receptors on or in their “target” cells. Several chemicals act as both neurotransmitters and hormones. One familiar exam- ple is norepinephrine, which is released as a neurotransmitter by sympathetic postganglionic neurons and as a hormone by chromaffin cells of the suprarenal medullae. Responses of the endocrine system often are slower than responses of the nervous system; although some hormones act within seconds, most take several minutes or more to cause a response. The effects of nervous system activation are gen- erally briefer than those of the endocrine system. The nervous system acts on specific muscles and glands. The influence of the endocrine system is much broader; it helps regulate virtu- ally all types of body cells. We will also have several opportunities to see how the ner- vous and endocrine systems function together as an interlocking “supersystem.” For example, certain parts of the nervous sys- tem stimulate or inhibit the release of hormones by the endo- crine system. Table 18.1 compares the characteristics of the nervous and endocrine systems.
eBook - PDF- James McCubbin(Author)
- 2012(Publication Date)
- Academic Press(Publisher)
II Endocrine Regulation This page intentionally left blank 9 Stress, the Hypothalamic—Pituitary-Adrenal Axis, and Depression I. Introduction II. CRF and the Stress Response III. CRF and Depression IV. Summary References Control of the hypothalamic-pituitary-adrenal (ΗΡΑ) axis is a multistep integrated process involving several central nervous system sites (cerebral cortex, amygdala, locus ceruleus, hippocampus, etc.). Most, but perhaps not all, of these central inputs are eventually channeled to the hypothala-mus. In the hypothalamus these signals are transduced to humoral-type messages, release and release-inhibiting hormones, that are then released from nerve terminals in the eminence, the site of the primary plexus of the hypothalamo—hypophyseal-portal system. These hypothalamic hypophysi-otrophic hormones released from the hypothalamus travel a short distance to the anterior pituitary, where the signal is amplified and converted by the release of pituitary trophic hormones. The adrenohypophyseal hormones are then released into the general circulation, travel to their appropriate target organs, and effect a multitude of specific organ system responses. These responses are known to have major influences on blood pressure reg-ulation, reproductive function, and energy mobilization. In addition to the central control mentioned above, the various neuroendocrine axes are also influenced by a variety of feedback control loops. These feedback con-Stress, Neuropeptides, and Systemic Disease Copyright © 1991 by Academic Press, Inc. All rights of reproduction in any form reserved. James C. Ritchie Departments of Psychiatry and Pharmacology Duke University Medical Center Durham, North Carolina Charles B. Nemeroff Departments of Psychiatry and Pharmacology Duke University Medical Center Durham, North Carolina I. Introduction 181 182 James C. Ritchie and Charles B. Nemeroff trols can be of both a fast and slow nature and are known to involve both central and peripheral sites.
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