Do Now1. Describe the main function of all organs of the digestive system.2. Where would the digestion of starch start? Why?3. Which nutrients do you think could be absorbed without being digested in the gastrointestinal tract? Why?
Do Now1. To break food down into usable form so it can be transported and2. Starch is a complex carbohydrate Digestion of sugars start in the mouth3. Vitamins, Minerals, and Water There aren’t any building blocks for these!
Objective: What happens to foodafter it moves out of the stomach?
A trip through the Gastrointestinal Tract: Food enters through the mouth Become a bolus in the esophagus Becomes chyme when entering the stomach
After the stomach… CHYME enters the small intestines
Small Intestines Main Function: Absorption of nutrients occurs here! The surface of small intestines are covered with VILLI The surfaces of the villi are covered by MICROVILLI Digestion is finished here; no digestion after
Which set of paper towels can absorb more?
Small Intestines Villi and Microvilli (villus and microvillus) How do villi and microvilli affect the surface area of the S? Make the small intestine have HUGE SURFACE AREA…why? So the most possible absorption of nutrients can take place! Microvilli are like small fingers on finger! Huge surface area!
After the small intestine… Food enters the large intestine (aka colon) Once food enters the large intestine, most of the nutrients have already been absorbed. Predict what’s left: Water, undigested foods, plant sugar
Large Intestine (Colon) Main function: Absorbing Water Predict what happens water cannot be absorbed: Diarrhea Think about it: if you don’t absorb the water, where would it go? To help food move better – Roughage Complex carbs, fiber, vegetables good sources of roughage
Enzymes in the Gastrointestinal System Mouth – Salivary amylase Breaks down starches into simple sugars Where carbohydrate chemical digestion starts Stomach – pepsin Breaks down proteins into amino acids Where protein chemical digestion starts
Enzymes in the Digestive System Small intestine gets enzymes from two places: 1. the pancreas releases enzymes 2. the small intestine lining secretes enzymes
Enzymes in the Digestive System Pancreas releases into small intestines: Amylase – continues breakdown of carbohydrate, starch Trypsin – continues breakdown of protein Lipase – STARTS break down of fat NOTICE: lipase (lipid); fat chemical digestion starts in the small intestine Small intestine releases from its lining Maltase, sucrase, lactase – breaks down carbs to sugars Peptidase – breaks down peptides into amino acids