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BIPN100handout16 - BIPN100 Winter 2008 Dr Fortes Ann Shih...

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BIPN100 Winter 2008 Dr. Fortes Ann Shih [email protected] OH: Mon 10 – 11 Café Roma Handout 5 Endocrine System : 1. Cell to Cell Signalling : methods for communication A. Gap junctions: direct cytoplasmic transfer of electrical and chemical signals B. Local communication via chemicals that diffuse through the extracellular fluid i. Paracrine: chemical secreted by a cell to act on nearby cells ii. Autocrine: chemical that acts on the cell that secreted it C. Long distance communication via electrical signals carried by neurons and chemical signals transported in the blood i. Hormones: chemicals secreted into the blood to by circulated through the body ii. Neurohormones: chemicals released by neurons into the blood stream (neurocrine) 2. Types of Hormones (also table 7-1): Hydrophilic Hormones Hydrophobic Hormones Composition Peptides, proteins, amino acid derivatives (catecholamines) Steroid, thyroid, eicosanoid Examples Peptide: parathyroid hormone, insulin, hypothalamic, pituitary hormones, pancreatic hormones Amine: Catecholamines (NE, E, dopamine), melatonin Steriod: glucocorticoid (cortisol), mineralocorticoids (aldosterone), sex hormone (androgens, estrogens, progesterone) Thyroid: T3, T4 Can it cross phospholipid bilayer? No Yes Storage Stored in vesicles Made on demand Receptor Location Extracellular surface of plasma membrane Cytoplasmic (steroid) Nuclear (thyroid and steroid) Membrane (eicosanoid) Signal Transduction? Yes b/c it can’t cross membrane No, b/c it can act directly on the nucleus Short or Long Effects? Short Why? Long Why ? 3. Hormone receptor: Membrane Bound Intracellular Type 7-helix transmembrane G- protein coupled receptors Single Helix Transmembrane Receptor tyrosine kinase (RTKs) Nuclear R Binding of Hormone activates … GTP bond activate G α and G βγ , the subunits then activates 2 nd messenger pathways (know how G- protein activate and inactivate) Activate Tyrosine kinase
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