rav65819_ch46_919-942

rav65819_ch46_919-942 - ; 46 chapter The Endocrine System...

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;;;;;;;;;; 46 chapter The Endocrine System introduction DIABETES IS A DISEASE IN WHICH well-fed patients appear to starve to death. The disease was known to Roman and Greek physicians, who described a “melting away of flesh” coupled with excessive urine production “like the opening of aqueducts.”
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Until 1922, the diagnosis of diabetes in children was effectively a death sentence. In that year, Frederick Banting and Charles Best extracted the molecule insulin from the pancreas. Injections of insulin into the bloodstream dramatically reversed the symptoms of the disease. This served as an impressive confirmation of a new concept: that certain internal organs produced powerful regulatory chemicals that were distributed via the blood. We now know that the tissues and organs of the vertebrate body cooperate to maintain homeostasis through the actions of many regulatory mechanisms. Two systems, however, are devoted exclusively to the regulation of the body organs: the nervous system and the endocrine system. Both release regulatory molecules that control the body organs by binding to receptor proteins on or in the cells of those organs. In this chapter, we examine the regulatory molecules of the endocrine system, the cells and glands that produce them, and how they function to regulate the body’s activities. concept outline 46.1 Regulation of Body Processes by Chemical Messengers Some neurotransmitters also act as circulating hormones Endocrine glands produce three chemical classes of hormones Hormones can be categorized as lipophilic or hydrophilic Paracrine regulators exert powerful effects within tissues 46.2 Actions of Lipophilic Versus Hydrophilic Hormones
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Lipophilic hormones activate intracellular receptors Hydrophilic hormones activate receptors on target cell membranes 46.3 The Pituitary and Hypothalamus: The Body’s Control Centers The pituitary is a compound endocrine gland The posterior pituitary stores and releases two neurohormones The anterior pituitary produces seven hormones Hypothalamic neurohormones regulate the anterior pituitary Feedback from peripheral endocrine glands regulates anterior pituitary hormones Hormones of the anterior pituitary work directly and indirectly 46.4 The Major Peripheral Endocrine Glands The thyroid gland regulates basal metabolism and development Calcium homeostasis is regulated by several hormones The adrenal gland releases both catecholamine and steroid hormones Pancreatic hormones are primary regulators of carbohydrate metabolism 46.5 Other Hormones and Their Effects Sex steroids regulate reproductive development Melatonin is crucial to circadian cycles Some hormones are not produced by endocrine glands Insect hormones control molting and metamorphosis Cancer cells may alter hormone production or have altered hormonal responses 919 rav65819_ch46_919-942.indd 919 rav65819_ch46_919-942.indd 919 12/6/06 4:38:11 PM 12/6/06 4:38:11 PM 46.1 Regulation of Body Processes by Chemical Messengers
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This note was uploaded on 10/15/2010 for the course BIO BIO1 taught by Professor Lipke during the Fall '09 term at CUNY Brooklyn.

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rav65819_ch46_919-942 - ; 46 chapter The Endocrine System...

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