Food is composed of carbohydrates, proteins, fats, vitamins, minerals and water. Carbohydrates and fats provide energy. Proteins provide the building blocks for growth and repair. Vitamins and minerals are needed in small amounts and are important for a healthy body. A healthy, balanced diet, containing the right amounts of nutrients and water, is essential to wellbeing. An unhealthy diet, high in fatty or sugary processed foods, can lead to many health problems including obesity, type 2 diabetes and heart disease. The digestive system is a group of organs working together to break down food into simple molecules that can be absorbed into the bloodstream. The organs of the digestive system are the oesophagus, stomach, small intestine and large intestine. The salivary glands, liver and pancreas work with the digestive system to break down food. The five stages of nutrition are: ingestion, digestion, absorption, assimilation and egestion. Physical digestion involves the mechanical breakdown of food into smaller pieces. It occurs in the mouth and the stomach. Chemical digestion involves the use of chemicals called enzymes to break down food. An enzyme is a chemical made in a living cell which can speed up a chemical reaction, without itself being changed. Chemical digestion occurs in the mouth, stomach and small intestine. Absorption is when simple food molecules pass from the small intestine into the bloodstream.
Absorption occurs in the small intestine. The large intestine absorbs water and stores waste material for elimination. Egestion involves getting rid of waste through the anus. The digestive system and the circulatory system work together to provide the body with materials for energy, growth and repair.
