2Food types Type Found in Uses Carbohydrates Fats Proteins Vitamins 01/04/2017TypeFound inUsesCarbohydratesFatsProteinsVitaminsMineralsFibreWaterBread, potatoes, cerealEnergyCream, butter, milk, oilA store of energyMeat, fish, eggsBuilding and repairing cellsVegetables, cerealKeep things “ticking over”Meat, milk, cerealStrong teeth etcFruit + veg, cerealKeeps you regular!Water!75% of the body is water
3Food tests 101/04/2017To investigate what happens in digestion we need to be able to test for different foods. Here are two simple tests:IodineThe test for starch:Drop some iodine onto the food. If the iodine turns BLUE/BLACK then STARCH is present.The test for simple sugars (e..g glucose)Boil the food with some Benedict’s solution. If an orange “precipitate” appears then the food contains simple sugars
4Food tests 2 The test for protein: 01/04/2017The test for protein:Add 5cm3 of dilute sodium hydroxide followed by 5cm3 of dilute copper sulphate. If protein is present it will produce a purple colour.The test for fats:Shake the food with about 10cm3 of ethanol in a test tube. Pour some of the solution into a tube containing water. If fat is present the water will turn cloudy white.
5Utilisation of foodHumans ingest oragnic food via process of holozoic nutrition which includes:Ingestion: act of taking in food via mouthDigestion: Breakdown of complex to simple soluble moleculesAbsorption: Diffusion of molecules into blood to liverAssimilation: use of food by body for respiration growth devlpmt, diffused from small intestines to b.v. which than carry nutrients where neededEgestion: process of undigested food removed from body- defecation
6The digestive systemThe digestive system is responsible for breaking down large, complex food substances into smaller, simpler and soluble molecules.The digestive system in humans is a long tube called the alimentary canal,8-9m long, that starts at the mouth and ends at the anus.Mucus lined to reduce friction
7Digestion Digestion occurs by two processes: Physical digestion Chemical digestionPhysical digestion is the physical breakdown of food into smaller pieces.Chemical digestion is the change of the food into simpler substances
8Physical digestionPhysical digestion is the physical breakdown of food into smaller pieces. This process occurs in the mouth and also the stomachThe mouth breaks down food by chewing. Teeth and tongue are involved in this process.
901/04/2017It also occurs in the stomach when stomach muscles churn food and further breaks it down into smaller pieces called chyme
10Physical Digestion :TEETH 01/04/2017Teeth formula depending on location and number in mouth:I 2/2 C 1/1 P 2/2 M 3/3
11Teeth Observe shape Observe bumps on enamel to differentiate molars 01/04/2017Observe shapeObserve bumps on enamel to differentiate molarsDifferent shapes of teeth have different functions
12Teeth incisors: chisel and cut Canine: rip and tear 01/04/2017incisors: chisel and cutCanine: rip and tearMolars/ premolars: grind and crush2 sets:decidous; milk teeth 20Permanent; Adult teeth , consists of 32 including wisdom
14Function of parts01/04/2017Enamel: hard white outer layer protects, dead, visible part of teeth and part of crownDentine : found below enamel , living, main part of toothPulp cavity:Nerve endings connect to brain, blood vessels carry oxygen and nutrients to cells and waste away
15Function of parts Jaw bone: is the based to which teeth are attached. 01/04/2017Jaw bone: is the based to which teeth are attached.Cement: grips teeth , holds tooth in place
16The digestive system01/04/2017The whole point of digestion is to break down our food so that we can get the bits we need from it…
18Identify and tell the function of each part of the digestive system MouthTeeth bite off and chew food into a soft pulp that is easy to swallow.Chewing mixes the food with saliva, from salivary glands around the mouth and face, to make it moist and easy to swallow.
19Identify and tell the function of each part of the digestive system MouthEnzymes in the saliva begin digestion of carbohydrates.
20Identify and tell the function of each part of the digestive system EsophagusThe esophagus is a muscular tube. It takes food from the throat and pushes it down through the neck, and into the stomach.It moves food by waves of muscle contraction called peristalsis.
21Identify and tell the function of each part of the digestive system StomachThe stomach has thick muscles in its wall. These contract to mash the food into a water soup called chyme.The stomach lining produces strong digestive juices.
22Identify and tell the function of each part of the digestive system StomachThese create chemical reactions in the stomach, breaking down and dissolving its nutrients.
23Identify and tell the function of each part of the digestive system Small IntestineThis part of the digestive tract is narrow, but very long - about 20 feet.Enzymes continue the chemical reactions on the food.
