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Explain the Function of the Organs of the Digestive System

In this worksheet, students will explain the function of the organs that form the digestive system.

Worksheet Overview

QUESTION 1 of 10

Did you know that your small intestines are about 7 metres long?! And your large intestine is about 1.5 metres long! The intestines form part of our digestive system. The digestive system is an example of an organ system.  You can see some of the different systems in the picture below:

 

Image of different body systems

 

Cells are the basic building blocks of all living organisms. They come in different sizes and shapes. Some organisms are made of just one cell and are called unicellular, other organisms are multicellular – they are made up of many types of cells. Cells work together to carry out different life processes like digestion, which are needed for an organism to stay alive.

Each specific cell is grouped with other cells, similar in structure and function, to form tissues. Groups of tissues work together to form organs that have specific functions. Organs are organised into organ systems, which work together to form organisms

 

 

Image of plant cell to organism

 

 

In the above diagram, the first image shows a leaf cell. The leaf cells group together to form a tissue, the tissues work together to form an organ -  the leaf. The leaf and other organ systems work together to form the plant (an organism).

Organisation of the body allows complex organisms to carry out many different jobs at the same time.

 

The delicious burger and chips you ate for lunch have to be broken down in order for your body to use it. This breaking down of food is called digestion. The different organs that help with digestion are called the digestive system.  

 

Image of the digestive system

 

While chewing our food into smaller pieces, our food mixes in with our saliva. You wouldn’t think it, but our saliva is pretty special! Special because it makes your food moist and easy to swallow, but also it contains something called enzymes that help to break our food down.   

Your burger and chips are now mashed up and swallowed. This moves down through the oesophagus (the pipe connecting your mouth to your stomach). The oesophagus has muscles that contract in a wave-like motion, which helps to push the food along and into your stomach.

In the stomach, the food is churned up, breaking it down even more. Here it mixes with a strong acid of pH 1 - 2. The acid is so strong that it's able to destroy microbes that might be present in the burger and chips you ate.

From the stomach, food enters the small intestine and the small digested food molecules are absorbed into the bloodstream. Sugars like glucose, and also vitamins and minerals, are soluble in water, so can pass through the wall of the small intestine. Larger insoluble molecules like starch, proteins and fats need to be broken up into smaller molecules by enzymes before they can be absorbed. Certain foods such as fibre we can’t digest. 

The liver also helps with digestion. The liver makes a substance called bile which is released into the small intestine. The bile helps to cancel out (neutralise) stomach acid before it enters the small intestine. Bile also helps to break up fat into smaller droplets, allowing it to be digested quicker.

After the small intestine, the remains of the food travels to the large intestine. All that is left of the burger and chips now is water and waste material.

The water is valuable, so it’s absorbed from the large intestine into the bloodstream. The kidneys also help to make sure we have the right amount of water in our body.

The waste material can’t be digested or used by the body. The undigested waste travels to the rectum, where it is stored until leaving the body through the anus as faeces. Lovely!

 

In the following activity, you will explain the function of the different organs that make up the digestive system.

 

Cells are the basic building blocks of all living organisms.

 

Link the different groups to their definitions.

 

 

Image of plant cell to organism

Column A

Column B

Cell
Cells grouped with other cells similar in structur...
Tissue
Building blocks of all living organisms
Organ
Groups of organs which work together to form organ...
Organ System
Groups of tissues working together with specific f...

The oesophagus has an important role to play in digestion.

 

Explain how the oesophagus functions.

 

Image of the digestive system

To break food into smaller pieces

Muscles contract allowing food to be moved to the stomach

To allow nutrients to be absorbed

In the small intestine, certain food substances need to be broken down by enzymes.

 

Why?

 

To break food into smaller pieces

Muscles contract allowing food to be moved to the stomach

To allow nutrients to be absorbed

What is the job of the acid found in the stomach?

 

Image of the stomach digesting food

 

To break food into smaller pieces

Muscles contract allowing food to be moved to the stomach

To allow nutrients to be absorbed

The image below shows the organs that belong to the digestive system.

 

Explain the function of F in the image below.

 

Image of the digestive system

F is the anus where faeces are expelled

F is the rectum where waste is stored

F is the small intestine where food molecules get absorbed

Small digested molecules get absorbed into the bloodstream where they will be used by different parts of the body.

 

What happens to the undigested food?

 

Image of the digestive system

F is the anus where faeces are expelled

F is the rectum where waste is stored

F is the small intestine where food molecules get absorbed

 Are the following statements true or false?

The liver produces an important substance called bile.

 

Explain the function of bile in the digestive system. 

Bile is acidic and destroys microbes

Bile neutralises stomach acid

Bile breaks up glucose

Bile breaks up fat into droplets

In digestion, which organ produces the bile needed for breaking fats into smaller droplets?

Large intestine

Stomach

Liver

Small intestine

Explain the function of A in the picture below.

 

Image of the digestive system

The oesophagus connects the mouth to the stomach

The mouth chews up the food into smaller pieces and mixes it with saliva, making it easier to swallow

The liver produces bile neutralising stomach acid

  • Question 1

Cells are the basic building blocks of all living organisms.

