Lesson video

Hi everyone.

My name is Miss Hummel and together we'll be answering the question, "How do humans digest food?".

In this lesson, we will learn about the digestive system.

We will learn about the different stages, including what happens in the mouth, the stomach, and the intestines.

We will also watch a demonstration and be able to explain the digestive system in our own words.

Our lesson will follow this structure.

First, we will discuss what the digestive system is.

Then we will discuss the role of the mouth.

We will move on to examining the role that the stomach plays.

And finally, we will discuss what our small and large intestines do, followed by a demonstration.

In this lesson, you will need an exercise book or paper, a pencil or pen, a coloured pencil or pen, and a ruler.

If you haven't got those things, pause the video now and go get them.

Here are our star words, which are the most important words of our lesson.

I'm going to say them and ask you to repeat them after me.

When I point at myself, it will be my turn.

When I point at you, it will be your turn.

Mouth.

Digestive.

Saliva.

Oesophagus.

Acid.

Stomach.

Enzymes.

Small intestine.

Large intestine Faeces.

And that's it.

We will begin by discussing what we mean when we say the words, digestive system.

Digestion refers to the fact that the food that we eat has to be broken down into other substances that our bodies can use.

Digestion occurs in the digestive system.

The digestive system involves a group of organs that help us get nutrients from food to fuel our bodies.

It also gets rid of waste.

So the digestive system involves a group of organs that helps us get nutrients from food to fuel our bodies.

It also gets rid of waste.

Now you have a go at saying it.

I would now like you to think about this, what organs can you think of which will be involved in the digestive system? Pause the video to answer the question and you can resume once you finished.

One of them is the mouth.

So let's take a look at where our digestive system begins.

The food enters the digestive system through the mouth.

We chew to break down our food into smaller pieces.

Now in the case of this photo, do you think that boy will need to do much chewing? Why or why not? You should have said that he probably won't do much chewing because what he's eaten doesn't necessarily need to be broken down into smaller pieces as it's already very soft and easy to kind of chew.

The teeth crush and cut the food and it's mixed with saliva.

This helps to make it softer and easier to swallow.

Have you ever noticed how something that is dry is harder to swallow than something that's very soft and maybe more liquid? After swallowing, the food travels down through the Oesophagus, which is a long tube connecting our mouth and our stomach.

I would like you to answer these questions now.

First, why do we chew our food? Second, how does saliva play a role in our digestive system? What is the name for the tube that our food goes down in after swallowing? You can pause the video to answer the questions and you can resume once you've finished.

You should have said that we chew our food because it makes it easier to swallow.

That saliva plays a role because it mixes in with our food and it makes it softer and again easier to swallow, that the name of the tube is Oesophagus.

Next, we're going to focus on the stomach.

The food enters the stomach.

After going through the Oesophagus.

You can see here in the diagram, how it's going through the Oesophagus onto the stomach.

In the stomach it's met with something called stomach acid.

The stomach produces strong acid.

This kills many harmful microorganisms that might've been swallowed along with the food.

So we might've swallowed something with our food that could make us ill, but our stomach has some strong acids that are trying to combat that.

And the acid is also helping break it down.

Within that, we've got something called Enzymes.

Now enzymes are the chemicals that break down food so that it can be absorbed.

So it's breaking it into things like nutrients and waste.

Now, what are enzymes? Great.

Next we've got our stomach muscles.

They move around and they help the food continue to digest by mixing and breaking it.

Here are some questions for you to answer.

First, what is the function of stomach acid? Second, what two things do enzymes help break down food into? And three, stomach muscles aid digestion by doing what? Pause the video and you can resume once you finished.

You should have said that the function of stomach acid is to protect our body from harmful microorganisms that could have entered our body with our food and also they help break down the food.

The two things that the enzymes help break down food into are waste and nutrients and the stomach muscles aid digestion by contracting and moving the food around which further breaks it down.

Finally, we're going to discuss the role of intestines.

The intestines are divided into small intestine and large intestine.

Now, do you know which one is which in the diagram? Let's start off with the small intestine.

The small intestine is where digested food is absorbed.

Nutrients pass through the wall of the small intestine and into the bloodstream.

The blood then carries the useful substances around the body to where they are needed.

