The Digestive Journey
Trace food through the mouth, oesophagus, stomach, small intestine and large intestine. Explain chewing, saliva, stomach mixing and nutrient absorption, then follow leftover waste into the rectum and out through the anus.
What a learner can do afterwards
- Put the mouth, oesophagus, stomach, small intestine and large intestine in route order; explain that leftover waste enters the rectum and leaves through the anus
- Describe how teeth chew, saliva wets food and starts digestion, the oesophagus moves swallowed food, and the stomach churns and mixes food with digestive juices
- State that most nutrients are absorbed in the small intestine, while the large intestine absorbs water from leftovers and helps form more solid waste
1 · Read
Food gives your body nutrients for energy and growth. Digestion breaks food down so your body can use it. Follow these main parts in order: mouth, oesophagus, stomach, small intestine and large intestine. Leftover waste then enters the rectum and leaves through an opening called the anus.
Teeth chew food into smaller pieces. Saliva wets food and starts breaking down some of it. After you swallow, muscles push food down the oesophagus towards the stomach. The stomach churns food while mixing it with digestive juices, including acid. These actions help break food down into a thick mixture.
These boxes show how swallowed food moves towards the stomach.
Food next reaches the small intestine, where digestion continues and most nutrients are absorbed through the walls. Blood carries absorbed nutrients around your body. Leftovers reach the large intestine, which absorbs water from them. The waste becomes more solid, enters the rectum and leaves through the anus.
Digestion starts in the mouth. Most nutrients are absorbed in the small intestine. The large intestine absorbs water from leftovers. Waste leaves through the anus.
Lesson, questions and study cards written for this dataset.
Readings written for this dataset using supplied OpenStax and Khan Academy records for background facts. Referenced TED-Ed videos are credited to Emma Bryce and Shilpa Ravella.
More to read
A route with an exit
Make a route map for a bite of food. Begin with the mouth. Put the oesophagus between the mouth and stomach. After the stomach, add the small intestine and large intestine.
The route continues beyond those five names. Leftover waste enters the rectum before passing out through the anus. The large intestine is near the end of the route, but it is not the opening where waste leaves.
What happens before swallowing?
Think about a bite of bread. Your teeth bite and grind it into smaller pieces. Saliva makes the pieces wet and starts breaking down some of the starch in the bread.
Chewing and the action of saliva both happen in the mouth. Digestion has begun before the bite reaches your stomach. Once you swallow, muscles in the oesophagus push the food onward.
Mixing inside the stomach
The stomach receives food from the oesophagus. Its muscular walls move the food around, mixing it with digestive juices. Those juices include acid and substances that help break food down.
Churning and mixing happen together. Food becomes a thick mixture, then moves into the small intestine. Reaching the stomach does not mean digestion is finished.
Food changes and nutrients travel
Digestion and absorption are different jobs. Digestion breaks food down. Absorption moves nutrients through the walls of the digestive system into the body.
The small intestine is where most nutrients are absorbed. Blood carries absorbed nutrients to other parts of you. Your body uses nutrients for growth, repair and energy. The digestive system helps make nutrients available; your body then uses them.
The material left behind
Some material remains after food passes through the small intestine. It moves into the large intestine, where water is absorbed from it.
As water is taken out, the leftover waste becomes more solid. The waste enters the rectum and later leaves through the anus.
Keep these two jobs apart: most nutrient absorption happens in the small intestine, while the large intestine absorbs water from leftovers and helps form solid waste.
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