Endocrine System

Endocrine System - Endocrine System Hormones ( I Hate...

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Endocrine System Hormones ( I Hate Chalk!)
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Hormones act on Target Cells Controlling rates of enzymatic reactions Controlling transport of ions or molecules across cell membranes Controlling gene expression and synthesis of proteins
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How do we know what we know? Hormone deficiency: remove suspected gland and observe animal for abnormalities Replacement therapy: put gland back or give extract to see what happens Hormone excess: implant gland in normal animal or give extract and observe Once gland identified: inject animal and observe response
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Definitions Hormone: chemical secreted by a cell or group of cells into the blood for transport to distant target Ectohormone: secreted into external environment Autocrine: influences the cell that releases the signal Paracrine: target cell is near signal releasing cell
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Classic Hormone Secretion
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Other Hormone Secretions Heart: secretes hormones that regulate sodium absorption in the kidney and water regulation Gastrointestinal tract ( stomach and intestines): secrete several hormones that regulate activity of GI tract, affect appetite regulation Kidneys and Gonads secrete hormones Skin: secretes or generates a precursor of a hormone ( under influence of ultraviolet light) vitamin D which is the precursor of a hormone converted by liver and kidney into active form During pregnancy the placenta which on the one hand exchanges nutrients and waste products between the mother and the fetus also secretes sex hormones Adipose tissue ( called Rodney Dangerfield of cells because get no respect) Now know that adipose tissues secrete hormones that regulate appetite, metabolism, insulin sensitivity
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Glands Discussed in Lecture Pineal gland – supposed to be associated with sleeping and dark light cycles via melatonin ( not really focusing on this) Parathyroid glands- ( next to thyroid) – four little glands that are right behind the thyroid gland and they are the size of a bb with a diameter of 1 or 2 mm each that secrete PTH Parathyroid hormone (PTH) is involved in calcium regulation Increase blood calcium level Osteocytes to break down bone and release calcium Reabsorption by kidney If extracellular calcium increases parathyroid secretion decreases Non-functioning parathyroid: hypoparathyroidism Tetany- involuntary contraction of muscles
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Types of Membrane Receptors Channels: typical of ionotropic receptors in synapses ( nicotinic, glutamate) G-protein coupled receptors ( traverses membrane seven times) neurotransmitter or hormone binds on the outside leading to effects Integrins: receptors that respond by affecting the cytoskeleton and are involved in cell to cell interactions Receptor is an enzyme: most important ones or most diverse ones are tyrosine kinases Ex: insulin receptor that when the hormone binds to the receptor on the outside it activates enzymatic activity on the inside that causes ATP to phosphorylate other proteins
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This note was uploaded on 03/10/2011 for the course BIPN 100 taught by Professor French during the Winter '07 term at UCSD.

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Endocrine System - Endocrine System Hormones ( I Hate...

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