S c i e n c e

DIGESTION YEAR 8 TOPIC ONE

Year 8 Exam Revision PageDigestion:The seven food groups are carbohydrates, protein, fats, vitamins, minerals, fibre and water.Biuret - is used to test for protein, if protein is presented then it will turn purple.Iodine - is used to test for starch, if starch is present it will be blue - black.Benedict - is used to test for glucose, if present it will turn orange/red.Ethanol - is used to test for fat, if present it will turn cloudy white. There are two types of digestion, mechanical / physical digestion, which is digestion that involves teeth and chemical digestion is using chemicals like enzymes.The 3 enzymes are called amylase, protease and lipase. The amylase breaks down starch, protease breaks down protein and lipase breaks down fats/ lipids.

Parts Of The Digestive SystemMouth - is the beginning of the digestive system, where starch is broken down by amylase in saliva which contains mucus and amylase.Salivary glands - is where the saliva comes from.Oesophagus - is the pipe that food uses to go through.Stomach - contains stomach acid which will desolve the food substances.Gallbladder - stores bile from the liver, the bile is an alkali that neutralizes acids and breaks fat.Liver - makes the bile and breaks down amino acids and converts glucose to glycogen.Pancreas - makes the 3 enzymes amylase, protease and lipase.Duodenum - is the starting of the small intestine where the chemicals are mixed.Ileum - is the end of the small intestine, which contains the villi which puts the protein, vitamins and minerals into the blood stream.Jejunum - is part of the small intestine that absorbs nutrients and also has a micro villi.Colon - Absorbs water and digests fats.

Respiration - the process that oxygen to free energy from food making carbon dioxide in the process. When oxygen mixes with glucose it creates carbon dioxide and water.

The Circulatory System - travels substances around the body. Blood flows away from the heart in arteries and back to the hearts carrying oxygen in the viens. the right side of the heart pumps deoxygenated blood to the lungs. There are red blood cells, white blood cells, platelets and plasma.