The Digestive System
The digestive system breaks food into small soluble molecules that can be absorbed into the blood.
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Play with the controls to see the idea in action.
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The digestive system breaks food into small soluble molecules that can be absorbed into the blood.
- Mouth, stomach, small intestine, large intestine
- Enzymes break down food chemically
- The small intestine absorbs nutrients
🧠 Quick quiz
Three questions. Score 2 or more to complete the topic.
What is The Digestive System?
Within Biology, which covers cells, the human body, genetics, evolution, plants and ecosystems: the science of living things, this topic explains The Digestive System. Biology topics show how living things work, from the cell up to whole ecosystems, with models you can explore step by step.
Check that you can explain The Digestive System in your own words and give one example from everyday life. If you can do that, you have understood the core idea.
Understanding The Digestive System helps you explain how living things stay alive and respond to their surroundings, which is central to biology exams.
The Digestive System in detail
The digestive system breaks down food into small, soluble molecules that can be absorbed into the blood. Food passes along the alimentary canal: mouth, oesophagus, stomach, small intestine, large intestine and rectum. Glands such as the salivary glands, pancreas and liver help with digestion.
In the mouth, teeth break food down mechanically and saliva starts digesting starch. The stomach churns food with acid and enzymes, the small intestine completes digestion and absorption, and the large intestine absorbs water. Peristalsis, waves of muscle contractions, moves food along. Undigested food is egested as faeces.
How the interactive helps you understand The Digestive System
Click a step, or use the Previous and Next buttons, to move through the sequence one stage at a time. Auto-play moves on for you.
Before you change anything, predict the result. Then change one value at a time and check whether your prediction was right. This is a quick way to build a correct mental model of The Digestive System.
Real-life uses and examples
- Explain how The Digestive System helps a living thing stay alive, using a plant or animal example.
- Connect The Digestive System to health, food and medicine in everyday life.
- Use The Digestive System to interpret a diagram, graph or microscope image from a practical.
Common mistakes to avoid
- Using everyday words, such as “energy” or “bad”, without their scientific meaning.
- Listing the steps of a process without saying how one step causes the next.
- Learning the definition without testing it. Use the quiz and the interactive to check that you can apply the idea.
Frequently asked questions about The Digestive System
What is The Digestive System?
The digestive system breaks food into small soluble molecules that can be absorbed into the blood.
What are the most important points about The Digestive System?
The main points are: Mouth, stomach, small intestine, large intestine; Enzymes break down food chemically; The small intestine absorbs nutrients.
Why is The Digestive System useful?
Understanding The Digestive System helps you explain how living things stay alive and respond to their surroundings, which is central to biology exams.
How can I practise The Digestive System?
Open the interactive at the top of this page and change the controls one at a time. Predict the result before each change, then take the three-question quiz. A score of two or more marks the topic as complete on this device.
Which topics are related to The Digestive System?
Related topics in Biology include Photosynthesis, Transport in Plants, Reproduction in Flowering Plants.