How the Endocrine System affects Chronic Disease

How the Endocrine System affects Chronic Disease ORDER NOW FOR CUSTOMIZED AND ORIGINAL ESSAY PAPERS ON How the Endocrine System affects Chronic Disease Choose one of the CDC’s five most common chronic diseases (heart disease, stroke, cancer, diabetes, or arthritis) and describe the anatomical and physiological changes associated with the endocrine system. Describe normal function of the system and how the disease alters the normal function. List signs and symptoms that indicate the disease has developed, specific to the system being covered. Identify and describe steps people can take to reduce their risk of developing the chronic disease. How the Endocrine System affects Chronic Disease Use two scholarly sources to support your initial post. All sources must be referenced and cited according to APA guidelines Initial post should be 250 words at a minimum. attachment_1 10 The Endocrine System The Body’s Other Control Center Here we are again, talking about control. We have already visited one of the control systems—the complex structure of cells and connections known as the nervous system. Now we visit yet another control system—the endocrine system. These two control systems may seem like separate systems, but they are interconnected and always monitor each other’s activities. The nervous system collects information and sends orders with a speed that is truly mind-boggling. Whereas the endocrine system also collects information and sends orders, it’s a slower, more subtle control system. The endocrine system’s orders to the body also last much longer than those made by the nervous system. You might think of the endocrine system as sending “standing orders,” or orders meant to be obeyed inde initely unless changed by another set of orders. The orders change subtly on a regular basis, but their intention is constant. The nervous system, on the other hand, issues orders that are to be obeyed instantaneously but are used for short-term situations. The endocrine system demands organs to “carry on,” whereas the nervous system expects them to respond immediately. On our journey, suppose we stop at an amusement park to ride a roller coaster. Afterward, en route to our next destination, we are forced off the road because of a near miss with a truck. Even after the roller coaster ride is over or the truck is long gone, your legs still shake, your heart continues to race, and your blood pressure remains elevated, even though you are no longer in danger. We call such lingering effects the “adrenaline rush.” These lingering effects are not due to continued activity of the nervous system, but rather to endocrine activity deliberately triggered by the autonomic nervous system. LEARNING OUTCOMES At the completion of your journey through this chapter, you will be able to: ? Discuss the functions of the various endocrine glands ? Describe the purpose and effects of hormones within the body ? Discuss the process of homeostatic control and feedback mechanisms of hormone levels ? Differentiate between hormonal control, humoral control, and neural control of hormones ? Explain common diseases of the endocrine system Pronunciation Guide Correct pronunciation is important in any journey so that you and others are completely understood. Here is a “see and say” Pronunciation Guide for the more dif icult terms to pronounce in this chapter. In addition, the Audio Glossary includes an audio pronunciation and de inition of each of these terms. Please note that pronunciations given are referenced to medical dictionaries, and regional variations may exist. adrenal cortex (ah DREE nal KOR teks) adrenal medulla (ah DREE nal meh DULL lah) antidiuretic hormone (AN tye dye yoo RET ick) endocrine (EHN doh krin) epinephrine (EP ih NEFF rin)How the Endocrine System affects Chronic Disease homeostasis (HOH mee oh STAY sis) hormone (HOR moan) hypercholesterolemia (HIGH per koh LESS ter ohl EE me ah) hyperpituitarism (HIGH per peh TOO eh tair izm) hypopituitarism (HIGH poh peh TOO eh tair izm) hypothalamus (HIGH poh THAL ah mus) melatonin (MELL ah TOH nin) norepinephrine (nor EP ih NEFF rin) oxytocin (AHK see TOH sin) pancreas (PAN kree ass) parathyroid gland (PAIR ah THIGH royd) pineal gland (PIN ee al) pituitary (pih TOO ih tair ee) prolactin (proh LAK tin) testes (TESS teez) thymus (THIGH mus) thyroid (THIGH royd) 10.1 ORGANIZATION OF THE ENDOCRINE SYSTEM The endocrine system has many organs that secrete a variety of chemical substances. Let’s begin by looking at the basic organization of the system. Endocrine Organs The endocrine system (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss412) is a series of organs and ductless glands (see FIGURE 10-1 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec1#ch10 ig1) ) in your body that secrete chemical messengers called hormones (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss599) into your bloodstream. (Note that endo means “into,” and crine means “to secrete.”) In contrast, exocrine (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss455) glands and organs such