2. Liz Lauben 1 Digestion

3. 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

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

5. 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

6. 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

7. 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 or amino acids

8. 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

9. 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, one 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

10. 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

11. Liz Lauben 10