What is the Digestive System?

• In order to function, the cells in our bodies need protein, carbohydrates, fats, vitamins, minerals and other nutrients that can be found in the food we eat.

• Before our organs and cells can absorb the nutrients and energy in food, it first has to pass through our digestive system.

Purpose of the Digestive System

• The digestive system is responsible for breaking down the food that we eat into smaller particles that can be absorbed into the bloodstream and used for energy, growth and nourishment.

• The particles are then transported to the cells and organs throughout our body.

The digestive system is made up of the different parts of the alimentary canal:

• This canal is a long, twisting pipe-like structure (9 metres) that starts at the mouth and ends at the anus.

• Along the way the food is broken down from chunks into molecules small enough to pass through cell membranes and supply energy to cells.

DID YOU KNOW?

Our digestive systems start working before food has even entered our mouths – by smelling or anticipating the first bite of food, we start salivating and our digestive system is activated!

The 4 Main Processes in the Digestive System

1.

2.

Ingestion: This happens when you take food or fluids into your body through your mouth by drinking or eating it.

Digestion: This is the process of breaking large food pieces down and processing fluids into particles that are small enough to be absorbed and pass through cell membranes.

3.

Absorption: When the digested particles move into the cells of the digestive tract and move to the bloodstream from where they are carried to all the cells in the body.

4.

Egestion: Any undigested or unwanted particles that travel through the digestive tract are later passed out as faeces.

Components of the Digestive System

1. The mouth and esophagus

Digestion starts in the mouth where food is chewed and mixed with saliva.

Saliva not only moistens the food before we swallow it; it also contains enzymes that break down carbohydrates (starches and sugars) before the food even leaves our mouths.

Food then travels down the oesophagus when you swallow.

DID YOU KNOW?

A soft ‘flap’ of tissue called the epiglottis closes over the windpipe when we swallow to prevent choking.

2. Stomach

The chewed food enters the stomach and is digested further through the churning of the stomach muscles and juices such as enzymes and acids that help digest the food. The stomach breaks the food down further into a more liquid state.

DID YOU KNOW?

In order for food to stay in the stomach while being digested, a valve-like muscle called a sphincter located at the end of the oesophagus squeezes itself shut.

3. Small intestine

Most of the digestion takes place in the small intestine. Absorption of the food particles takes place in the small intestine.

DID YOU KNOW?

Our small intestines contain tiny finger-like projections called villi that act as vehicles to transport nutrients into the blood that then circulates through the rest of the body.

4. Large intestine/colon

When the food reaches the large intestine, most of the nutrients have been absorbed into the bloodstream. The body then removes water from the undigested particles in order to form solid waste that is then excreted through faeces. The water that is left is absorbed in the large intestine.

DID YOU KNOW?

Your large intestine is about 1.82 metres long.

5. Rectum and anus

The remaining substances (faeces) are passed into the rectum where it is stored until the body is ready to pass it through the anus in the form of a bowel movement. This is also called egestion.

DID YOU KNOW?

Diarrhoea happens when waste passes through your large intestine too quickly.