Endocrine System

Endocrine System - 1 1 Human Anatomy First Edition...

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Unformatted text preview: 1 1 Human Anatomy, First Edition McKinley & O'Loughlin Chapter 20 Lecture Outline: Endocrine System 20-2 Endocrine System ¡ Endocrine system and the nervous system often work together to bring about homeostasis. ¡ Both use specific communication methods and affect specific target organs. ¡ Their methods and effects differ. 3 2 20-4 Endocrine Glands & Hormones ¡ Exocrine glands ¡ secretions released into ducts opening onto an epithelial surface ¡ Endocrine glands ¡ ductless organs that secrete their molecules directly into the bloodstream ¡ All endocrine cells are located within highly vascularized areas to ensure that their products enter the bloodstream immediately. 20-5 Overview of Hormones ¡ Molecules that have an effect on specific organs. ¡ Only cells with specific receptors for the hormone respond to that hormone. ¡ Called target cells , and the organs that contain them are called target organs. ¡ Organs, tissues, or cells lacking the specific receptor do not respond to its stimulating effects. 20-6 Classification of Hormones ¡ Peptide hormones ¡ formed from chains of amino acids ¡ most of our body’s hormones are peptide hormones ¡ longer chains are called protein hormones ¡ example is growth hormone ¡ Steroid hormones ¡ type of lipid derived from c holesterol ¡ example is testosterone ¡ Biogenic amines ¡ small molecules produced by altering the structure of a specific amino acid ¡ example is thyroid hormone 3 20-7 Negative Feedback Loop ¡ A stimulus starts a process, and eventually either the hormone that is secreted or a product of its effects causes the process to slow down or turn off. ¡ Many hormonal systems work by negative feedback mechanisms. ¡ one example is the regulation of the blood glucose level in the body 8 20-9 Positive Feedback Loop ¡ Accelerates the original process, either to ensure that the pathway continues to run or to speed up its activities. ¡ Only a few positive feedback loops occur in the human endocrine system. ¡ one example is the process of milk release from the mammary glands 4 10 20-11 Hypothalamic Control of the Endocrine System ¡ As the master control center of the endocrine system the hypothalamus oversees most endocrine activity....
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Endocrine System - 1 1 Human Anatomy First Edition...

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