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StuDocu is not sponsored or endorsed by any college or universitySummary of the Endocrine SystemAnatomy and Physiology (Technische Universiteit Delft)StuDocu is not sponsored or endorsed by any college or universitySummary of the Endocrine SystemAnatomy and Physiology (Technische Universiteit Delft)Downloaded by Lauren Myburgh ([email protected])lOMoARcPSD|3704854
7; The Endocrine SystemChapter 16The endocrine system is one of the body’s two major control systemsFigure1:Locationofselecteden-docrine organs of the bodyThenervousandendocrinesystemsarethemajorcontrolling systems of the body.The nervous sys-tem exerts rapid controls via nerve impulses; the en-docrine system exerts are prolonged effects via hor-mones.Hormonal regulated processes includereproductiongrowth and developmentmaintaining electrolyte, water, and nutrient bal-anceregulating cellular metabolism and energy balanceand mobilizing body defensesThere are two kinds of glands:Exocrine glandsproducenon-hormonalsub-stances, such as sweat and saliva, and have ductsthat carry these substances to a membrane sur-face.Endocrine glands, also calledductless glands,produce hormones and lack ducts. Typically well-vascularized glands that release hormones directly into the blood or lymph. They are smalland widely separated in the body.The purely endocrine organs are the pituitary, thyroid, parathyroid, adrenal, and pineal gland.The hypothalamus is aneuroendocrine organ. The pancreas, gonads, and placenta also haveendocrine tissue.Local chemical messengers, not generally considered part of the endocrine system, include au-tocrines, which act on the cells that secrete them, and paracrines, which act on a different celltype nearby.Hormones act through second messengers or by activating specific genesHormones alter cell activity by stimulating or inhibiting characteristic cellular processes of theirtarget cells.Cell responses to hormone stimulation may produce one or more of the following changes:Change of plasma membrane permeability or membrane potential.Stimulates synthesis of enzymes and other proteins within the cell.Activates, or deactivates enzymes.Induces secretory activity.Stimulates mitosis.1Downloaded by Lauren Myburgh ([email protected])lOMoARcPSD|3704854
Second-messenger mechanisms employing G proteins and intracellular second messengers area common means by which amino acid-based hormones interact with their target cells. In thecyclic AMP system, the hormone binds to a plasma membrane receptor that couples to a Gprotein. When the G protein is activated, it couples to adenylate cyclase, which catalyzes thesynthesis of cyclic AMP form ATP. Cyclic AMP initiates reactions that activate protein ki-nases and other enzymes, leading to cellular responses. The PIP2-calcium signaling mechanismis another important second-messenger system. Other second messengers are cyclic GMP andcalcium.(water-soluble hormones)Steroid hormones (and thyroid hormone) enter their target cells and effect responses byactivating DNA, which initiates messenger RNA formation leading to protein synthesis.(Lipid-

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Term
Spring
Professor
BJ Page
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Endocrine System, Lauren Myburgh

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