endocrine.pdf - Endocrine and Neuroendocrine Physiology Ch...

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Endocrine and Neuroendocrine PhysiologyCh. 16 Hill et al. 2012Ch. 3 Moyes et al. 2008
Outline of Lecture 81.Intro to Hormones endocrine organs, tissues, and cells2.Classes of Hormones3.Hormone Receptors4.Cell Signaling and Feedback Regulation5.The Pituitary and Adrenal Glands6.The Vertebrate Stress ResponseNEXT LECTURENutrient metabolism (pancreas, insulin, glucagon, diabetes)Hormonal Regulation of Salt and Water Balance (vasopressin, aldosterone, ANP)Endocrine Control of Calcium Metabolism (PTH, vitamin D, calcitonin)Growth HormoneThyroid Hormone
ENDOCRINE SYSTEM the second control systemductless endocrine glands – release hormones into capillaries (e.g., thyroid gland, or adrenal glands in higher vertebrates) isolated cells or clusters of endocrine cells(e.g., cells of digestive system; in fish and amphibians, the equivalent of adrenal glands are a group of cells intermingled with kidney tissue called interrenal tissue)Endocrine gland typesdiscretediffuseintermediate
Neuronal and hormonal signaling both convey information over long distancesBothwidespreadslowspecificneuralepithelial
Fig. 16.1 Hill et al. 2012- neurotransmitters- hormones
HormonesReleased by nonneural endocrine cells or neuronsExert regulatory influences on the function of target cellsTravel through bloodstreamEffective at low concentrations(because of receptor specificity)Secretory cells may be organized into discrete organs (endocrine glands) or isolated clusters of cells
Blood Concentration of HormoneA function of:Rate of addition(secretion)Rate of removal (metabolic destruction or excretion)Peripheral activation (conversion to active form)Half-life = time required to reduce concentrations by ½rate of removal from blood is constant for a molecule(enzymatically degraded at target or by liver and kidneys)
1.Steroid Hormones2.Peptide & Protein Hormones3.Amine HormonesClasses of Hormones
1. Steroid hormones are synthesized from cholesterolFig. 16.2 Hill et al. 2012AldosteroneCortisolTestosterone (androgen)Estradiol (estrogen)PregnenoloneCholesterolSecreted from gonads, adrenal glands, skin, and placentaInsect molting hormones are also steriods (ecdysone)Lipid soluble – can pass through cell membranes to reach nuclear receptors (hydrophobic)Synthesized on demandadrenal glands - mitochondriadiet or by synthesis in the liver and steroidogenic endocrine cellsSER
consist of assemblages of amino acidsVary in size 3 AA (TRH) up to 200 AA (GH)Soluble in aqueous solutions (hydrophilic), thus do not cross cell membranes

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