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Published byHilda Chandler Modified over 9 years ago
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1 The Endocrine System
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2 Endocrine system – the body’s second great controlling system Nervous and Endocrine Regulation Delivery Control Response Duration
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3 Review of glands Exocrine Endocrine – pituitary, thyroid, parathyroid, adrenal, pineal, thymus, ovaries, testes, pancreas, hypothalamus
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4 Hormones Hormones Regulate the metabolic function of other cells Are classified as: Amino acid-based hormones Steroids Eicosanoids Target Cell
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5 How hormones activate cells: Amino acid based (amine) – Amines, thyroxine, peptide, and protein hormones Second messenger mechanism
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6 Amino acid (Amine) based 1)Hormone binds 2)The G protein is then activated 3)Activated G protein activates the effector enzyme adenylate cyclase 4)Adenylate cyclase generates cAMP from ATP 5)cAMP activates protein kinases (chemical reactions)
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7 Steroid based gonadal and adrenocortical hormones, How hormones work
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8 Hormone Mode of Action Changes in target cells Alter plasma membrane permeability Stimulate protein synthesis Activate or deactivate enzyme systems Induce secretory activity Stimulate mitosis Hormone inactivation and removal
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9 Target cell receptor specificity Hormones affect target cells only. Bind to cell surface or intracellular protein receptors. Further activation is dependent on 3 other factors: 1)Blood levels 2)Relative number of receptors 3)Affinity of those receptors a)Up-regulation b)Down-regulation
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10 Three types of hormone interaction Permissiveness Synergism Antagonism Interactions of Hormones at Target Cells
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11 Stimuli – Control of hormone release 1) Humoral 2) Neural 3) Hormonal
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12Questions: 17.2 Which system produces a quicker response, the nervous system or the endocrine system? Which system produces a longer-acting response? 17.4 Why would follicle stimulating hormone act on the ovaries but not on the thyroid? 17.6 Where do lipid-soluble hormones bind to their target cells? Where do water soluble hormones bind to their target cells? 17.7 Why is cyclic AMP considered to be a second messenger? 17.8 What factors determine the responsiveness of a target cell to a hormone? 17.9 What are the three influences over hormone secretion? Why are organs such as the kidneys, stomach, heart, and skin considered to be part of the endocrine system?
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