Lesson video

Hi there, I'm Mrs. Kemp and welcome to today's lesson all about muscles.

I'm absolutely delighted that you are here to learn with me today.

So let's get started.

Okay, so our lesson today, as I said, is all about muscles and it fits into the Human Skeleton and Muscles unit.

Some of the information you will recognise from when you've learnt about cells during key stage three and also some of the information from when you were at primary school about the skeleton and also the digestive system actually.

So what you'll be looking at today is I can describe what muscles are made of and how they move.

During the lesson, we will be using all of these keywords.

I'm not going to go through them now, but if you do want to stop and read these, please do pause the video.

I will go over each one of these and explain them in detail as we go through the lesson.

We've got three learning cycles today.

We've got muscle tissue, the different types of muscle, and how muscles work.

We're going to start with the first learning cycle today, which is muscle tissue, okay then.

So we actually find muscles all over our body.

It's probably a word that you already recognise and you might already have a good idea about where we find some of those muscles.

We've got an image here that's showing the muscular system and all the different places where we find those muscles on our body.

Now actually muscles are a living tissue and therefore they're made up of specialised cells.

The type of cell that makes up muscle tissue is called a muscle cell.

We can see a picture of it here on the screen.

We might remember this cell from when we've learnt about specialised cells in the cells topic previous.

So when you learn about cells, you learn about a typical animal cell, and this is a typical animal cell here on the screen.

A typical animal cell has all the parts like mitochondria, cell membrane, nucleus, and cytoplasm.

You might remember what some of these different parts do.

Have a little think, see if you can think about them.

So the mitochondria carry out aerobic respiration.

The cell membrane allows things to move in and out of the cell.

The nucleus contains genetic information and the cytoplasm is where all the chemical reactions take place in the cell.

A muscle cell then is a type of animal cell, but it is what we call a specialised cell 'cause it's got certain features that allow it to carry out its function easily.

Let's have a little look at what they look like.

Here's one that's just appeared on the bottom of the screen so we can see that comparatively to that animal cell.

Actually, it's really long and thin.

It's important that it's long and thin because it needs to be able to contract and then relax.

So in order for it to carry out its function, it gets shorter and then gets longer again.

See, this is why it's got that much thinner longer shape compared to the typical animal cell that is above.

Okay, let's go to our first check then.

This check is a true or false.

Muscle cells have only a nucleus and mitochondria.

Do you think that is true or false? Can you justify your answer? A muscle cells are animal cells, so it also contain cytoplasm and are surrounded by a cell membrane or B, muscle cells require lots of energy, so need to make their own food.

I will give you a short time to think about this.

However, if you need more time, please feel free to pause the video.

Okay, did you get false for your first answer? And the reason that it's false is because muscle cells are animal cells, so they also contain cytoplasm and are surrounded by that cell membrane.

So it's not just the nucleus and mitochondria.

Okay, so muscle cells are very, very small.

We would not be able to see a muscle cell just with our own eyes.

So in order to be able to see a muscle cell, so the reason that we know that they're long and thin in that way is because we are able to use a microscope.

You may have had a go at using a microscope at some point, especially during the cells topic that you may have already covered.

You can see that what the microscope uses are lenses and those lenses are found inside the microscope and what they do is they magnify the image.

What that means is, is it makes the picture larger so that we're able to see more detail inside and it allows us to see those individual cells.

So we would use a microscope to see most cells, to be honest, as most cells are too small to be able to see with the naked eye.

Let's go to on the second check of this learning cycle.

So for this one you need to complete the sentences.

So we have muscle is a living blank.

It is made up of specialised blank, which can be seen using a blank.

Can you fill in those blanks? I'll give you a few moments to think about it, but if you do need more time, please do pause the video.

Okay.

Did you get the muscle is a living tissue.

It is made up of muscle cells, which can be seen using a microscope.

Okay, fab, well done.

So we're going to move on to our first task today.

This is task A.

It can be found on your worksheet.

So if you want to be able to record what you've thought about, please do get your worksheet out now.

So first of all, could you draw and label a muscle cell, making sure to all the parts of the cell that we've discussed already, how do we know a muscle is a tissue? And finally number three, explain how muscle cells are specialised for their function.

Again, I'll give you a short amount of time to think about it.

If you needed a bit more time, then please do pause the video.

Okay, let's have a look at what those cells look like then.

So here we've got our muscle cell.

Remember it's got that really nice thin, elongated shape and we have labelled the cell membrane all the way around the outside we've labelled those mitochondria, that large circle, which we call the nucleus.

And then all the jelly-like substance that makes up the rest of the cell that's known as the cytoplasm.

