Hormones_and_Digestion

Hormones_and_Digestion - 1>ENAnimal...

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Unformatted text preview: 1->ENAnimal Hormones->ENHormonesare chemical signals secreted by cells of the endocrine system.Endocrine cells: cells that secrete hormonesTarget cells: cells that have receptors for the hormones->ENCirculating hormonesdiffuse into the blood and can activate target cells far from the site of release.Paracrinehormones: affect only target cells near the site of release.Autocrinehormones: affect the cells that released the hormones.->ENFigure 41.1 Chemical Signaling Systems (Part 1)2->ENFigure 41.1 Chemical Signaling Systems (Part 2)->ENSome endocrine cells are single cells (e.g., in the digestive tract.)Endocrine glands: aggregations of secretory cells. Hormones are secreted to the extracellular space.Exocrine glands: ducts carry products to the outside of the body.->ENChemical communication arose early in evolution.Plants, sponges, protistsall use chemical signals.In arthropods, hormones control molting and metamorphosis. ->ENArthropods: the rigid exoskeleton is shed during moltsto allow growth. Growth stages between molts are called instars.3->ENFigure 41.2 Diffusible Substance Triggers Molting ->ENFigure 41.2 Diffusible Substance Triggers Molting->ENTwo hormones regulate molting:PTTH (prothoracicotropichormone) from cells in the brain. Stimulates the prothoracicgland to secrete ecdysone.Ecdysonediffuses to target tissues and stimulates molting.->ENThe nervous system and hormonal system are linked.Nervous system (brain) controls the endocrine gland (prothoracicgland), which produces the ecdysonethat orchestrates the physiological response. 4->ENJuvenile hormone: also released from the brain—prevents maturation to adult form.Control of development by juvenile hormone important in insects with complete metamorphosis.->ENFigure 41.3 Complete Metamorphosis->ENThree types of hormones:•Peptides or polypeptides: water-soluble, transported in blood but not across membranes.•Steroid hormones: lipid-soluble; must be bound to carrier proteins to be carried in blood.•Amine hormones: derivatives of tyrosine->ENHormone receptors:•Lipid soluble hormones: receptors are inside the cell•Water-soluble hormones cannot readily pass cell membrane—receptors are on the outside5->ENReceptors are glycoproteins with three domains:•Binding domain: projects outside plasma membrane•Transmembrane domain•Cytoplasmic domain: extends into cytoplasm—initiates target cell response->ENOne hormone can trigger different responses in different types of cells.Example: epinephrine(amine), fight-or-flightresponse ->ENFigure 41.5 The Endocrine System of Humans (Part 1)->ENFigure 41.5 The Endocrine System of Humans (Part 2)6->ENThe pituitary glandis attached to the hypothalamusof the brain.Posterior pituitarysecretes neurohormones(synthesized by neurons in the hypothalmus): oxytocinand ADH.->ENFigure 41.6 The Posterior Pituitary Releases Neurohormones->ENThe anterior pituitarysecretes:•Tropic hormones: control other endocrine glands•Growth hormone: promotes growth•...
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This note was uploaded on 10/08/2010 for the course MCDB MCDB 1B taught by Professor Weimbs,finklestein during the Summer '09 term at UCSB.

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Hormones_and_Digestion - 1>ENAnimal...

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