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The Human Skeleton
Here are some words that you might find useful:-
Ribs – these are the bones that protect your major organs (heart, lungs etc). Humans have 12 on ribs each side of their body.
Spine – this is sometimes called the backbone. It’s actually made up of lots of ring shaped bones.
Skull – this is the bone that protects your brain.
Contract/Contraction – to get shorter, muscles contact to move your bones.
Relax – when a muscle relaxes it gets longer.
Vertebrate – sometimes called the spine.
Words To Describe Your Bones
Here are a few words that describe your bones:-
Hard, weak, strong, rough, smooth, solid, brittle, hollow, same shape, different shape.
Your bones make up your ‘skeleton’ – this is a good word to remember.
Below are pictures of a human skeleton and the skeleton of a horse. Can you see the similarities? Can you see any difference?
Differences In Skeletons
Try to find the answer to these two questions:-
Who has the longest arms, boys or girls?- Are adult’s heads bigger than children’s heads?
- What Does Your Skeleton Do?
The main functions of the skeleton are:-
To provide support.
To provide protection and enable movement.
It is also worth knowing that in some bones of the human skeleton red blood cells are produced. The skeleton also provides a mechanism for storing calcium.
Types Of Skeleton
The Hydrostatic Skeleton:
Examples of the hydrostatic skeleton can be seen in molluscs and worms. These soft bodied animals rely on pressurised fluid held in compartments within the body to act as a skeleton. By using muscles surrounding these compartments, the animal is able to change its shape and produce movement.
In earthworms, the hydrostatic skeleton consists of fluid held in a compartment called the coelon. The coelon is divided into segments and by using muscles surrounding these segments to push the fluid the earthworm is able to change shape. By squeezing some segments but allowing others to relax, the worm moves using a peristaltic motion.
The Exoskeleton:
Exoskeletons, as the name implies, are skeletons which encase the organisms body. Examples include insects and spiders.
The exoskeleton (also called the cuticle) is primarily composed of chitin, a substance similar to cellulose. Chitin, whilst light, is quite strong and offers the animal some protection, it also serves to reduce water loss.
Where greater protection is needed, the chitin is reinforced by the addition of other organic compounds which produce cross-linking of the proteins. This cross-linking makes the skeleton less flexible but increases its strength. If further strengthening is required, for example in the claw of a lobster, calcium is added.
You may have wondered why animals with an exoskeleton tend to be small (there are no eight foot spiders about thankfully). The reason these animals tend to be small lies in the structure of the exoskeleton itself.
To enable movement, the exoskeleton is largely composed of thin hollow tubes, this allows the animal to be flexible and hence be able to move, whilst at the same time offering some degree of protection.
If the animal were much larger the exoskeleton would need to be much thicker and consequently much heavier. Such a heavy skeleton would severely limit movement to a point where movement became impossible. You might have noticed that the larger exoskeleton bearing animals tend to move slowly.
Endoskeletons:
As with exoskeletons, the very name "endo" tells us that these skeletons are found within the body of the animal.
Whilst there are examples of invertebrate endoskeletons (the star fish being one) we shall concentrate on the vertebrate skeleton and, in particular, the human skeleton. It is worth noting however, that when we think of "the skeleton" we tend to think of bone, whilst this is generally true of the human skeleton it is not the case in some species of fish. Sharks and rays, for example, have skeletons composed of cartilage. This much softer, lighter material affords them great speed, a distinct advantage for a predator. (It was thought that such cartilage skeletons indicated an early evolutionary stage but recent evidence suggests that these may actually have evolved from bony skeletons). The human skeleton also contains some cartilage - for example the ear.
The Human Skeleton:
The human skeleton not only provides support, protection and a means of locomotion and movement, but (in some bones) is involved in the production of red blood cells. The skeleton also provides a mechanism for storing calcium.
Click the link buttons below for more information about skeletons and moving and growing:
Exercise And The Human Body
What can we do to get some exercise?
Adults and children exercise in many different ways. The effect of exercise on health depends on what exercise is been carried out, how long the exercise has lasted and the frequency of the exercise. Some different forms of exercise and the likely effects are shown below.
Remember that any activity that makes you use energy is exercise - even tidying your room!!
Walking - this is a gentle form of exercise. It is a good way to start if you haven't had much exercise for a while. Walking exercises the leg muscles, the heart and lungs.
Swimming - is a very good, all round exercise activity. Swimming regularly exercises all the major muscles in the body.
Running - this is a very demanding form of exercise. You will exercise your heart and lungs. Running should be increased steadily to avoid getting out of breath quickly.
What Jobs Do Muscles Do?
The muscles in your body are very important - they enable you to stand up, sit down and move around.
Without muscles you would be unable to move. Some muscles work without you needing to think about it.
Many muscles work to help you to
breathe. Some movements need muscles to
work together.
The Human Skeleton:
What happens to breathing and the heart during exercise?
Heart
During exercise the heart needs to beat faster so that oxygen can be transported around the body. The oxygen supplies the muscles that are working hard. If the muscles are used for too long they become tired and start to ache.
What happens after exercise?
Heart
After exercise muscles will feel tired. After resting, they will recover. It is important to make sure that exercise activity slows down gradually rather than just stopping. This helps the body recover more quickly.
Breathing
After exercising the rate of breathing slows down. The muscles no longer need as much oxygen because they are not working as hard.
- Find out what happens when you exercise.
Equipment needed:-
- A timer or watch with a minute hand
- Suitable shoes for running on the spot
Task:
Measure your pulse rate by gently placing pressure on the inside of your wrist with two fingers- Time your pulse for 60 seconds - record this number. This is your resting heart rate
- Run on the spot for 1 minute
- Take your pulse again. Record how your body/muscles feel
- Run on the spot for two minutes and repeat the exercise - record the results and note any changes
- Time your pulse again every two minutes to see how long it takes to return to the 'resting' rate
Things to look out for:
- When you exercise your heart rate pulse should increase
- When you exercise you should begin to feel hotter
- When you exercise you may begin to feel tired
Remember, as a member of the Science Bus Club you can ‘Ask Albert’ a question about any of the topics. So if you’re not already a member join today!!
