The structures within the digestive system Copy

From the mouth there is a long muscular tube which goes to the anus. This is where digestion takes place. This involves food being taken into the mouth, broken down and then absorbed into the blood. The waste that is not required is then eliminated from the body.

digestive system presentation

The digestive system is composed of:

 Mouth

It is here that food is broken down by the teeth and mixed with saliva from the mouth.

Pharynx and oesophagus

The broken down food is pushed to the back of the mouth, and then the pharynx muscles push it down into the oesophagus. This is a long thin tube where the food is forced down into the stomach.

Peristalsis (contractions) takes place which breaks the food down further and moves it down towards the stomach.

Stomach

This is a muscular organ situated on the left side of the abdomen below the diaphragm. It is here the food is broken down further, as it mixes with gastric juices and proteins which help to digest it.

Food can stay in the stomach for up to five hours until it becomes a liquid (chyme). It is then released at different times, into the small intestine.

Small intestine

This consists of the duodenum, jejunum and the ileum. Peristalsis continues here as the food continues to be broken down further by several juices. These are:

Bile

This is stored in the gall bladder and is used to break up fat droplets (emulsification), and neutralise the chyme.

Pancreatic juice

This is produced in the pancreas. It excretes enzymes which continue to digest the fats, carbohydrates and proteins.

Intestinal juice

This is released by the small intestine and finalises the complete breakdown of all the nutrients.

The main feature of the small intestine is the thousands of minute villi, that are present which pass the digested food into blood stream.

The large intestine

This consists of the ascending, transverse and the descending colon, which are wrapped around the small intestine.

The functions of the large intestine are:

• Absorption of water from the waste. Bacteria and food that is not digested is made into waste
• The storage of waste
• The elimination of waste through the anus to outside of the body