Endocrine System Outline

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15: The Endocrine System Lecture Outline I. The Endocrine System: An Overview (pp. 518–519; Fig. 15.1) A. Endocrinology is the scientific study of hormones and the endocrine organs (p. 518; Fig. 15.1). 1. Hormones are chemical messengers that are released to the blood and elicit target cell effects after a period of a few seconds to several days. 2. Hormone targets include most cells of the body, and regulate reproduction, growth and development, electrolyte, water, and nutrient balance, cellular metabolism and energy balance, and mobilization of body defenses. 3. Endocrine glands have no ducts, and release hormones through diffusion. 4. Endocrine glands…show more content…
Hormones (pp. 520–525; Figs. 15.2–15.4) A. Chemistry of Hormones (p. 520) 1. Hormones are long-distance chemical signals that are secreted by the cells to the extracellular fluid and regulate the metabolic functions of other cells. 2. Most hormones are amino acid based, but gonadal and adrenocortical hormones are steroids, derived from cholesterol. 3. Eicosanoids, which include leukotrienes and prostaglandins, derive from arachidonic acid. B. Mechanisms of Hormone Action (pp. 520–522; Figs. 15.2–15.4) 1. Hormones typically produce changes in membrane permeability or potential, stimulate synthesis of proteins or regulatory molecules, activate or deactivate enzymes, induce secretory activity, or stimulate mitosis. 2. Water-soluble hormones (all amino acid–based hormones except thyroid hormone) exert their effects through an intracellular second messenger that is activated when a hormone binds to a membrane…show more content…
Mineralocorticoids, mostly aldosterone, are essential to regulation of electrolyte concentrations of extracellular fluids. 2. Aldosterone secretion is regulated by the renin-angiotensin mechanism, fluctuating blood concentrations of sodium and potassium ions, and secretion of ACTH. 3. Glucocorticoids are released in response to stress through the action of ACTH. 4. Gonadocorticoids are mostly weak androgens, which are converted to testosterone and estrogens in the tissue cells * Medulla (neurosecretory) The adrenal medulla contains chromaffin cells that synthesize epinephrine and norepinephrine (pp. 542–544; Figs. 15.13, 15.16; Table 15. * Catecholamines (epinephrine[adrenaline]) VII. The Pineal Gland (p. 544) Pineal Melatonin A. The only major secretory product of the pineal gland is melatonin, a hormone derived from serotonin, in a diurnal cycle (p.

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