Digestive System

• Muscle cells can contract. They contain special protein fibres which can change their length
• Muscle cells are packed full of mitochondria to provide energy for contraction
• A tissue is a group of cells with a similar structure and function
• An organ is a group of tissues working together for a specific function. (E.g. the stomach which contains muscle and glandular tissue)
• Organs are grouped into organ systems which work together to form organisms
• Food contains three main nutrients, carbohydrates, protein and lipids
• Proteins, Carbs and Lipids are large molecules. They are too large to be absorbed so they have to be digested.
• Large food molecules are broken down into small molecules by enzymes. They are then absorbed into the bloodstream.
• The liver releases bile which helps to speed up the digestion of lipids. Bile also neutralises the acid released from the stomach.
• The pancreas releases enzymes which continues the digestion of starch and protein. They also start the digestion of lipids.
• Small molecules produced by digestion are absorbed into the bloodstream either by diffusion or active transport.