So we know that a muscle is a tissue because it's made up of those muscle cells.

We can only see muscle cells using a microscope.

Muscle cells are specialised for their function as they have a really long shape in order to allow them to contract and relax.

Okay, I'm sure you've done really well on those.

So that's excellent.

We'll move on to our second learning cycle.

So our second learning cycle of today is called the different types of muscle.

And you may already be familiar with some of the types of muscle, okay? But there are actually three different types and you may never have categorised them before.

So this might be completely new learning.

So the first type of muscle is the muscle that you will probably recognise and it will be much more familiar to you.

When we talked earlier about the sort of muscles that you might know about, you know like in your arm, this is what we're talking about.

We're talking about skeletal muscle and skeletal muscle is joined to our bones.

However, there is also another type of muscle, and this is called smooth muscle.

You may never have named it before, but you will have talked about it in that digestion topic, sorry, that you did back in primary school.

We can see here that this is the digestive system, so we can already assume that actually smooth muscle makes it part of the digestive system.

The last one is the muscle that's found in the heart.

The heart finds cardiac muscle and it's a type of muscle that is only found there.

Okay, let's do a quick check then.

So which of the following are not a type of muscle? Is it A, skeletal muscle? Is it B rough muscle, or is it C, cardiac muscle? Okay, I'll give you a little bit of time to think about it, but if you do need more time, you can just pause the video.

Okay, did you get B, rough muscle? Of course, rough muscle is not a type of muscle.

Only skeletal or cardiac are types of muscle.

Let's go onto our next part then where we're going to look at each of those different types of muscles in a little bit more detail.

We're going to start with the more familiar type of muscle, okay? Which is that skeletal muscle.

Skeletal muscle, remember, is attached to bones, all right? And what its job is, is to move those bones.

Okay, so the reason that I can move my arm backwards and forwards is because I have muscle that is found there and then attached to my bone.

How I'm able to do that then is that I can actually think about that and conscious thought allows me to control the contraction of those muscles.

Okay, so my brain is sending instructions to my muscles in order to be able to move them.

My muscle is actually only able to pull on that bone and it moves the bone around what we know as a joint.

In my example here of my arm, it is my elbow.

That is the joint, if you remember from when you've learned about the skeleton.

Then a joint is where two bones meet together, okay? So in this example it's my elbow and my muscles in my arm are able to move that bone around my elbow.

The second type of muscle then is the muscle that is found in the heart.

The heart remember is part of your circulatory system.

Your circulatory system is moving blood all around your body all the time, through all of those tiny little blood vessels that you find throughout your body.

The heart then has got this special type of muscle called the cardiac muscle.

Unlike skeletal muscle then, we cannot contract our cardiac muscle using our conscious thought.

It actually happens automatically.

I have never had to think about making my heart muscle beat.

It does that without me thinking.

So it's doing it all the time, contracting and relaxing, contracting and relaxing.

And what that does is it pumps that blood all the way around my body to all of the cells in my body.

It's really important because that blood contains many things that are very important to keep my cells all over my body alive.

And we will have a little bit of more of an in-depth thought about that later on in the slides.

So the final type of muscle is called smooth muscle.

This one again, just like cardiac muscle is actually involuntary.

I cannot think about moving my smooth muscle.

It's happening all the time without my conscious thought.

It's automatic, it's found in many of the organs over the body, but the ones that are probably more familiar to you are those ones that are found in our digestive system such as the oesophagus, the stomach and the intestine.

So we can see on that little image there that's appeared, the ones that or the places, sorry, where those different organs are found.

The role of that smooth muscle then is to contract to push food along that digestive tract.

So when I eat food and I chew it up and I swallow it, what happens is that those muscles, that smooth muscle in my digestive system constantly contracts again without any of my conscious thought, I do not need to think about it to push that food through.

Okay, without it doing that, it wouldn't actually travel down my body and I would never get the nutrients that I needed from it.

Let's go to a quick check then.

So which diagram shows where cardiac muscle is found? Is it A, B, or C? I will give you a moment to think about it, but if you need more time, please pause the video.

Okay, did you say C? Excellent, well done.

Cardiac muscle of course is found in the heart and the heart only.

All right, so it's that special type of muscle that allows the heart to be beating without any conscious thought.

Which type of muscle is involuntary? Is it A, cardiac muscle? Is it B, skeletal muscle or is it C, smooth muscle? Again, I will give you a little bit of time to think about it, but if you do need more time, please pause the video.

Fantastic, it is the cardiac muscle which we saw on the previous check and also smooth muscle, which remember, is found in lots of different organs in your body and in particular those ones that we find in the digestive system.

All right, we're moving on to our second task of today.

