Chapter 15 - Chapter 15: The Endocrine System 1. How do...

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Chapter 15: The Endocrine System 1. How do endocrine glands differ from exocrine glands? Endocrine glands secrete tiny amounts of hormones directly into the bloodstream and not through ducts. This feature differentiates them from exocrine glands, which secrete their products onto epithelial surfaces through tiny tubes called ducts . 2. In what ways are the functions and characteristics of the endocrine system similar to those of the nervous system? In what ways are they different? Both systems regulate body functions to maintain homeostasis. The endocrine system’s reaction to stimuli is slow, whereas the reaction of the nervous system to stimuli is fast. The endocrine system’s duration of effects is long, whereas the duration of effects of the nervous system is short. The target tissues for the endocrine system are virtually all body cells and tissues, whereas the target tissues for the nervous system are muscle and glandular tissues. The chemical messengers of the endocrine system are hormones, whereas the chemical messengers of the nervous system are neurotransmitters. The messenger-producing cells of the endocrine gland are cells or modified neurons, whereas the messenger-producing cells of the nervous system are neurons. Distance from chemical message production to the target for the endocrine system is long (via the bloodstream), whereas this distance for the nervous system is short (across the synaptic space). 3. What is a hormone? Hormones are chemical messengers produced by endocrine glands and are secreted directly into blood vessels. 4. What is a hormone target? A cell that has receptors for a particular hormone is referred to as a target of that hormone. 5. How does a negative feedback system control the secretion of many hormones? A gland produces its hormone as a result of stimulation by another hormone. When the level of hormone from the first gland drops below needed levels, the second gland, the stimulating gland, produces more stimulating hormone, which stimulates the first gland to produce more of its hormone. The rising level of hormone from the first gland in the bloodstream eventually reaches the level required in the body. Once that level is reached, the production of stimulating hormone by the second gland is turned down. This reduces the stimulation of the first gland, causing it to produce less hormone. When the level of hormone from the first gland drops below what the body needs again, the second gland (stimulating gland) turns its production of hormone back up, which turns the production of hormone from the first gland back up, and the process continues. 6. Through what mechanisms does the hypothalamus control the production or release of hormones from the pituitary gland? How do its effects on the anterior and posterior portions of the pituitary differ? A system of tiny blood vessels called a
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This note was uploaded on 04/03/2012 for the course NRM 2406 taught by Professor Dabbert during the Spring '12 term at Texas Tech.

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Chapter 15 - Chapter 15: The Endocrine System 1. How do...

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