as the pancreas and the sweat, salivary, and lacrimal glands produce secretions that must exit that particular gland through a duct. We have already discussed some of the endocrine glands, such as the hypothalamus, pituitary, and pineal glands, because they are part of the nervous system and provide a link between the two control systems. We will visit some of the other endocrine glands later when we journey through the urinary, reproductive, and digestive systems. Many endocrine glands, like the hypothalamus and pancreas, have multiple functions. It may seem like an overwhelming task to learn all the endocrine glands and their associated hormones. Therefore, we will begin our discussion with a concise overview to lay a foundation on which to build. As we journey through this chapter, these concepts are reinforced and expanded. For now, see TABLE 10-1 How the Endocrine System affects Chronic Disease (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec1#ch10tab1) , which lists the wide variety of functions of endocrine organs. Amazing Body Facts Lesser-Known Endocrine Glands Did you know that many organs, such as the heart, small intestine, kidneys, stomach, and placenta, can also secrete hormones and therefore have endocrine-like functions? These and many other organs are not listed as endocrine glands because their primary jobs are focused on other tasks, like pumping blood, storing and digesting food, or nourishing an embryo. But the hormones secreted by other organs are still an important part of the body’s control systems. Hormones The chemical messengers released by endocrine glands are called hormones (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss599) . We have already seen one type of chemical messenger: the neurotransmitter. Neurotransmitters are released by neurons at chemical synapses. They diffuse across the synapse (a very tiny space) to a cell on the other side, and they bind to that cell. They are cleaned up quickly, so their effects are localized and short-lived. Hormones, on the other hand, are released into the bloodstream and travel all over your body. Some hormones can affect millions of cells simultaneously. Their effects last for minutes or even hours or days. Many hormones are secreted constantly, and the amount secreted changes as needed. To help clarify the similarities and differences between a neurotransmitter and hormone, please see TABLE 10-2 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec1#ch10tab2) . FIGURE 10-1 ? The endocrine glands and their hormones. TABLE 10-1 ENDOCRINE ORGAN FUNCTIONS ENDOCRINE ORGAN HORMONE RELEASED EFFECT Hypothalamus A variety of hormones; see Table 10-3 Controls (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec3#ch10tab3) pituitary hormone levels Pineal Melatonin Believed to regulate sleep Pituitary A variety of hormones; see Table 10-3 Controls other (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec3#ch10tab3) endocrine organs Thyroid Parathyroid glands Thyroxine, triiodothyronine Controls cellular metabolism Calcitonin Decreases blood calcium Parathyroid hormone Increases blood calcium How the Endocrine System affects Chronic Disease ENDOCRINE ORGAN HORMONE RELEASED EFFECT Pancreas Insulin Lowers blood sugar Glucagon Raises blood sugar Epinephrine, norepinephrine Flight-or- ight response Adrenocorticosteroids Many different effects Ovaries Estrogen, progesterone Control sexual reproduction and secondary sexual characteristics, such as pubic hair and axillary hair Testes Testosterone Control secondary sexual characteristics, such as growth of beard and other hair, deepening of voice, increase in musculature, production of sperm Thymus Thymosin Immune system, causing maturation of white blood cells Adrenal glands TABLE 10-2 COMPARISON OF NEUROTRANSMITTERS AND HORMONES NEUROTRANSMITTERS HORMONES Chemical messengers Chemical messengers Bind to receiving cell Bind to receiving cell Control cell excitation Control cell activities Released by neurons Released by neurons, glands, or organs Released at chemical synapse Released into bloodstream Intended target very close Travel to distant target Effects happen quickly (less than a second) Effects take time (seconds or minutes) Effects wear off quickly (few seconds) Effects long lasting (minutes or hours) Affect single cell Can affect many cells How Hormones Work Like neurotransmitters, hormones work by binding to receptors on target cells. But hormones may bind not only to sites on the outside of the cell, like neurotransmitters, but also to sites inside the cell. If hormones bind to the outside of the cell, they can have several different effects, either changing cellular permeability or sending the target cell a message that changes enzyme activity inside the cell. Thus, the target cell changes what it has been doing, usually by making a new protein or turning off a protein it has been making. One special class of hormones, steroids (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss1289) , is particularly powerful because steroids can bind to sites inside cells. (Thyroid hormones also enter cells, but