Let's discuss the large intestine.

Now, most of the digestive food has been absorbed in the small intestine and what is left is waste material that the body doesn't need, or it can't digest.

This is called faeces or poo, which we get rid of through the anus when we go to the toilet.

For this activity, you should number the steps of the digestive system.

Number one has been done for you.

The top one says stomach crushes food and uses acid to break down food.

Chewed food travels down oesophagus to stomach.

The one that was labelled already was that food is chewed in mouth.

Then we've got food travels to the small intestine where nutrients are absorbed into the body.

We've got any undigested food passes out of the body as faeces when we go to the toilet, and we've also got food passes into the large intestine where more nutrients and water are absorbed.

So they're all jumbled up.

It's your turn now to put them in the right order, by numbering them.

Pause the video now to complete that, you can resume once you finished.

Now, you're going to watch a little demonstration of how the digestive system works in action.

But before you do, can you label the stomach in the diagram? So point at it on your screen.

What about the mouth? The oesophagus? Small intestine? And large intestine? Hopefully you were able to point at the screen in the right places.

Okay, So this is a little demonstration that's going to show us what it's like for our body to digest food.

So first let's imagine that this is the food and it's already been put in our mouths.

Okay I know that's difficult to imagine because it's all still kind of full.

So let's imagine that in the mouth I'm kind of using my teeth to break apart the food.

I'm breaking apart food with my teeth.

As I'm doing that, I'm using a little bit of saliva.

So I'm going to put some water to kind of help it all mix together.

So now it's kind of mixing and it is getting ready to be swallowed.

When it's swallowed, it's going to travel down through my oesophagus.

Now in particular, in particular, the canines and the incisors are going to help me kind of bite that food and tear it apart.

However, it's going to be the molars really that are going to help me kind of squash that food like that.

Okay, so the molars are helping me really squash that food.

Then it's going to go down through the oesophagus.

Now I don't have something to symbolise the oesophagus.

You're just going to have to kind of imagine it.

So I'm going to travel through the oesophagus onto the stomach.

I'm going to go straight to going into my stomach.

So I'm now in my stomach as you can see.

Now in the stomach, two things are going to happen.

One is that I'm going to be mixing with stomach acid or bile acid.

So I'm going to pour some orange juice, which is going to represent my stomach acid.

Just pour that in.

And then the second thing that's going to be happening is that my stomach muscles are going to be contracting and kind of squishing that together.

So I'm going to do that manually with my hands.

It's a strange texture, I'll be honest.

So, in my stomach, my stomach muscles are contracting.

Great.

Once it's going from my stomach, it's going to start to go into my small intestine.

Now I haven't got a small intestine with me, but I have got a pair of tights.

So I'm going to be using my tights to represent that small intestine.

First, I'm going to cut them just to make sure that I have kind of an opening there.

And I'm just going to pass along the liquid from my bag.

Not very beautiful this is, but it's working, going into my intestines.

Now in my intestines, the walls of my small intestine are going to be absorbing all the nutrients that are in my body.

So I'm going to be absorbing all the nutrients in my body, through my intestine.

It's going to be travelling all the way through my intestine, but you can see some of the orange juice coming out, that wouldn't happen, but you would see kind of in the walls, it would be absorbing the nutrients onto the bloodstream.

You'd be moving it along.

Eventually it would pass on to the large intestine, once I had absorbed all my nutrients.

So let's imagine I'm now in my large intestine.

Now in my large intestine, I'm eventually going to reach the anus and my waste is going to be removed from my body as faeces or AKA, another word for it, Poo.

There you have it.

That's the end of my digestive system.

Now that we've watched that incredible demonstration by myself.

You're now going to describe the steps of the digestive system for a final activity.

You're going to try to do this from memory, which is really going to help you remember it in the future.

You're going to use these key words on the slide to help you.

We've got the words, chewed, oesophagus, mouth, saliva, stomach, faeces, enzymes, small intestine, large intestine, absorbed nutrients, and anus.

And you can pause the video to complete the task.

You can resume, once you finished.

We have now finished our lesson and it is time for you to complete your exit quiz.

You need to exit the video and complete the quiz to test your knowledge and understanding of this lesson.

I hope you enjoyed the lesson.

Bye.