The following sections of this BookRags Literature Study Guide is offprint from Gale's For Students Series: Presenting Analysis, Context, and Criticism on Commonly Studied Works: Introduction, Author Biography, Plot Summary, Characters, Themes, Style, Historical Context, Critical Overview, Criticism and Critical Essays, Media Adaptations, Topics for Further Study, Compare & Contrast, What Do I Read Next?, For Further Study, and Sources.
(c)1998-2002; (c)2002 by Gale. Gale is an imprint of The Gale Group, Inc., a division of Thomson Learning, Inc. Gale and Design and Thomson Learning are trademarks used herein under license.
The following sections, if they exist, are offprint from Beacham's Encyclopedia of Popular Fiction: "Social Concerns", "Thematic Overview", "Techniques", "Literary Precedents", "Key Questions", "Related Titles", "Adaptations", "Related Web Sites". (c)1994-2005, by Walton Beacham.
The following sections, if they exist, are offprint from Beacham's Guide to Literature for Young Adults: "About the Author", "Overview", "Setting", "Literary Qualities", "Social Sensitivity", "Topics for Discussion", "Ideas for Reports and Papers". (c)1994-2005, by Walton Beacham.
All other sections in this Literature Study Guide are owned and copyrighted by BookRags, Inc.
Epinephrine is a hormone that is produced by the medulla of the adrenal glands that is an important component in the regulation of the sympathetic branch of the autonomic nervous system. Epinephrine is also known as adrenaline in some publications, especially those using British English.
Both norepinephrine (a neurotransmitter) and epinephrine are derived from the amino acid tyrosine.
In general, epinephrine causes and elevation of blood pressure, heart rate, and oxygen consumption, all important components in the fight or flight response.
Within the liver, epinephrine causes the release of stored glycogen sugars and results in an elevation in blood glucose. Within intact liver cells, epinephrine stimulates enzyme activity (e.g., the activity of glycogen phosphorylase) that cause the breakdown of liver glycogen to blood glucose. At the tissue level, epinephrine also acts to increase the rate of metabolism of glycogen.
American physiologist Earl Sutherland and others, in a series of experiments conducted in the 1950s, demonstrated in vitro (in the laboratory) the effects of epinephrine on liver tissue. Research on epinephrine led to the identification of the biologic role of cyclic AMP (adenylic acid) and adenylate cyclase.
There are specific disorders that can lead to diminished production or deficits of epinephrine (e.g., Addison's disease of the adrenal glands). Other adrenal irregularities and tumors may result in the overproduction of epinephrine.
Epinephrine can also be produced synthetically and can be given to patients as a vasoconstrictor to constrict blood vessels and reduce blood loss. Epinephrine is used to counter the effects of anaphylactic shock (a severe allergic reaction) during which blood pressure falls to low levels and there is a loss of blood flow to vital organs. Epinephrine is also used as a cardiac stimulant.