many other hormones do not.) Steroids are lipid molecules that can pass easily through the target cell membrane. These hormones can then interact directly with the cell’s DNA, the genetic material, to change cell activity. These hormones are carefully regulated by the body because of their ability, even in very small amounts, to control target cells. See the section “The Adrenal Glands” for further discussion of steroid hormones and the dangers of taking steroids. WEBSITE MEDIA EXTRA View a 3-D animation of the endocrine system and try an interactive drag-and-drop exercise. TEST YOUR KNOWLEDGE 10-1 Choose the best answer: 1. What chemical, when secreted into the bloodstream, controls the metabolic processes of target cells? a. neurotransmitter b. secretion c. hormoneHow the Endocrine System affects Chronic Disease d. ligand 2. Steroid hormones are very powerful because they: a. are hormones b. are medicine c. interact directly with DNA d. are secreted outside the body 3. Which of the following is true of hormones? a. They last a short time. b. They are fast acting. c. They affect distant targets. d. They leave the body. 10.2 CONTROL OF ENDOCRINE ACTIVITY Many endocrine glands and organs are active all the time. The amount of hormones they secrete changes as the situation demands, but unlike neurons, the cells in the endocrine glands often secrete hormones continuously. How is the activity controlled? How do these glands and organs know how much hormone to secrete? Homeostasis and Negative Feedback To understand how the endocrine system is controlled, we irst have to revisit the concept of homeostasis (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss595) discussed at the beginning of our journey in Chapter 1 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch01#ch01) (see FIGURE 10-2 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec2#ch10 ig2) ). Recall that many of the chemical and physical characteristics of the body have a standard level, or set point (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss1230) , that is the ideal level for that particular value. Blood pressure, blood oxygen, heart rate, and blood sugar, for example, all have “normal” ranges. Your control systems, nervous and endocrine, work to keep the levels at or near ideal. There is a way for your body to measure the variable, a place where the “ideal” level is stored, and a way for the body to correct levels that are not near ideal. For example, neurons measure your body temperature. The hypothalamus stores the set point. If your temperature falls below the set point temperature, the hypothalamus causes shivering to produce additional heat. If body temperature rises above the set point, the hypothalamus causes sweating. If any of the body’s dozens of homeostatic values become seriously disrupted, the control systems work to bring them back to set point. This process is called negative feedback (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss869) (see FIGURE 10-3 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec2#ch10 ig3) ). Most of you are familiar with negative feedback in real life. When you pump gas, a sensor in the nozzle turns off the low of gas when the tank is full. That is negative feedback. The gas is lowing, the tank is illing, and when the goal is reached, the gas stops lowing. In the body, negative feedback counteracts a change. As blood pressure rises, for example, your body works to bring it down to normal. If blood pressure falls, your body works to raise it back to the normal set point. Hormones work the same way. How the Endocrine System affects Chronic Disease As hormone levels rise, negative feedback turns off the endocrine organ that is secreting the hormone. The body is also capable of positive feedback (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss1059) , which increases the magnitude of a change. The low of sodium into a neuron during depolarization is a real-life example we have already visited. The more depolarized a neuron becomes, the more sodium lows in, so it becomes more depolarized, so more lows in, and so on. Childbirth also involves an important positive feedback mechanism (see the Clinical Application in this chapter). Therefore, positive feedback is not a way to regulate your body because it increases a change away from set point. What if instead of shivering when you got cold to raise your body temperature, you got colder and colder and colder? Sources of Control of Hormone Levels Hormone levels can be controlled by the nervous system (neural control (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss878) ), by other hormones (hormonal control (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss598) ), or by body luids such as the blood (humoral control (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss603) ). Neural Control FIGURE 10-2 ? Homeostasis is analogous to regulation of temperature via a thermostat. Some hormones are directly controlled by the nervous system. For example, the adrenal glands receive signals from the sympathetic nervous system. When the sympathetic