 

Link the different groups to their definitions.

 

 

Image of plant cell to organism

CORRECT ANSWER

Column A

Column B

Cell
Building blocks of all living org...
Tissue
Cells grouped with other cells si...
Organ
Groups of tissues working togethe...
Organ System
Groups of organs which work toget...
EDDIE SAYS
How did you find this first question? This is pretty basic stuff, so it is important that you try to remember the following: Cell → Tissue → Organ → Organ System Cells make up the tissues, tissues make up the organs, organs work together to make an organ system. And there you have it - an organism!
  • Question 2

The oesophagus has an important role to play in digestion.

 

Explain how the oesophagus functions.

 

Image of the digestive system

CORRECT ANSWER
Muscles contract allowing food to be moved to the stomach
EDDIE SAYS
The oesophagus is the tube that connects the mouth to the stomach, and its function is to help to get the food moved to the stomach easily. It is well adapted for this because the muscles in the oesophagus contract in a wave-like motion to help food move down to the stomach, where the next stage of digestion occurs.
  • Question 3

In the small intestine, certain food substances need to be broken down by enzymes.

 

Why?

 

CORRECT ANSWER
EDDIE SAYS
The whole purpose of digestion is to get the different nutrients out of food and into the cells of the body. To do this, it is necessary for molecules to be absorbed through the walls of the small intestine into the bloodstream. Large molecules can't be absorbed, which is why enzymes are so important. The enzymes will break the large molecules into smaller soluble molecules, which can then be absorbed into the blood and carried to all the cells of the body.
  • Question 4

What is the job of the acid found in the stomach?

 

Image of the stomach digesting food

 

CORRECT ANSWER
EDDIE SAYS
Hopefully, you came up with an acceptable word here - you were permitted microbes, pathogens, bacteria or microorganisms. The acid in the stomach is very strong. It has a pH of between 1 and 2. Luckily, we have a protective layer inside our stomachs to stop the acid from wearing our own stomach away!
  • Question 5

The image below shows the organs that belong to the digestive system.

 

Explain the function of F in the image below.

 

Image of the digestive system

CORRECT ANSWER
F is the rectum where waste is stored
EDDIE SAYS
Did you manage to identify all the different parts of the digestive system here? F is pointing to the rectum where waste is stored. G is the anus, from where faeces are removed, and D is the small intestine where food is absorbed into the bloodstream.
  • Question 6

Small digested molecules get absorbed into the bloodstream where they will be used by different parts of the body.

 

What happens to the undigested food?

 

Image of the digestive system

CORRECT ANSWER
EDDIE SAYS
Undigested food has no nutritional value as all the nutrients and useful molecules have been removed. Water is also reabsorbed from the large intestine, leaving only the waste that the body no longer needs.
  • Question 7

 Are the following statements true or false?

CORRECT ANSWER
EDDIE SAYS
How did you get on with this one? Did you make the mistake of ticking true for the one about the stomach acid? The stomach does indeed contain a strong acid, but it is there to kill any microbes that might be present on the food that has been consumed. The oesophagus takes food to the stomach, not to the large intestine. The small intestine is actually really long but is coiled up, so it fits into our body. The food molecules are small enough to pass through the folds of the small intestine. Watch out for little tricks like this one - some of the statement might be correct, but it is important to read through carefully to check that the whole thing is right.
  • Question 8

The liver produces an important substance called bile.

 

Explain the function of bile in the digestive system. 

CORRECT ANSWER
Bile neutralises stomach acid
Bile breaks up fat into droplets
EDDIE SAYS
There were two correct options here. Bile aids digestion but it doesn't contain enzymes. Instead, it breaks down fats into smaller droplets to help enzymes to digest them quicker. Bile also neutralises acidic food that has come from the stomach. This means that it can't possibly be acidic itself - in fact it is a strong alkaline substance, and it creates an alkaline environment which is perfect for the enzymes used in digestion.
  • Question 9

In digestion, which organ produces the bile needed for breaking fats into smaller droplets?

CORRECT ANSWER
Liver
EDDIE SAYS
The liver produces bile which speeds up the digestion of fats, breaking them down into smaller droplets. This gives a larger area for enzymes to work on, as well as creating an alkaline environment allowing the enzymes to work at their optimum level.
  • Question 10

Explain the function of A in the picture below.

 

Image of the digestive system

CORRECT ANSWER
The mouth chews up the food into smaller pieces and mixes it with saliva, making it easier to swallow
EDDIE SAYS
This might not be a very accurate image to show parts of the digestive system, but it isn't that hard to eliminate the other options once you read them! Label A is right at the top of the image, which is a clue to it being the mouth - it certainly can't be either the liver or the oesophagus! The first part of digestion happens in the mouth where food is chewed and broken down into smaller particles. The saliva is important too - don't forget that saliva contains enzymes. The enzymes in the saliva mix with the food to start the digestive process off. Another activity completed. Terrific !
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