sci241_week2_reading1[1] - (Luis Real/Age Fotostock America...

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(Luis Real/Age Fotostock America, Inc.) C H A P T E R 3 C O N C E P T S All plant and animal life is made up of cells, which form tissues that compose the organs and organ systems of a living organism. The food we eat is digested in the gastrointestinal tract and its nutrients are absorbed into the body. Hormones released into the blood and enzymes released into the gastrointestinal tract facilitate the digestion of food and the absorption of nutrients. Digestion begins in the mouth. Food is then swallowed and moves down the esophagus to the stomach for storage and further digestion. The small intestine is the primary site of digestion and absorption. Water-soluble materials are absorbed into the blood. Most fat-soluble materials are absorbed into the lymph. Changes in the gastrointestinal tract can alter digestion and absorption and affect nutritional status. Nutrients delivered to the cells can be used to produce energy in the form of ATP and to synthesize molecules for immediate use or for storage. Materials that are not absorbed pass into the large intestine and are excreted in feces. The waste products generated inside the body by metabolism are eliminated via the lungs, skin, and kidneys. Why does your mouth water at the sight or smell of food? Why are you hungry very soon after eating some meals while others stick with you longer? Is it healthy to have bacteria living in your gastrointestinal tract? J u s t A T a s t e
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WebMD Feature Archive Bariatric Surgery: A Radical Obesity Fix By Catherine Guthrie Dec. 18, 2000—Two years ago, Rhonda Bailey was fat and miserable. The 38-year-old bore 245 pounds on her 5-foot-1 frame. Squeezing into a restaurant booth, airplane seat, or amusement park ride was unimaginable. Walking made her joints stiff and sore. She leaned heavily on a cane to get from the handicapped parking space to her desk at work. Today, Bailey is literally half the woman she used to be. Over the past 18 months, she has shed 50% of her body weight. Her waist shrunk from a size 26 to a size six. Now, at 125 pounds, the Southern California resident jogs daily, bicycles with her stepdaughter, and rejoices in her ability to do life’s little things—like tying her shoes— without asking her husband for help. Bailey’s secret isn’t the latest fad diet or radical weight loss drug. She owes her slimmed-down body to gastric-bypass surgery. The procedure is just one of several weight loss operations that fall under the heading of bariatric surgery. As obesity rates creep skyward, so do the number of Americans turning to surgery as a weight loss tool. To read the rest of this article, go to article/14/1689_51239.htm. 55 3 The Digestive System: From Meals to Molecules Our Complex Bodies Are Built from Simpler Units Cells Form Tissues, Tissues Form Organs, Organs Form Organ Systems Organ Systems Work Together to Digest, Absorb, and Utilize Nutrients The Digestive System Digests Food and Absorbs Nutrients
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