nervous system is active (remember the near-wreck), it sends signals to the adrenal glands to release epinephrine and norepinephrine as hormones, prolonging the effects of sympathetic activity (see FIGURE 10-4 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec2#ch10 ig4) ). FIGURE 10-3 ? Homeostasis and negative feedback as related to control of body temperature. Hormonal Control FIGURE 10-4 ? Sympathetic control of adrenal gland. Other hormones are part of a hierarchy of hormonal control in which one gland is controlled by the release of hormones from another gland higher in the chain, which is controlled by another gland’s release of hormones yet higher in the chain. Orders are sent from one organ to another. This is very similar to a relay race at a track meet where the baton is smoothly handed from one runner to the next to send the baton to the inish line. Negative feedback controls the low of orders via hormones from one part of the “chain of command” to the other. For example, the hypothalamus has control over the pituitary, which has control over the adrenal gland, which secretes the hormone cortisol. Increased cortisol secretion is one way that the body copes with stress, and as cortisol levels rise in the blood, further release of hormones at the hypothalamus is depressed. This is an example of negative feedback. Please see FIGURE 10-5 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec2#ch10 ig5) . How the Endocrine System affects Chronic Disease Clinical Application CHILDBIRTH AND POSITIVE FEEDBACK Positive feedback is often harmful if the cycle cannot be broken, but sometimes positive feedback is necessary for a process to run to completion. A good example of necessary positive feedback is the continued contraction of the uterus during childbirth. When a baby is ready to be born, a signal tells the hypothalamus to release the hormone oxytocin (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss953) from the posterior pituitary. Oxytocin increases the intensity of uterine contractions. As the uterus contracts, the pressure inside the uterus caused by the baby moving down the birth canal increases the signal to the hypothalamus: More oxytocin is released, and the uterus contracts harder. As pressure gets higher inside the uterus, the hypothalamus is signaled to release more oxytocin, and the uterus contracts even harder. This cycle of ever-increasing uterine contractions due to ever-increasing release of oxytocin from the hypothalamus continues until the pressure inside the uterus decreases— that is, when the baby is born. FIGURE 10-5 ? Hormonal control of adrenal gland. CRH = corticotropin releasing hormone; ACTH = adrenocorticotropic hormone. Humoral Control Still other endocrine organs or glands can directly monitor the body’s internal environment by monitoring the body luids, such as the blood, and respond accordingly. Humoral pertains to body luids or substances, and therefore control through body luids is called humoral control (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss603) . For example, the pancreas secretes insulin in response to rising blood sugar, as shown in FIGURE 10-6 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec2#ch10 ig6) . In diabetics, like Maria, this response is impaired due to destruction of the pancreas by the immune system. FIGURE 10-6 ? Humoral control of blood sugar levels. TEST YOUR KNOWLEDGE 10-2 Choose the best answer: 1. Which of the following is the least common way that hormones are regulated? a. negative feedback b. chain of command c. positive feedback d. direct control by nervous system 2. The “ideal” value for a body characteristic is called the: a. set point b. average c. goal d. feedback point 3. _____________ feedback enhances a change in body chemistry. a. Negative b. Positive c. Regular d. Cyclic 10.3 THE MAJOR ENDOCRINE ORGANS The endocrine system has several organs, and each has speci ic tasks within the body. The messages to carry out these tasks are related to the hormones they release. The Hypothalamus We already visited the hypothalamus (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/bm01#gloss624) when we stopped at the central nervous system. Located in the diencephalon of the brain, this gland is an important link between the two control systems: nervous and endocrine (FIGURE 10-7 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch10lev1sec3#ch10 ig7) ). (Remember from Chapter 9 (http://content.thuzelearning.com/books/Colbert.3997.17.1/sections/ch09#ch09) , the diencephalon is situated between the brainstem and cerebrum and acts as an important regulator of many body processes.) The hypothalamus controls much of the body’s physiology, including hunger, thirst, luid balance, and body temperature, to name only a few of its functions. The hypothalamus is also, in part, the “commander-in-chief” of the endocrine system because it controls the pituitary gland and therefore most of the other glands in the endocrine system. TABLE 10-3 (http://content.thuzele … Get a 10 % discount on an order above $ 100 Use the following coupon code : NURSING10