Week 4, 5

  1. Digestive System: Organs and their function.

Function of the Digestive System
Nutrients in the foods you eat are needed by the cells of your body. How do the nutrients in foods get to your body cells? What organs and processes break down the foods and make the nutrients available to cells? The organs are those of the digestive system. The processes are digestion and absorption. The digestive system is the body system that breaks down food and absorbs nutrients. It also gets rid of solid food waste

Digestion is the process of breaking down food into nutrients. There are two types of digestion, mechanical and chemical. In mechanical digestion, large chunks of food are broken down into small pieces. Mechanical digestion begins in the mouth and involves physical processes, such as chewing. Inchemicaldigestion, large food molecules are broken down into small nutrient molecules. This is a chemical process which also begins in the mouth as saliva begins to break down food. Absorptionistheprocessthatallowssubstancesyoueattobetakenupbytheblood. Afterfoodisbrokendowninto small nutrient molecules, the molecules are absorbed by the blood. After absorption, the nutrient molecules travel in the bloodstream to cells throughout the body. Somesubstancesinfoodcannotbebrokendownintonutrients. Theyremainbehindinthedigestivesystemafterthe nutrients are absorbed. Any substances in food that cannot be digested and absorbed pass out of the body as solid waste. The process of passing solid food waste out of the body is calledelimination.
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www.ck12.org Chapter 1. Human Biology
Vocabulary
• absorption: Process that allows nutrients to be taken up by the blood. • chemical digestion: Process by which large food molecules are broken down into small nutrient molecules through a chemical process. • digestion: Process of breaking down food into nutrients. • digestive system: Body system that breaks down food, absorbs nutrients, and rids the body of solid food waste. • elimination: Process of passing solid food waste out of the body. • mechanical digestion: Process by which large chunks of food are broken down into small pieces through a physical process, such as chewing. • saliva: Watery substance located in the mouths of organisms, secreted by the salivary glands.
Summary
• Thedigestivesystemisthebodysystemthatbreaksdownfood,absorbsnutrients,andgetsridofsolidwastes. • Digestion is the process of breaking down food into nutrients, while absorption is the process that allows nutrients to be taken up by the blood.