Lecture3

Lecture3 - Lecture#3 Endocrine System 16:47:00 ←...

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Unformatted text preview: Lecture #3 Endocrine System 08/07/2008 16:47:00 ← I.Endocrine Vs. Exocrine ← A. Endocrine • Horones • Bloodstream • Ductless ← B. Exocrine • Special body fluids (sweat, tears, saliva, bile, enzymes, mucus, breast milk) • Cavity/surface • Ducts • Paracrine : chemical signal diffuses across the extracellular fluid • ( ECF) between nearby cells • autocrine : chemical signal feeds back on signaling cell (gastrin) ← II. Signal transduction ← A. Receptors 1.intracellular receptors o Located inside cell o Hydrophobic chemical messengers 2. ligand-gated ion channels o Allow specific ion through in response to ligand binding change in permeability of membrane 3. Receptor enzymes o Activate or inactivate intracellular enzymes (cells talking to eachother) via phosphorylation cascades (add phosphate to an enzyme) proteins at each step phosphorylate or dephosphorylate other proteins signal amplification 4. G-protein coupled receptors: receptor interacts with G protein ← (figure 1) ← • pip-ca2+ signal transduction pathway o also uses G-protein o 2 nd messengers: IP3 +DAG ~ cause increase in intracellular (Ca2+) third messenger ~Ca2+ as major intracellular signaler ← III. Hormones= substances secreted by specialized cells (endocrine glands) that travels in the blood and causes a reaction in target cells • Active at very low concentrations • Involved in regulation (homeostasis), also development and behavior ← A. Peptide • Amino acids (cant cross membrane by itself~ hydrophillic) • Uses extracellular receptors (talk to outside of cell) • G-protein/2 nd messenger • Rapid effects • Modify enzyme activity • temporary ← B. Steroids • Cholesterol (hydrophobic) • Use intracellular receptors ~ pass right on through •...
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This note was uploaded on 07/23/2008 for the course BIO 131 taught by Professor Mostman during the Summer '08 term at UCSC.

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Lecture3 - Lecture#3 Endocrine System 16:47:00 ←...

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