24Identify and tell the function of each part of the digestive system Small IntestineThe nutrients are broken down small enough to pass through the lining of the small intestine, and into the blood (diffusion).Nutrients are carried away to the liver and other body parts to be processed, stored and distributed.
25The small intestine01/04/2017This is where the “small parts” are absorbed into our blood stream…Everything else passes into the large intestineGlucose gets absorbed into the blood
26Identify and tell the function of each part of the digestive system Large IntestineUseful substances that were not absorbed in the small intestine, such as spare water and body minerals, are absorbed through the walls of the large intestine, back into the blood.
27Identify and tell the function of each part of the digestive system Large IntestineThe remains are formed into brown, semi-solid feces, ready to be removed from the body
28Identify and tell the function of each part of the digestive system Rectum and AnusThe end of the large intestine and the next part of the tract, the rectum, store the feces.Feces are finally squeezed through a ring of muscle, the anus, and out of the body.
29Identify and tell the function of each part of the digestive system PancreasThe pancreas, like the stomach, makes digestive juices called enzymes which help to digest food further as it enters the small intestines.
30Identify and tell the function of each part of the digestive system Gall BladderA small baglike part under the liver.It stores a fluid called bile, which is made in the liver.
31Identify and tell the function of each part of the digestive system Gall BladderAs food from a meal enters the small intestine, bile flows from the gall bladder along the bile duct into the intestine.It helps to digest fatty foods and also contains wastes for removal.
32Identify and tell the function of each part of the digestive system LiverBlood from the intestines enters to the liver, carrying nutrients, vitamins and minerals, and other products from digestion.
33Identify and tell the function of each part of the digestive system LiverThe liver is like a food-processing factory with more than 200 different jobs. It stores some nutrients, changes them from one form to another, and releases them into the blood according to the activities and needs of the body.
34Liver Not part of alimentary canal but plays a role in digestion. 01/04/2017Not part of alimentary canal but plays a role in digestion.Connected to ileum by hepatic portal veinDecides whether to store or send nutrients to body cellsMajority of fatty acids transported by Lacteals (lymphatic system which eventually connects back to blood vessels)
35Found under diaphragm overlapping stomach. Made up of lobes 01/04/2017Found under diaphragm overlapping stomach.Made up of lobesRich blood supply from Hepatic portal :vein and arteryRecieves mainly a.a. and glucoseExcess glucose converted into glycogen here and reconverted and released when need by bloodExcess a.a toxic, Altered to urea via process of Deamination
3601/04/2017Urea (nitrogenous waste) is removed from liver sent to kidneys to be removed as urine
37To quiz yourself over the parts of the digestive system, go to website
38Chemical digestionChemical digestion also starts in the mouth and continues in the stomach and small intestinesChemical digestion occurs with the aid of enzymes, biological catalysts.FoodSimpler substanceCarbohydrates, starch ( polysaccharides)Glucose, maltose, lactosePrtoeinsAmino acidsLipids ( fats)Fatty Acids and glycerol
39ENZYMESAre proteinsSpecific to particular substrate; Induced fit, lock and key mechanismRequired in small amounts, can be reusedWork best at an optimum temp; fastest rate of rxnWork best at particular pH : optimum pH
40Rxn occur quickly, each 10 degree temp rise, doubles rate of rxn ENZYMES01/04/2017Are inhibited or prevented from working by poisons like arsenic , cyanideRxn occur quickly, each 10 degree temp rise, doubles rate of rxnDenatured at high temperatures, therefore enzyme structure is compromised no rxn occurs.Most enzymes work best around a neutral pH but 2.5,
41Words – blood, lipids, proteins, digestion, starch, smaller Enzymes01/04/2017Enzymes are chemicals produced by the body to help _______. When they react with food they break it down into ______ pieces which can then pass into the ______:Carbohydrase breaks _______ (a carbohydrate) down into glucose:Protease breaks _______ down into amino acids:Lipase breaks fats (_____) down into fatty acids and glycerol:Words – blood, lipids, proteins, digestion, starch, smaller
42Part of digestive system Food substance acted on 01/04/2017Part of digestive systemFood substance acted onEnzyme used and pH of environmentproductsMouthvia salivaCarbohydratesAmylase( ) pHGlucoseStomachacidic environs provided by HCl secreted from vesicles in stomach lining : acidic pHProteins:Pepsin(acidic environ) pH2-3RenninAmino acidsLiquid milk to solidSmall intestines; doesn’t produce enzymes they are all obtained from pancreatic juiceCarbs, rest of proteins, fatsAmylase sucrase, maltase, lactase, trypsin (pH ), lipase, peptidaseGlucose, amino acids, Fatty acids and glycerol.