Download The Endocrine System - Animal Hormones

The Endocrine System - Animal Hormones
15MPark
May 7, 2013
The endocrine system plays an integral role in animal physiology. Animal hormones are integral ingredients in the
homeostatic maintenance of the organism’s body. This review is intended to engage one’s essay writing skills and
apply them to summarize key concepts regarding animal hormones.
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Part 1 - Homeostatic Function
Homeostatic maintenance of optimal glucose levels has been intensively studied in vertebrate organisms.
Question 1: Pancreatic hormones regulate blood glucose levels. Identify two pancreatic hormones and describe
the effect of each hormone on blood glucose levels. Finally, illustrate this homeostatic system via a diagram.
• Insulin (humulin)
• Glucagon
• Somatostatin
Question 2: For ONE of the hormones you identified in Question 1: Identify ONE target cell and discuss the
mechanism by which the hormones can alter activity in that target cell. Include in your discussion a description of
reception, cellular transduction, and response.
Insulin
• Any cell except red blood cells, or brain cells unless specified as neuroglial cells.
• Tyrosine kinase - formation of dimer
• Dimer and other proteins become phosphorylated.
• Stimulates a cascade pathway, mediated by a second messenger.
• Raises cellular uptake of glucose.
• Increases formation of glycogen from glucose in liver / skeletal muscle cells as intracellular glucose is incorporated
into glycogen (glycogenesis).
• Increases fat synthesis from glucose in liver cells and adipose tissue.
• Decreases gluconeogenesis, the conversion of amino acids and glycerol from fats to new molecules of glucose.
Glucagon
• Liver cells, skeletal muscle cells
• G-protein coupled receptors on liver cells - G protein-GTP activates adenylyl or guanalyl cyclase.
• cAMP or cGMP active as second messenger / phospholipase C activation release.
• Release glucose into the bloodstream from liver.
• Increases breakdown of glycogen glycogenolysis.
• Increases gluconeogenesis.
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