Anatomy and Physiology Answer Key

Anatomy and Physiology Answer Key

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Unformatted text preview: e because it readies the body for the extra work it might have to do in terms of increased breathing rate, heart rate, and muscular activity. It prepares the body to most efficiently flee or defend itself. 2. (a) A prolonged period of stress triggers release of ACTH from the pituitary (mediated by the hypothalamus) and brings about the release of glucocorticoids from the adrenal cortex. These mediate suppression of the immune system and metabolism of fats and proteins, which helps Control of Blood Glucose (page 101) 1. (a) Stimulus: Rise in the levels of glucose in the blood above a set level (about 5.5 mmol per L). (b) Stimulus: Fall in blood glucose levels below a set level (about 3.5 mmol per L). (c) Glucagon brings about the production (and subsequent release) of glucose from the liver by the breakdown of glycogen and the synthesis of glucose from amino acids. (d) Insulin increases glucose uptake by cells (thereby lowering blood glucose) and brings about production of glycogen and fat from glucose in the liver. Biozone International 2009 Photocopying Prohibited 17 2. 3. Fluctuations in blood glucose (BG) and blood insulin levels are closely aligned. Following a meal, BG rises sharply and there is a corresponding increase in blood insulin, which promotes cellular glucose uptake and a subsequent fall in BG. This pattern is repeated after each meal, with the evening meal followed by a gradual decline in BG and insulin over the sleep (fasting) period. Negative feedback mechanisms prevent excessive fluctuations in blood glucose (BG) throughout the 24 hour period. 2. (a) Veins have less elastic and muscle tissue than arteries. (b) Veins have a larger lumen than arteries. 2. Most of the structural differences between arteries and veins are related to the different blood pressures inside the vessels. Blood in veins travels at low pressure and veins do not need to be as strong, hence the thinner layers of muscle and elastic tissue and the relatively larger lumen. Extra note: There is still enough e...
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This document was uploaded on 01/28/2014.

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