Nderstanding Chemical Signals

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Chapter 28 Homework - Understanding Chemical Signals Answer the following questions in a separate document and submit them to your instructor. 1. Prolonged stress, like studying for an exam, triggers the release of the lipophilic hormone cortisol from the adrenal cortex. A. Explain the steps that lead to the synthesis and release of cortisol. B. Which of the hormones involved in cortisol release are tropic? C. How is the chemical signal of cortisol received by the target cells? 2. Proper blood glucose maintenance is important for proper health. Blood glucose maintenance is controlled by two antagonistic hydrophilic hormones: insulin and glucagon. When blood glucose levels aren't properly regulated diabetes mellitus occurs. A. Where are insulin and glucagon produced? B. Explain how insulin and glucagon regulate the blood glucose level. C. How are the chemical signals of insulin and glucagon received by the target cells? D. Explain the causes of diabetes mellitus type I and type II. (1) Answer A: Prolonged stress is conveyed to neurons in the hypothalamus of the brain. The hypothalamus produces a releasing hormone, which is secreted into the blood supply of the anterior pituitary gland. This causes the anterior pituitary gland to produce and secrete a hormone (adrenocorticotropic hormone) that travels through the circulatory system. When the hormone reaches the adrenal cortex it binds to a cell-surface receptor, which signals the synthesis and release of cortisol. Answer B: A tropic hormone stimulates the synthesis and secretion of a hormone by another endocrine gland. The releasing hormone secreted by the hypothalamus stimulates the release of a hormone by the anterior pituitary, so it is a tropic hormone. The hormone secreted by the anterior pituitary stimulates the secretion of a hormone by the adrenal cortex, so it is also a tropic hormone.

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