- Created by: MicaiahDollery
- Created on: 28-01-20 19:48
B3.1 tissues and organs
- A tissue is a group of cells with similar structure and function.
- Organs are made up of tissues.
- Organs are organised into an organ system witch work together to create an organism.
- Organ systems include the digestive system , circulatory system and gas exchange system.
- These systems have specialized organs in them so they can do thir job correctly and its more efficient.
- Muscular tissue, can contract to bring about movment
- glandular tissue, to produce substances such as enzymes or hormons
- Epithelial tissue, covers some parts of the body.
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B3.2 The human digestive system
- Organ systems are groups of organs that preform specific functions in the body.
- The digestive system in a mammal is an organ system in which several organisms work together to digest and absorb food.
- Glands,such as the pancreas and salivat glands produce digestive juices containing enzymes.
Human digestive system;
- stomach-where digestion occurs
- liver-produces bile
- small intestine-digestion occurs
- large intesting-water is absorbedfrom undigested food
- pancres-produce digestive juices
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B3.3 The chemistry of food
- Carbohydratesare made up of units of sugar.
- Simple sugars are carbohydrates only one of two sugar units they turn blue Benedicts solution turn brick red on heating.
- Complex carbohydrates contain long chains of simple sugar units bonded together. Starch turns yellow-red iodine solution blue-black.
- LIpids consist of three molecules of fatty acids bonded to to a molecule of glycerol. A cloudy white layer with the ethanol test inicates the presence of lipids in solutions.
- Proteinmolecules are mode up of long chains of amino acids. Biuret reagent turns from blue to purple in the presents of protein.
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B3.4 Catalysts and enzymes
- catalysts increase the rate of chemical reaction withouth changing themselfs.
- Enzynes are biological catalysts. The catalyst specif reactions reactions in living organisms due to the shape of thier active site. This is the lock and key theory of enzymes reactions.
- The substrate binds to the active site and the reaction is catalyst by the enzyme.
- Metabolism is the sum of all the reaction in a cell or in the body.
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B3.5 Factors affecting enzyme action
- Enzyme activity is affected by temperature and pH.
- High temperature denatures the enzyme, changing the shape of the active site.
- pH can also affect the shape of the active site of an enztme and make it work very effeciently or stop it from working.
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B3.6 How the digestive system works
- Digestion involves the break down of large,insoluble molecules into soluable substances. these smaller molecules can then be absorbed into the blood across the wall of the small intestine.
- Digestive enzymes are produced by specialised cells in glands and in the linning of the digestive system.
- Carbohydrates such as amylase, catalyse the break downs of carbohydrates into simple sugars,
- Protease catalyse the breakdown of proteins to amino acids.
- Lipases catalyse the break down of lipids to fatty acids and glycerol.
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B3.7 Making digestion efficient
- The protease enzymes of the stomach work best in acid conditions. The stomach produces hydrochloric acid which maintains a low pH.
- The enzymes made in the pancreas and the small intestine work best in alkaline conditions.
- Bile is produced in the liver , stored in the gall bladderand released through the bile duct . It nuetralises and emulsifies fats.
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