Tuesday, July 17, 2012

The Muscular/Skeletal System (Explanation)


Hey guys. This post was originally meant to be just for the muscular system, but I really couldn’t see anyway I could explain the muscular system without talking a lot about the skeletal system. On the bright side, they will probably throw in a question or two about how the muscular and skeletal system work together in the PSLE.

( I am going to make it clear that I am only going to be talking about the parts of the skeletal system that helps us to move. I know the skeletal system also helps protect the important parts of the body from serious injury, but this post is mostly on how the muscular and skeletal system work together to help us move. )

So now that I have established what this post will be about, let’s start off. Everyone can move, us, dogs, cats, giraffes, the guy next door, EVERYONE! (All living things anyway) Of course, since I don’t want to clog this post with pointless info about how hippopotamuses can swim, I will only be talking about the human and skeletal system First off, I will go through the skeletal system, and then the muscular system and then I will talk about how they work together to help us to move.

Alright, starting off, I will be talking about how the skeletal system helps us to move...

How the Skeletal System helps us to move! Explained in 30 seconds!

First off, remember,  the skeletal system is made of BONES! Bones are found almost everywhere in the body. In the arm, legs, head etc.  Bones are usually really hard and impossible to bend. There are about 206 bones in the adult body. The skeletal system is also made of LIGAMENTS. (We shall go more into that later)

Your skeletal system is useful for 2 things:

  1. It gives your body its shape! It is the main structure/framework of your body. When your skeleton is sitting, you are sitting. When your skeleton is lying down, you are lying down. YOU AND YOUR SKELETAL SYSTEM ARE ONE!
  2. It also helps protect the body. 

Now that I have finished with that, let us use our legs for an example. Yes, the legs, not just your feet. As you should know, our legs have leg bones. (They also have leg muscles, but we will get more into that later) The leg bones are found inside the legs.  Let us look at a diagram of our leg bones.

leg bones

As you can see, there are  two bones in the leg.(Not including the bones in the foot) One is the upper leg bone, and the other is the lower leg bone. (Ignore the names in the diagram) These bones give your leg its shape.

Alright, it is simple enough so far. But there is actually a problem with having two bones. What is it? You ask, because it seems pretty okay in the diagram. Well, there is a problem, and I shall explain.

Well, at this point, I would like our audience to give a big round of applause to our celebrity guest, Mr Boxy! He is just like everyone else out there, except that his body is a box, and his leg bones are made of sticks.

And here he is:

Mr Boxy

As you can see, he now has 2 leg bones in each leg, the upper leg bone, and the lower leg bones. Both bones are separated. Almost immediately, you should see a problem. HIS LOWER LEG BONE ISN’T ATTACHED TO HIS UPPER LEG BONE! With no proper connection, his lower leg bone will just fall off and he will be left with just his upper leg bone. (Actually, Mr Boxy’s upper leg bone will fall off too, because there is nothing connecting his upper leg bone to his body.) Who will save this innocent box in this time of need? Who can he turn too? Well, it looks like it is a job for,..LIGAMENTS!!!

Ligaments are always found in between two bones. Ligaments are used to connect two bones together. Think of ligaments as rubber connectors.  Here, they connect the upper leg and the lower leg bones but at the same time, they are also flexible, so you can actually bend them. And when they bend, they are also bending your leg bones. And when they are bending your leg bones, they are also bending your leg. (Remember, your bones are the main structure of your body. So, your leg bones are the main structure of your leg) Here are some diagrams:

Mr Boxy with Joints

Now, everything is connected. Also, if you want, you can also bend the ligaments which will cause Mr Boxy’s legs to bend.  

Mr Boxy bending

[Also, you may be wondering why our body dosen’t just give us one leg bone for each leg and we wouldn’t need ligaments because nothing needs to be connected. Well, if you only had one leg bone per leg, then you can’t bend your leg! (Remember, it is impossible to bend bones)]

Mr Boxy with one leg bone

If you want to know where you can find ligaments, they are in your thighs, in your knees, in your shoulders, elbows, in your neck, in your back, in your fingers, in your toes and many other places as well. Can you find a similarity in these places? They can all BEND! Joints are there so that you can bend your body! That is the whole point of ligaments! They allow your body to bend! (They also connect the bones together.) That’s why they are like RUBBER connectors. If they were just normal connectors, our body wouldn’t be able to bend.

It is important that you are able to bend your body. This is because you can’t do ANYTHING without bending your body. You cannot move! Let’s take walking for example. When you are walking, the ligament in your thigh has bend your entire leg forwards so that you can move forwards. (If you don’t know where the ligament in your thigh is, it is shown inside Mr Boxy’s diagram above) If you didn’t have a ligament in your thigh, you wouldn’t be able to move your legs because your entire leg cannot bend. Another more obvious example is picking up a pencil. When picking up a pencil, you MUST bend your fingers in order to grab on to the pencil. Therefore, you MUST use the ligaments in your fingers.

Let’s recap: There are many bones in your body. They help give your body their shape. They also help to protect your body. Rubber connectors called ligaments are connecting these bones. These ligaments are flexible, and allow you to bend different parts of your body.

