When you put food into your mouth, its starting a journey through your digestive system. It is a tube like structure, up to nine metres long running from the mouth to the anus.
saliva
When the sandwich is being chewed, it gets mixed with saliva. The saliva contains an enzyme which helps to break down the starches in the bread.
The teeth then grinds the sandwich into small pieces and mixes it with saliva, which is produced by the salivary glands.
oesophagus
After you swallow the sandwich, it enters the oesophagus which is also know as the gullet. The muscles in the oesophagus contract in order to push the sandwich towards the stomach.
Here, the sandwich is being churned and mixed with acid
As the sandwich travels down it arrives at the stomach. Here it is churned and mixed with stomach acids that have a pH of 1-2. They are very toxic and corrosive.
(gallbladder)
(liver)
Now, the bits of the sandwich will enter the small intestine where more digestive juices are added and the molecules of food are absorbed. A substance called bile that is stored in the gallbladder (from the liver) is also added, and this helps to digest lipids.
the water being absorbed from the sandwich
After the absorption in the small intestine, the undigested parts of the sandwich go into the large intestine. The large intestine then absorbs all the water from the sandwich.
egestion
After the parts of the sandwich has been passed down to the rectum, it will be pushed out from the anus in a process which is called egestion.
anus
The sandwich travelling down to the rectum