Exam 2 small text notes - Moving from Food to Nutrition to Nutrients Ingestion Digestion and Absorption Chapter 6 What Is Digestion and Why Is It

Exam 2 small text notes - Moving from Food to Nutrition to...

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Moving from Food to Nutrition to Nutrients Ingestion, Digestion and Absorption: Chapter 6 What Is Digestion and Why Is It Important? Digestion: The breakdown of foods into absorbable components in the gastrointestinal (GI) tract using mechanical and chemical means Occurs in the GI (Gastrointestinal) Tract Allows you to Absorb Nutrients from Foods To use food for energy, it must be broken down into molecules small enough to be absorbed. Digestion Occurs in the GI Tract The GI tract is a ~25-foot-long tube consisting of: Mouth Esophagus Stomach Small and large intestines Other organs The main roles of the GI tract are to: Break food down into its smallest components Absorb the nutrients Prevent microorganisms or other harmful compounds in foods from entering the tissues of the body Digestion is mechanical and chemical Mechanical Breaking down food through chewing and grinding Peristalsis Rhythmic muscular contractions that move food through the GI tract and mix it with enzymes Chemical Breaking down food with enzymes or digestive juices Digestion Allows You to Absorb Nutrients from Foods Absorption The process by which digested nutrients move into the tissues to be transported and used by the body’s cells. The body has two transport systems for absorption: The circulatory system The lymphatic system You digest and absorb 92 to 97 percent of the nutrients from your food. Animation: Overview of Digestion Absorption A lot of exam material from this, ex: surface area How Does Digestion Happen? You Begin Breaking Down Food in Your Mouth The Esophagus Propels Food into the Stomach The Stomach Stores, Mixes, and Prepares Food for Digestion Most Digestion and Absorption Occurs in the Small Intestine
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The Large Intestine Absorbs Water and Some Nutrients The Liver, Gallbladder, and Pancreas Are Accessory Organs How Does Digestion Happen? Begins before we eat Hunger and thirst Physical needs for food and water that drive how much and how often we eat Appetite A powerful drive to eat, but less reliable Influenced by environmental and psychological cues May cause eating without being hungry or needing nourishment Digestion and the Organs of the GI Tract You Begin Breaking Down Food in Your Mouth Saliva Watery substance produced by glands in the mouth, helps moisten and soften food. By chewing, your teeth grind the food into smaller pieces and mix it with saliva. Your tongue also helps mix food and saliva and pushes the food mass ( bolus ) to the back of the mouth into the pharynx . The epiglottis closes off the trachea during swallowing to prevent food from lodging in the windpipe.
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