Lecture 5Outline of Last Lecture I. Planning a Healthy Diet (Chapter 2)Outline of Current LectureChapter 3: Digestion, Absorption, and TransportII. Digestiona. CHOb. Proteinc. Fatd. Muscular Action of DigestionIII. Absorption Nutrition 2380 IV. TransportCurrent LectureII. Digestion: Process by which food is broken down into absorbable units“take apart”Goals of Digestion: CHO -> fructose, glucose, galactose, PRO -> dipeptides, amino acids, FAT -> mono glycerides, fatty acids, glycerolDigestion starts in the mouth (ingestion), and ends in the anus (elimination)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Digestion of CHO:Mouth: Salivary amylase -> begins CHO digestionStomach: Stomach acid inactivates salivary amylase -> stop CHO digestionSmall Intestine: Digestion resumesPancreatic Amylases: From pancreatic duct to duodenumBrush Border Amylases: On surface of intestinal cellsIntestinal Maltase: Maltose -> glucose + glucose (breaks it down)Intestinal Sucrase: Sucrose -> glucose + fructoseIntestinal lactase: Lactose -> glucose + galactoseDigestion of Protein (PRO):Mouth: No PRO digestionStomach: Parietal Cells (secret HCl)Role of HCL:1. Uncoils PRO2. Activates pepsinogen to pepsinGoblet Cells: (Secrete mucus -> protects stomach from HCl)Small Intestine: Pancreatic and Intestinal proteases**What happens if someone has stomach cancer and has to get most of theirstomach remove? Think about it...Digestion of Fat:Mouth: lingual lipase, little fat digestion(The book says none, but there is proof of little)Stomach: Little fat digestionSmall Intestine: Where most of the breakdown occursBile: (Emulsifier = brings fats into suspension in water so that enzymescan break down the fat)Pancreatic LipasesIntestinal LipasesSaliva: Contains water, salts and enzymes -> moistens food, begin CHO di-gestionEnzymes: catalysts (speed up reactions), considered proteinsIdentified by organ they come from and compound they work onBile: Emulsifier, stored in the gallbladder and then sent to the small intestineBicarbonate: Neutralizes acidic gastric juiceHCl: described abovepH: Water=7, Stomach (gastric juice)=2**See Summary Table, pg. 76 in text (look it up for review)-A chart that puts all this togetherMuscular Action of Digestion: Peristalsis: Wavelike muscular contractions of the GI tract that push its con-tents alongStomach Action: Circular, longitudinal and diagonal musclesSegmentation: Circular muscles of intestines contract and squeeze contentsSphincter ContractionsIII. Absorption:Macronutrients: Digested, waiting to be absorbedMicronutrients: Waiting to be absorbedFiber: Not absorbedMost of the absorption occurs in the small intestine (designed for absorption)“surface area is the size of a tennis court”Small Intestine:Folds: Increases the surface area Villi: In constant motionCrypts: glands between the villi, important for secreting enzymesMicrovilli: hairlike projections which help trap nutrientsUnstirred Water Layer: Helps to hold the nutrients close to surfaceGoblet Cells: Secrete mucus and protect lining of small intestineIV. Transport:Water-Soluble Nutrients and Small Fats: Go to liver before being transported tother cellsFat Soluble Nutrients: Enter lymphatic