Digestive System: What Happens In The Small & Large Intestines?

Introduction

Have you ever wondered what happens to your food after you swallow it?

Your body’s digestive system works like a high-tech factory that breaks down food into simpler substances and absorbs digested food through the walls of the small intestine into the bloodstream.

And your small intestine and large intestine play vital roles in these processes.

But how do they work together? Keep on reading this P3 blog post on Digestive System to find out!

You can also watch my explainer video for free by visiting our YouTube channel.

Let’s Take A Look At This Digestive System Question

Source: Nan Hua Primary School – 2016 P3 SA2 Examination Paper [Q9]

In the diagram above, we have the small intestine and the large intestine.

Which system in our body do these two organs belong to?

They are part of our digestive system!

Thought Process

Let us start analysing the diagram by recalling the two processes that take place in the small intestine:

1️⃣ Digestion – It is the process where food is broken down into simpler substances. The small intestine carries out digestion by releasing digestive juices.

2️⃣ Absorption – The digested food will then be absorbed through the walls of the small intestine into the bloodstream.

Source: Nan Hua Primary School – 2016 P3 SA2 Examination Paper [Q9]

Which arrow, A or B, represents the absorption of digested food through the walls of the small intestine into the bloodstream?

It is arrow A!

So, material A must be the digested food.

Source: Nan Hua Primary School – 2016 P3 SA2 Examination Paper [Q9]

Digestion takes place in the small intestine.

But are all the food digested in the small intestine? No. There would be some undigested food left!

And where would this undigested food move to? The undigested food would move from the small intestine into the next organ, which is the large intestine!

So, material B represents undigested food.

Source: Nan Hua Primary School – 2016 P3 SA2 Examination Paper [Q9]

Let’s recall, what process takes place in the large intestine? It is absorption.

But what does the large intestine absorb?

It absorbs two materials from the undigested food into the bloodstream:

💧 Water
💪🏼 Mineral salts

If we were to draw another arrow, C, pointing from the large intestine to the blood, what would it represent?

Material C would represent water and mineral salts.

Source: Nan Hua Primary School – 2016 P3 SA2 Examination Paper [Q9]

Now, we know that material A represents digested food and material B represents undigested food so the answer to this question is option (2).

Correct Answer For Q9

Option (2)

Source: Nan Hua Primary School – 2016 P3 SA2 Examination Paper [Q9]

Conclusion

I hope that you found this Digestive System blog post informative.

Here are the 2 key takeaways from this blog post:

🔎 The small intestine breaks down food into simpler substances (digestion) and absorbs digested food through the walls of the small intestine into the bloodstream (absorption).
🔎 The undigested food moves to the large intestine, where absorption takes place. The large intestine absorbs water and mineral salts from the indigested food into the bloodstream.

Stay tuned for more blog posts on the Digestive System!