The Digestive System
The Digestive System
Digestion is important for breaking down food into nutrients, which the body uses for energy, growth, and cell repair. Food and drink must be changed into smaller molecules of nutrients before the blood absorbs them and carries them to cells throughout the body.
The main organs of the human digestive system form a tube that runs from the mouth to the anus. These function to ingest and digest food, absorb nutrients and remove undigested waste. Organs such as the liver, gall bladder and pancreas are also involved as they secrete enzymes and bile which aid in the digestion of food.
Digestion
A short video to watch covering the Digestive system.
Mechanical Digestion
- Mechanical digestion involves physically breaking down food substances into smaller particles to more efficiently undergo chemical digestion.
Teeth
Teeth are needed for mechanical digestion of food. There are 4 main groups of teeth in mammals
Incisors - biting teeth 'cutting'
Canine - holding and tearing
Pre-Molar - tearing and crushing
Molar - tearing, grinding and crushing
Structure of a Tooth
Teeth all have a similar structure. Enamel covers the crown of the tooth and is the hardest tissue in the body. It is reinforced by the dentin underneath which in turn protects the dental pulp consisting of the nerve and blood supply.
Chemical Digestion
Enzymes
Enzymes are proteins that function as biological catalysts. They are molecules that speed up a chemical reaction without being changed by the reaction. Enzymes are highly specific. Each type of enzyme is usually only able to catalyse only one type of reaction (some may catalyse a few types of reactions).
Digestive Enzymes
Carbohydrase enzymes such as amylase digest carbohydrates, pepsin is an example of a protease enzyme that digests protein, while lipase is an enzyme involved in the digestion of fats(lipases)
Digestive System Enzymes
Enzymes act on specific substrates and are very sensitive to the temperature and pH of the environment. This is why there are many different enzymes involved in food digestion as the environment of the digestive system changes.
The Stomach
The stomach is like a mixer, churning and mashing together all the small balls of food that came down the esophagus into smaller and smaller pieces. In addition to breaking down food, gastric juices also help kill bacteria that might be in the eaten food.
The Liver, Gall Bladder and Pancreas.
The Liver, Gall Bladder and Pancreas are glands which secrete substances that aid in the digestion of foods. These are secreted into the duodenum(first section) of the small intestines.