chapter3-2

Chapter3-2 - Chapter Summary for Nutrition Concepts and Controversies 11e Chapter 3 The Remarkable Body The body's cells need energy oxygen and

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Chapter Summary for  Nutrition: Concepts and Controversies  11e Chapter 3 – The Remarkable Body The body’s cells need energy, oxygen, and nutrients, including water, to remain healthy and do their work. Genes direct the making of each cell’s machinery, including enzymes. Genes and nutrients interact in ways that affect health. Specialized cells are grouped together to form tissues and organs; organs work together in body systems. Blood and lymph deliver nutrients to all the body’s cells and carry waste materials away from them. Blood also delivers oxygen to cells. The cardiovascular system ensures that these fluids circulate properly among all organs. Glands secrete hormones that act as messengers to help regulate body processes. The nervous system joins the hormonal system to regulate body processes through communication among all the organs. Together, the hormonal and nervous systems respond to the need for food, govern the act of eating, regulate digestion, and call for the stress response. A properly functioning immune system enables the body to resist diseases. The preference for sweet, salty, and fatty tastes seems to be inborn and can lead to overconsumption of foods that offer them. The digestive tract is a flexible, muscular tube that digests food and absorbs its nutrients and some nonnutrients. Ancillary digestive organs aid digestion. The digestive tract moves food through its various processing chambers by mechanical means. The mechanical actions include chewing, mixing by the stomach, adding fluid, and moving the tract’s contents by peristalsis. After digestion and absorption, wastes are excreted. Chemical digestion begins in the mouth, where food is mixed with an enzyme in saliva that acts on carbohydrates. Digestion continues in the stomach, where stomach enzymes and acid break down protein. Digestion progresses in the small intestine; there the liver and gallbladder contribute bile that emulsifies fat, and the pancreas and small intestine donate enzymes that continue digestion so that absorption can occur. Bacteria in the colon break down certain fibers. The healthy digestive system is capable of adjusting to almost any diet and can handle any combination of foods with ease. The mechanical and chemical actions of the digestive tract break down foods to nutrients, and large nutrients to their smaller building blocks, with remarkable efficiency. The digestive system feeds the rest of the body and is itself sensitive to malnutrition. The folds and villi of the small intestine enlarge its surface area to facilitate nutrient absorption through countless cells to the blood and lymph. These transport systems then deliver the nutrients to all the body’s cells. The digestive tract has many ways to communicate its needs. Maintenance of a healthy digestive tract requires
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This note was uploaded on 07/01/2011 for the course NTR 101 taught by Professor Hendry during the Spring '10 term at Holyoke CC.

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Chapter3-2 - Chapter Summary for Nutrition Concepts and Controversies 11e Chapter 3 The Remarkable Body The body's cells need energy oxygen and

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