Most of the food we eat is fuel, burned by our body for energy to keep us going. It gets this mainly from substances in food called Carbohydrates and fats. But we also need to eat small amounts of food such as proteins to help repair and build body cells and tiny traces of chemicals called vitamins and minerals the body cannot make itself.
Our food goes down through our body in a long tube called the alimentary canal. When we swallow, food slides down our gullet or esphagus into the stomach, where it churns around for few hours. Then it is squeezed into a long, coiled tube called the small intestine where nourshing parts of the food are absorbed into the blood. The rest then passes on into a larger tube called the large intestine, and the waste or faeces is pushed out through the anus. Our guts or intestine are so coiled that if we unwound them, they would be more than three times as long as our body.
Digestion Process
Food is broken into the small molecules the body needs by a process called digestion in two ways. First, food is broken up mechanically by chewing and by the squeezing muscles of our gut. Second, it is attacked chemically by acids, such as the bile and hydrocholoric acid in our stomach, and by biological chemicals called enzymes, mixed in with our saliva and stomach juices.
Carbohydrates :
Carbohydrates are foods made of kinds of sugar like glucose and starch. Food such as bread, rice, potatoes, and pasta, as well as sweet things, are rich in carbohydrates.
Fat : Fats are greasy foods that won’t dissolve in water. Some are solid, like cheese and meat fat. Others are oils. Fats are usually stored by the body as energy reserves, rather than burned up at once like carbohydrates.
A healthy diet contains just the right amount of each kind of food our body needs, and no more. The bulk of our diet must be solid food like carbohydrates, but it must also contain enough fat, plenty of protein, and the right vitamins and minerals.
Proteins :
To grow, our body needs proteins, the natural substances from which cells are built. Proteins are made from 20 basic chemicals called “amino acids”. The body can make 12 of these. The other eight we must get by eating protein – rich food such as milk, fish, meat, eggs, and beans.
Different types of teeth :
Different teeth do different jobs. The flat “incisors” at the front have sharp edges for slicing through food. The pointed “canine” teeth just behind are good for ripping chewy food. The big flat – topped “premolars” and “molars” toward the back of our mouth are good for grinding food into a small, mushy ball ready to be swallowed.
