Organisation

• Multicellular organisms are made up of organ systems
• Similar cells are organised into tissues such as muscular, glandular and epithelial
• Tissues are organised into organs
• Muscular tissue makes up the stomach walls
• Glandular tissues make digestive juices
• Epithelial tissue cover the inside and outside of the stomach
• Enzymes are biological catalysts
• Enzymes have special shapes so they can catalyse reactions
• Each enzyme has an active site which fits the substrate.
• The lock and key model is used for enzyme action
• Enzymes need the correct temperature and pH to work effectively
• When it gets too hot or the pH is too high or low, the enzyme denatures
• Pepsin works best at pH 2
• Amylase breaks down starch and is produced in the salivary glands, small intestine and pancreas
• Protease breaks down protein into amino acids and is produced in the stomach, pancreas and small intestine
• Lipase breaks down lipids into fatty acids and glycerol and is produced in the pancreas and small intestine
• Bile emulsifies fat and neutralises stomach acid
• Bile is stored in gall bladder and released into small intestine
• Large intestine absorbs excess water from food
• Small intestine is where digested food is absorbed into the body
• Hydrochloric acid is produced in the stomach to kill bacteria and provide the right pH for pepsin to work
• Benedict's is used for testing for reducing sugars and should be used in a water bath at 70 degrees
• Benedict's colour change = Blue to Green to Yellow to Red
• Iodine solution is used to test for starch
• Iodine colour change = Brown/Orange to Blue-Black
• Biuret's reagent is used to test for proteins
• Biuret colour change = Blue to Lilac
• Ethanol and Water solution is used to test for fats
• Ethanol colour change = Colourless to cloudy
• Lungs are in the thorax
• The air is breathed in through the trachea and then to the Bronchi then the bronchioles and finally the alveoli
• Alveoli carry out gas exchange in the lungs
• Alveoli are surrounded by capillaries which allow for the exchange of gases into the bloodstream
• Humans have a double circulatory system
• The left ventricle pumps blood to the body
• The right ventricle pumps blood to the lungs
• Veins have valves to prevent blood flowing in the wrong direction
• The pulmonary artery is the only artery that does not carry oxygenated blood
• Coronary arteries surround the heart and supply it with oxygenated blood
• The Vena Cava carries deoxygenated blood from the body to the heart.