9: Digestive system

digestive system

A group of organs that work together to break down food.

State what happens during digestion.

* Large molecules broken down into small molecules of nutrients
* Nutrients can pass into blood and be used by body

Describe the process of digestion.

1. Food chewed and mixed with saliva in **mouth**. Teeth help break food into smaller chunks.
2. Food passes through **gullet**.
3. Food mixed with digestive juices and acids in **stomach**.
4. In **small intestine**, digestive juices from liver and pancreas added - digestion is complete. Small molecules of nutrients pass through intestine wall into bloodstream.
5. In **large intestine**, only food that cannot be digested gets this far. Water passes back into body, leaving solid waste of digestive food called faeces.
6. Faeces are stored in **rectum** until they leave body.
7. Faeces pass out of the body through muscular ring called **anus**.

Describe the adaptations of the small intestine to its function.

The small intestine has a thin wall large surface area due to villi and the villi are only one cell thick as it enables a shorter diffusion path for nutrients, and blood capillaries to carry away any nutrients absorbed.

What happens to the small molecules on nutrients produced during digestion?

* Pass into bloodstream through small intestine’s wall
* Transported around body