Now, before you start thinking that this post will only be about the skeletal system, I will be moving on to the Muscular System. You might be wondering what else the muscular system can do, since the Skeletal System already allows us to bend our various body parts. We will be talking about that later, but for now, I will be talking a little bit about muscles.

Muscles are everywhere in our body. In our face, arms, neck, legs and whatever other inappropriate body parts that you can name. Different people have differently shaped muscles, which is why there are people with huge, bulging muscles while there are people who look like they have nothing but skin and bones. Please note that when I say they look like they have nothing but skin and bones, it dosen’t actually meant that. Even they have muscles. That’s right: EVERYONE HAS MUSCLES.

Now, that I have finished with that, let us get into how the muscles work together with the bones to help us move. So bones can already do a lot of stuff. Bones, together with the ligaments, can let your body bend and twist and do all sorts of weird stuff. Well, think about it. When you are bending and twisting, what do you need? Before anyone makes a lame joke about what you need when you are exercising, the answer is energy. That’s right! When you are bending and twisting, you need energy. Now look at those thin bones! Do you think they have energy? (They don’t.)

That’s why you need muscles! The bones and joints give your body it's shape and they have can bend as well. However, they have no energy, so they cannot move around. That’s right! BONES CANNOT ACTUALLY MOVE ON THEIR OWN! But the muscles do have energy! In actual fact, the muscles are doing the work. They are the ones who are pulling the bones around. (I will explain more on that later.)  And that is how they work together  to help us move.

So, before I go on, let me explain something. Like I said, the skeleton is the main structure/framework of the body. So all the other body parts are just attached to the skeleton! (It’s true) This includes the muscles as well. The muscles are connected to the bones by things called tendons. (There’s no need to remember this, it is just an extra bit of info that I thought that I ‘d share)

All right, so here is a picture of the leg bones and leg muscles:

The System

This is obviously not the best drawing in the world, so you are forgiven if you can’t tell what is what. However, if you look closely at the drawing, there are two layers of muscles. (shaded in pink) One is in front of the bones, and one is behind. When these two layers of muscles are working together, they help the leg to move. How? Well, if you were paying attention before, the muscles move the bones by PULLING them. This is very important. The muscles PULL the bones. That is the only thing they can do. They can pull the bones. But this pulling of the bones, is what makes us able to move.

Here’s what happens when you lift your leg.

Bones and Muscles

As you can see, the upper muscle pulls upwards on the bone, and since the bone is the main structure of your leg, your leg is also pulled upwards.. (This line is incredibly important, because it tells us how our muscles move our leg)

And here is some more extra information for you guys! While pulling upwards, the upper muscle also stretches, causing it to become bigger. (If you check the previous diagram, the upper muscle is bigger) Of course, the ligament is bending, allowing your leg to bend.  You might also notice that the lower muscle becomes smaller when the upper muscle becomes bigger. Why is that?

Well, imagine there’s a large square cake in front of you for your birthday. You want to cover the top of the cake with icing. You have JUST enough icing to cover the cake. However, all of a sudden, a huge rectangular-shaped lump suddenly grows from your cake. You cannot remove it. The cake is now bigger, and you can’t cover it completely with icing anymore.

This principle also applies to our bodies. The skin is like the icing. We only have JUST enough skin to cover the whole body. The muscles are like the cake. When our muscles stretch, they become bigger, and we don’t have enough skin to cover them anymore. However, the body cleverly solves this problem by telling the other muscle to contract (become smaller). It is the body’s way of balancing out. One muscle becomes bigger, and the other becomes smaller. This way, there will always be enough skin to cover the body.

By the way, it also works the other way round. Your lower muscles can pull down to make your leg go down. This is what happens:

The double

When your lower muscles pull down, they pull your bone down, and because your bone is the main structure of your leg, it pulls your whole leg down too. And then of course, your body tells your upper muscle to contract (otherwise known as becoming smaller).

And actually, that is all! That is all that I need to say about how the muscular and skeletal system work together to make our body move. You might be a bit surprised, because inside here, you only saw your leg moving up and down. But remember, there are also a pair of muscles inside your thigh, your shoulders, your knees, your elbows, your fingers, your back, your toes, your neck and many other places. The muscles can also pull the bones inside there and cause these places to move as well. And, if they have the correct combination of pulling the muscles, they can do a wide variety of things. For example, with the help of the muscles and bones in your knee and thigh, you can kick a football. And the amazing thing is, the body ALWAYS (most of the time, anyway) knows which muscles need to be pulled in order to operate our body.

So, yeah, that is how the muscular and skeletal system work together. On a final note, I would like to apologize for taking so long to make this. I know that I said I would make this the next day after the comic was released, but I made a few major mistakes while making this and I had to rewrite this a few times. On another note, I will have to slow down the website a lot starting from now on. And I am being serious this time. I know that I said before that I was not going to be posting a lot and I would still post a lot, but this time I am serious. I might post a few times in the course of the PSLE revision, but overall nothing much will be happening here.

1 comment:

  1. Good post!

    Do not worry about the slow down. We will wait patiently for more great posts from you after your P.S.L.E. (Primary School *Last* Examination).