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Digestion

Digestion. School of Education - CCNY. Introduction. Digestion is defined as the breakdown of nutrients We consume: Proteins Carbohydrates Fats These are broken down into their simplest forms. From Beginning to End. Mouth Esophagus

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Digestion

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  1. Digestion School of Education - CCNY Liz Lauben

  2. Introduction • Digestion is defined as the breakdown of nutrients • We consume: • Proteins • Carbohydrates • Fats • These are broken down into their simplest forms Liz Lauben

  3. From Beginning to End • Mouth • Esophagus • Stomach • Small intestine • Large intestine • Anus Liz Lauben

  4. Mouth • Mechanical digestion: the act of chewing • Carbohydrate digestion begins here • Saliva moistens food and contains the enzyme Salivary Amylase – breaks down complex carbs into simple sugars • Chemical Digestion: enzymes breaking down carbohydrates • Ball of moistened, partially digested food, known as the “BOLUS”, moves into the esophagus Liz Lauben

  5. Esophagus • Long tube through which “bolus” moves down into the stomach • The contraction of muscles pushes the food down – known as PERISTALSIS Liz Lauben

  6. Stomach • Protein digestion begins here • Gastric Glands: Parietal Cells Chief Cells • Chief Cells release HCl, the acidity kills foreign material and bacteria • Parietal Cells release the inactive enzyme Pepsinogen. This combines with HCl to create active form: Pepsin • Pepsin breaks down proteins into smaller polypeptide chains Liz Lauben

  7. Just a Reminder… • Both types of digestion are occurring in the stomach: Mechanical and Chemical • The churning of the stomach is considered mechanical digestion • The enzyme activity is considered chemical digestion • Chemical > Mechanical Liz Lauben

  8. Small Intestine • Continuation of Carbohydrate and Protein Digestion; beginning of Fat digestion • LIVER: releases bile that breaks down fats into fatty acids • PANCREAS: releases pancreatic juices, of which completes protein digestion (proteins to amino acids) and carbohydrate digestion (complex sugars into simple monosaccharides) • Absorption of simple nutrients through villi occurs here Liz Lauben

  9. Large Intestine • Unabsorbed material moves through large intestine, where water and salt are absorbed • This removal of liquid forms solid-like feces • Feces is stored in the colon • Feces is removed from the body, via the anus, by the process of ELIMINATION Liz Lauben

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