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13/06/2014 Food and Digestion. 13/06/2014 Food types Type Found in Uses Carbohydrates Fats Proteins Vitamins Minerals Fibre Water Bread, potatoes, cereal.

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Presentation on theme: "13/06/2014 Food and Digestion. 13/06/2014 Food types Type Found in Uses Carbohydrates Fats Proteins Vitamins Minerals Fibre Water Bread, potatoes, cereal."— Presentation transcript:

1 13/06/2014 Food and Digestion

2 13/06/2014 Food types Type Found in Uses Carbohydrates Fats Proteins Vitamins Minerals Fibre Water Bread, potatoes, cereal Cream, butter, milk, oil Meat, fish, eggs Vegetables, cereal Meat, milk, cereal Fruit + veg, cereal Water! Energy A store of energy Building and repairing cells Keep things ticking over Strong teeth etc 75% of the body is water Keeps you regular!

3 13/06/2014 Food tests 1 To investigate what happens in digestion we need to be able to test for different foods. Here are two simple tests: 1)The test for starch: Drop some iodine onto the food. If the iodine turns BLUE/BLACK then STARCH is present. 2)The test for simple sugars (e..g glucose) Boil the food with some Benedicts solution. If an orange precipitate appears then the food contains simple sugars Iodine

4 13/06/2014 Food tests 2 1)The 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. 2)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.

5 Utilisation of food Humans ingest oragnic food via process of holozoic nutrition which includes: –Ingestion: act of taking in food via mouth –Digestion: Breakdown of complex to simple soluble molecules –Absorption: Diffusion of molecules into blood to liver –Assimilation: use of food by body for respiration growth devlpmt, diffused from small intestines to b.v. which than carry nutrients where needed –Egestion: process of undigested food removed from body- defecation

6 The digestive system The 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

7 Digestion Digestion occurs by two processes: a)Physical digestion b)Chemical digestion Physical digestion is the physical breakdown of food into smaller pieces. Chemical digestion is the change of the food into simpler substances

8 Physical digestion Physical digestion is the physical breakdown of food into smaller pieces. This process occurs in the mouth and also the stomach The mouth breaks down food by chewing. Teeth and tongue are involved in this process.

9 It also occurs in the stomach when stomach muscles churn food and further breaks it down into smaller pieces called chyme 13/06/2014

10 Physical Digestion :TEETH Teeth formula depending on location and number in mouth: –I 2/2 C 1/1 P 2/2 M 3/3 13/06/2014

11 Teeth Observe shape Observe bumps on enamel to differentiate molars Different shapes of teeth have different functions 13/06/2014

12 Teeth incisors: chisel and cut Canine: rip and tear Molars/ premolars: grind and crush 2 sets: » decidous; milk teeth 20 »Permanent; Adult teeth, consists of 32 including wisdom 13/06/2014

13 Structure of teeth 13/06/2014

14 Function of parts Enamel: hard white outer layer protects, dead, visible part of teeth and part of crown Dentine : found below enamel, living, main part of tooth Pulp cavity:Nerve endings connect to brain, blood vessels carry oxygen and nutrients to cells and waste away 13/06/2014

15 Function of parts Jaw bone: is the based to which teeth are attached. 13/06/2014 Cement: grips teeth, holds tooth in place

16 13/06/2014 The digestive system The whole point of digestion is to break down our food so that we can get the bits we need from it…

17 13/06/2014

18 Identify and tell the function of each part of the digestive system Mouth Teeth 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.

19 Identify and tell the function of each part of the digestive system Mouth Enzymes in the saliva begin digestion of carbohydrates.

20 Identify and tell the function of each part of the digestive system Esophagus The 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.

21 Identify and tell the function of each part of the digestive system Stomach The 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.

22 Identify and tell the function of each part of the digestive system Stomach These create chemical reactions in the stomach, breaking down and dissolving its nutrients.

23 Identify and tell the function of each part of the digestive system Small Intestine This part of the digestive tract is narrow, but very long - about 20 feet. Enzymes continue the chemical reactions on the food.

24 Identify and tell the function of each part of the digestive system Small Intestine The 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.

25 13/06/2014 The small intestine This is where the small parts are absorbed into our blood stream… Glucose gets absorbed into the blood Everything else passes into the large intestine

26 Identify and tell the function of each part of the digestive system Large Intestine Useful 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.

27 Identify and tell the function of each part of the digestive system Large Intestine The remains are formed into brown, semi-solid feces, ready to be removed from the body

28 Identify and tell the function of each part of the digestive system Rectum and Anus The 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.

29 Identify and tell the function of each part of the digestive system Pancreas The pancreas, like the stomach, makes digestive juices called enzymes which help to digest food further as it enters the small intestines.

30 Identify and tell the function of each part of the digestive system Gall Bladder A small baglike part under the liver. It stores a fluid called bile, which is made in the liver.

31 Identify and tell the function of each part of the digestive system Gall Bladder As 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.

32 Identify and tell the function of each part of the digestive system Liver Blood from the intestines enters to the liver, carrying nutrients, vitamins and minerals, and other products from digestion.

33 Identify and tell the function of each part of the digestive system Liver The 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.

34 Liver Not part of alimentary canal but plays a role in digestion. Connected to ileum by hepatic portal vein Decides whether to store or send nutrients to body cells Majority of fatty acids transported by Lacteals (lymphatic system which eventually connects back to blood vessels) 13/06/2014

35 Found under diaphragm overlapping stomach. Made up of lobes Rich blood supply from Hepatic portal :vein and artery Recieves mainly a.a. and glucose Excess glucose converted into glycogen here and reconverted and released when need by blood Excess a.a toxic, Altered to urea via process of Deamination

36 Urea (nitrogenous waste) is removed from liver sent to kidneys to be removed as urine 13/06/2014

37 To quiz yourself over the parts of the digestive system, go to website /science/sbi3a1/digest/digdiag. htm

38 Chemical digestion Chemical digestion also starts in the mouth and continues in the stomach and small intestines Chemical digestion occurs with the aid of enzymes, biological catalysts. FoodSimpler substance Carbohydrates, starch ( polysaccharides) Glucose, maltose, lactose PrtoeinsAmino acids Lipids ( fats)Fatty Acids and glycerol

39 ENZYMES Are proteins Specific to particular substrate; Induced fit, lock and key mechanism Required in small amounts, can be reused Work best at an optimum temp; fastest rate of rxn Work best at particular pH : optimum pH

40 ENZYMES Are inhibited or prevented from working by poisons like arsenic, cyanide Rxn occur quickly, each 10 degree temp rise, doubles rate of rxn Denatured at high temperatures, therefore enzyme structure is compromised no rxn occurs. Most enzymes work best around a neutral pH but 2.5, 13/06/2014

41 Enzymes Enzymes 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

42 Part of digestive system Food substance acted on Enzyme used and pH of environment products Mouth via saliva CarbohydratesAmylase ( ) pH Glucose Stomach acidic environs provided by HCl secreted from vesicles in stomach lining : acidic pH Proteins:Pepsin(acidic environ) pH2-3 Rennin Amino acids Liquid milk to solid Small intestines; doesnt produce enzymes they are all obtained from pancreatic juice Carbs, rest of proteins, fats Amylase sucrase, maltase, lactase, trypsin (pH ), lipase, peptidase Glucose, amino acids, Fatty acids and glycerol. 13/06/2014

43 DIGESTIVE SYSTEM ANIMATION:

44 13/06/2014 The small intestine This is where the small parts are absorbed into our blood stream… Glucose gets absorbed into the blood Everything else passes into the large intestine


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