3What happen inside our mouth? Mechanical digestionFood is cut up by the teeth and the pieces are mixed with the saliva by the tongue producing bolus.This cutting and mixing is called mastication (chewing)
4Types of Tooth Adults humans typically have 32 teeth Humans have 4 types of teeth:Incisors-cutting and bitingCanine-holding and cuttingPremolars-chewing and crushingMolars-chewing and crushing
5Tooth Structure Enamel: hardest tissue made of calcium salts. Dentine: forms the major part of the tooth. Contains a series of fine canals which extend to the pulp cavity.Pulp cavity: Contains tooth producing cells, blood vessels, nerve endings.Gum: Covers the junction between enamel and cement.Cement: helps anchor the tooth to the jaw.Periodontal membrane: Anchors the cement to jawbone. The tooth is held firmly but not rigidly.
6Dental Health Eating food with a low sugar content. Regular and effective brushing of teeth (at least twice a day).Finishing a meal with a crisp vegetable or fruit followed by rinsing with water.
8Chemical Digestion Digestive Enzymes Carbohydrate digestion begins in the mouth.Protein digestion begins in the stomach.Digestion of food molecules is completed in the small intestine.
9Function of other substances Region of gutDigestive juiceEnzymesSubstrateProductsOther substancesFunction of other substancesMouthSalivaSalivary amylaseStarchMaltoseHydrogencarbonateAlkaline environment for amylaseStomachGastric juicePepsin (protease)ProteinsPeptidesHydrochloric acidAcidic environment for pepsin; kills bacteriaSmall Intestine (duodenum)Pancreatic juiceBilePancreatic amylaseTrypsinLipaseNoneFats-Amino acidsFatty Acids & GlycerolBile saltsAlkaline environment for enzymesConverts globulets to smaller dropletsSmall intestine (ileum)Intestinal juiceMaltaseGlucose
10AbsorptionAbsorption is a process where digested food molecules are transported across the lining of the gut into the blood.Most absorption happens from the ileum.The surface of the ileum is highly folded into villi.
11STRUCTURE OF SMALL INTESTINE Epithelial cellsKeyNutrient absorptionVein carrying blood to hepatic portal vesselVilliLarge circular foldsIntestinal wallVeinBlood capillariesLactealMicrovilli (brush border)Muscle layers
12The liver and assimilation Digested food is absorbed into the bloodstream.The liver sorts out digested food molecules and make sure that the other tissues of the body receive what they need.The process of moving food molecules into the cells where they are used is called assimilation.
13Functions of Liver Manufacture of bile Storage of glucose as glycogen Acid chymeStomachPancreatic juicePancreasIntestinal juiceDuodenum of small intestineGall- bladderManufacture of bileStorage of glucose as glycogenInterconversion of amino acidsExcretion of excess amino acids and excreted in the urine as ureaBreakdown of alcohol and other toxinsRemoval of old red blood cells from the circulation and storage of the iron they contained
14Bread is made mainly of starch, protein and fat Bread is made mainly of starch, protein and fat. Describe what happens to the bread mechanically and chemically as it passes through the mouth, stomach and small intestine.