Digestion and Nutrition : Biology
Learning targets : To make sure that I am eating a balanced diet and knowing the digestive system.
What makes up the digestive system and what is the function?
The mouth, the gullet, the stomach, the small intestine, the large intestine, the rectum and the anus that makes up the alimentary canal. The organs that are joined to it are the salivary glands, the pancreas, the liver and the gall bladder. They are also part of the digestive system.
The function is to break down food into simpler substances to be absorbed into the bloodstream and dispose the undigested food.
How is food processed and broken down and used by the body?
First, food enters the mouth. The teeth then chews the food into smaller pieces and the saliva help to kill the bacteria and bind the chewed food together into a slippery mass for sliding through the gullet. The saliva also makes the food moist and easier to chew and swallow. In the mouth, salivary glands excrete saliva which has amylase, an enzyme that breaks down starch into maltose.
The gullet then pushes the food down into the stomach.
The stomach is a muscular bag that can expand to contain the food. Food will be churned with hydrochloric acids and protease enzyme for several hours until it becomes a semi-liquid mush before pushing the food into the small intestine.
At the small intestine, food is being digested even further and absorbed the digested food into the bloodstream. Most of the digestion takes place here. Digestive juices (enzymes) are then secreted from the pancreas into the small intestine to help in the digestion of carbohydrates, proteins and fats. Maltase enzyme digest maltose into glucose, protease enzyme digest proteins into amino acids and lipase enzyme digest fats globules into fatty acids and glycerol. A greenish liquid called bile produces by the liver and stores in the gall bladder, it is then released into the small intestine to help to digest fats into fat globules.
At the large intestine, undigested food enters here where water and mineral salts are absorbed, leaving behind a semi-solid waste known as faeces.
The faeces are stored at the rectum until they are pass out from the body through the anus.
What makes up a nutritional and healthy diet ?
The Healthy Diet Pyramid :
Fats, oil, salt and sugar:
Main nutrients: Fats, carbohydrates and sodium.
Main function (fats and sugars): Provide energy.
Main function (salt): Maintain fluid balance.
Meat and alternatives:
Main nutrients: Proteins, fats, vitamin B, calcium, iron and zinc.
Main function: Help in growth and repair of our bodies.
Fruits and vegetables:
Main nutrients: Vitamins and minerals.
Main function: Help us fight against diseases and germs.
Rice and alternatives:
Main nutrients: carbohydrates, proteins and vitamin B.
Main function: Give us energy to do work like walking and playing, and for basic functions like breathing.
What is the importance of a nutritional and healthy diet ?
A healthy diet consists of little fats, sugar and salts, more meat and alternatives, more fruits and vegetables, and a lot of rice and alternatives. If we eat too much fats, sugars and salts, we will put on weight and have more chances of getting heart diseases. If we do not eat enough meat and alternatives, we will have less growth. If we do not eat enough fruits and vegetables, we will get sick easily because they helps us fight against diseases and germs as well as prevent constipation. If we eat too little rice and alternatives, we may feel tired easily because they give us energy. So, we need to have a nutritional and healthy diet to stay healthy.