I'm going to show you what Andeep has said and then I'm going to read out what Aisha has said.

So Andeep, he says, I think you can build and strengthen all of your muscles in your body at the gym.

Aisha says, I disagree because of smooth muscle.

Can you build on Aisha's comment to explain to Andeep why you cannot strengthen all muscles at the gym? So you can find somewhere to write your answer on the worksheet, however, you may just be thinking about it, but if you do need more time than the time that I'm going to give you to think about it, please do pause the video.

So did you come up with all of these ideas? Skeletal muscle can be moved voluntarily.

You can actively move and strengthen skeletal muscle when exercising.

Cardiac muscle is an involuntary muscle.

As a result of exercising, your heart muscle will grow bigger and stronger because you need to pump more blood to the muscles.

Smooth muscle is an involuntary muscle found in organ systems. It will not be affected by exercise.

I hope you got a lot of those.

If not, you might wanna add a couple more into your answer.

Excellent, well done.

Onto our final learning cycle then, how muscles work.

So here's our muscle cell again, okay? Remember it's got that long, thin shape and remember that what it needs to do is it needs to be able to contract.

Now in order to be able to contract, it needs to be provided with energy.

The fuel that the cell uses for that energy comes from oxygen, oxygen and glucose.

Okay, glucose is a name of a type of sugar that we use in our cells.

Where do we get these things from them, when we breathe in, okay? We breathe in air and the oxygen that is in that air is able to transfer from inside our lungs into our blood, the glucose we get from our foods.

So when we eat foods like starchy foods like potatoes and bread, or when we eat sugary foods like cakes, what happens to those is that they go through our digestive system and get broken down and then they get absorbed into our blood.

Okay, so we've got oxygen and glucose in our blood.

They travel around in our blood, okay, in order to get to those cells, what happens to them when they get to the cells then? Remember, when we saw that muscle cell earlier, you may have noticed that actually it seemingly has more mitochondria than a typical animal cell does.

This is important, okay? And that's because it's the mitochondria where that chemical reaction happens called cellular respiration.

This is how oxygen and glucose are able to provide that energy, through that process called cellular respiration.

Now all of our cells will respire and in fact, all living things need to respire.

However, because the muscle cells require more energy because they need to contract, all right, they need more energy than your usual typical cell.

So the oxygen and glucose is supplied to the muscle cells by the blood.

So remember we take in oxygen from the air and it passes from our lungs into our blood and we take in glucose in our food and it passes from our digestive system into our blood.

They then travel around in the body as part of our circulatory system, to every single one of our cells.

They are then transferred into those cells, they make their way to the mitochondria where cellular respiration happens to provide that energy.

The muscle cell will use that energy in order to be able to contract.

And you can see that when that cell contracts, what happens is the cell changes shape and becomes shorter.

It will then relax back to its original shape.

You can see that in that second cell there, it's become elongated again, so long and thin, but actually that part of the process does not require energy.

Only the contraction requires energy.

Okay, let's go to another check then.

True or false, a muscle cell only uses energy when it contracts.

Can you justify your answer? A, a muscle cell needs energy to contract and relax.

B, a muscle cell doesn't need energy to relax.

If you needed more time, please do pause the video.

Otherwise, hopefully you got true, okay? And that is because a muscle cell does not need energy to relax.

It only needs energy in order to be able to contract.

Okay, our final task of the day, task C, and this is a describe question, describe then what a muscle cell needs for contraction, where it gets these things from and where they are used in the cell.

Now, remember that you can jot down your ideas on the worksheet and if you need more time, please do pause the video.

All right, then let's have a look at some of the ideas that hopefully you've got down.

Muscle cells need oxygen and sugar for respiration, we breathe in oxygen, we get sugar from our food.

Oxygen and sugar are transported to the muscle cell via the blood.

Oxygen and sugar are used in the mitochondria as fuel for cellular respiration.

The muscle cell has many mitochondria to provide energy so that it can contract.

Have a little look at those, see whether or not you've got all the points.

If not, feel free to add a couple more in.

So we've come to the end of the lesson today.

I hope that you've enjoyed this learning journey with me and let's have a little summary then of what we have learned today.

So muscle cells are found all over the body.

They are a living tissue made up of specialised cells and they can contract and relax.

There are three different types of muscles, skeletal, cardiac and smooth.

Skeletal muscles are attached to bone and can be found in the skeletal system.

Cardiac muscle is found in the heart and can be found in the circulatory system.

Smooth muscle is found in most of the organs in the body, including the digestive system.

Muscle cells use oxygen and sugar and cellular respiration to provide energy for muscle contraction.

Thank you very much for learning with me today and I look forward to seeing you again, bye.