Biology - The Digestive System

First food enters the mouth, then the salivary gland produces amylase enzymes in the saliva catalyses the digestion of starch into sugars. Food then travels down the gullet (Oesophagus) Where it travels down to the stomach, the stomach pummels the food with its muscular walls, it produces the protease enzyme which breaks down protein into amino acids. It also produces hydrochloric acid for two reasons 1) to kill bacteria 2) To give the right PH for the protease to work (PH2). The Liver then produces Bile which neutralises stomach acids and emulsifies fats. It puts that in the tube before the small intestine, At the same time the Pancreas produces protease, amylase and lipase enzymes, The lipase enzyme breaks down lipids (fats and oils) to fatty acids and glycerol. The pancreas puts that into the tube before the small intestine. The food then travels through there and into the small intestine which produces protease, amylase and lipase enzymes to complete digestion, this is also where the food is absorbed out of the digestive system into the body. It then moves on to the large intestine where excess water is absorbed out of the digestive system into the body. Whats left gets passed to the rectum. This is where the faeces (made up of mainly indigestible food) are stored and prepares to leave the body through the anus.

Digestion involves the breakdown of large, insoluble molecules into smaller soluble molecules, we need to first digest are food so our body can absorb all the nutrients that it needs.

Amylase: Is produced by the salivary glands, the pancreas and the small intestines. Amylase catalyses the digestion of starch into sugars.

Protease: Is produced by the stomach, pancreas and small intestines catalyses the breakdown of protein into amino acids.

Lipase: Is produced by the Pancreas and the Small Intestine, Lipase catalyses the breakdown of lipids (fats and oils) to fatty acids and glycerol

The breakdown of food is catalysed by enzymes. 

A healthy diet is made up from the right balance of the different foods that you need.

You are malnourished if you don't have a balanced diet. If you take in more energy than you need you may become overweight or obese. This may result in health problems such as arthritis, Diabetes, High blood pressure and heart disease. 

However eating too little food can leave you being underweight, They might suffer from reduced resistance to infection, muscle wastage and irregular periods in women.

Fast Food

 Fast food is food that has already been prepared. It often contains too much fat and salt. Too much salt can lead too increased blood pressure.