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A Three Part Story!

The small intestine is made up of three parts, the Duodenum, the Jejunum and the Ileum.

Duodenum, Jejunum and Ileum

The first part of the small intestine is called the duodenum. The acidic chyme that is leaving the stomach would damage the lining, so to make it safe it is neutralised by an alkali (similar to how Tanno and Iguda escaped the stomach acid). The duodenum also receive enzymes from the pancreas that continue to digest the food chemicals, as well as the liver producing bile, which is important in helping fat digestion.

The food then moves through the jejunum and into the ileum, where digestion is completed by even more enzymes.

The digested food molecules are absorbed in the small intestine. This means that they pass through the wall of the small intestine and into our bloodstream. Once there, the digested food molecules are carried around the body to where they are needed.

Image credit: Anatomical models by Somso, image courtesy of Adam, Rouilly Ltd.

Microscopic Villi

The villi (a single one is called a villus) stick out and provide a big surface area. They also contain blood capillaries to quickly carry away the absorbed food molecules.

Efficient absorption across a surface happens when the surface is thin and its area is large. The inner wall of the small intestine is adapted so that substances pass across it quickly by having a thin wall which is only one cell thick, and many microscopic villi to give a really big surface area. This means all the useful digested food is absorbed into the blood.

Only small, soluble substances can pass across the wall of the small intestine. Large insoluble substances cannot pass through, which explains why digestion has to happen in the first place.

Images credit: Derek Aspinall; Anatomical models by Somso, image courtesy of Adam,Rouilly Ltd.

Lets take a journey ...

Learn about the entire digestive system from this video:

YOUR MISSION, SHOULD YOU CHOOSE TO ACCEPT IT …

YOUR MISSION, SHOULD YOU CHOOSE TO ACCEPT IT …

YOUR MISSION, SHOULD YOU CHOOSE TO ACCEPT IT …

YOUR MISSION, SHOULD YOU CHOOSE TO ACCEPT IT …

Investigating Enzymes

WARNING: some people are allergic to biological washing powder – do NOT do this activity if you are allergic.

 

Photo by Ron Lach on Pexels.com

Your Task

  • Take 3 glasses or clean empty jam jars and fill them with water.
  • Add 2 tablespoons of biological washing powder to one, 2 tablespoons of a different brand of biological washing powder to another, and leave the third as a control with just water.
  • Cut (with the help of an adult) the white of a hard-boiled egg into 3 lumps of about the same size or thickness, approximately 5mm thick.
  • Place 1 lump into each of the glasses / jars and leave somewhere warm for 3 or 4 days. Compare the appearance of the lumps.
  • Allow the experiment to run for longer if you want to see bigger differences.

Biological washing powder contains enzymes that are used to digest food stains on clothes, making them easier to clean. The egg white is made up of proteins so will be broken up by a washing powder with enzymes to break up proteins. Not all washing powders use the same enzyme and different brands may add different amounts of enzyme, so they don’t all work as well as one another.

You could extend this investigation by using a non-biological washing powder as well, just to check that it is the enzymes that affect the egg white and not some other ingredient.

– MISSION TWO INCOMING –

– MISSION TWO INCOMING –

– MISSION TWO INCOMING –

– MISSION TWO INCOMING –

Make a Small Intestine Model!

You could use an old sock and fill it with newspapers or old packaging or whatever you can find.

– MISSION END –

– MISSION END –

– MISSION END –

– MISSION END –

Your Journey So Far …

Tanno and Iguda have explored these places up to now. You can go back and visit again by clicking below.

Mouth

Stomach

Small Intestine

Great to see you here, thank you for the visit! See you next time …

Tanno & Iguda