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Unformatted text preview: he Highlighted Questions are just the ones that haven’t been answered yet* BIO446L Exam 3 Study Guide Fall 2010 Endocrine Organs - Chapter 21 1. Define hormone, neurohormone, target cell, ligand, receptor, endocrine, paracrine and autocrine. a. Hormone- A chemical substance released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Controls and regulates the activity of certain cells or organs. A hormone is produced by an endocrine cell, released from that cell, picked up by the capillaries with pores in the tissue and then that hormone is carried to distant target cells via the blood. These are subdivided into three categories: peptides/proteins, steroids, and amines (catecholamines and thyroid hormones) . ◦ Peptides/proteins - synthesized and secreted by cells of the hypothalamus, pituitary gland, thyroid gland, parathyroid gland, and pancreas. Dissolves readily in the blood and generally do not require special transport proteins. ◦ Steroids - cholesterol-derived, synthesized and secreted by cells of the ovaries, testes and adrenal cortex. Released in the bloodstream and transported to target cells with the help of plasma proteins or specialized carrier proteins. These protect the hormone from degradation. ◦ Amino Acid/Amines - synthesized and secreted by many neurons as well as a variety of cells including the adrenal medulla. When released into circulation, catecholamines dissolve readily in the blood, in contrast to thyroid hormones that bind to “transthyretin” and “thyroxin-binding protein” b. Neurohormone- A hormone produced by a neurosecretory cell (like the chromaffin cells in the medulla). A hormone secreted by or acting on a part of the nervous system. Secreted by a specialized neuron into the bloodstream, the cerebrospinal fluid, or the intracellular spaces of the nervous system. Travels faster than hormones. EX: Thyrotropin Releasing Hormone, Gonadotropin Releasing Hormone, Adenocorticotropin Releasing Hormone, Oxytocin, Antidiuretic Hormone, Epinephrine c. Target Cell- the cells where hormones have their effect. Capable of responding to hormones because they bear receptors to which the hormone can bind. Hormones will float along the bloodstream until they find an appropriate target cell....
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This note was uploaded on 02/21/2012 for the course BIO 89515 taught by Professor Janmachart during the Fall '09 term at University of Texas.
- Fall '09