Bones
The bones in our body form our skeleton. They help to support our body and protect important organs. Bones also store nutrients and minerals, and they are places where blood cells are made. Humans have more than 200 bones in their bodies – all of different shapes and sizes. Like other parts of our body bones keep changing all the time. They are alive and grow, especially when you are young.
Parts of a bone
The outer surface of a bone is called the periosteum. It is a very thin membrane that has nerves and blood vessels in it. They carry nutrients to the bones.
The compact bone is the smooth and very hard part of the bone. It is the part you see when you look at a skeleton.
Spongy bone is lighter than compact bone but it is still very strong. It looks like a sponge or honeycomb with a lot of spaces in between.
The inside parts of a bone are hollow. They are filled with a jelly called bone marrow. In adults the long bones of the legs and arms are filled with yellow marrow. The ends have red marrow. It is the place where billions of new blood cells are produced every day.
When a child is born it has about 300 “soft” bones . As it grows up some of these bones grow together to form the 206 bones that a normal grown-up has. During childhood bones grow with the help of calcium. By the time you are about 20, bones stop growing.
The Spine and Chest
The spine is a special part of our skeleton. It has 26 small bones that look like rings and are linked together. These rings are called vertebrae. The spine lets you twist and bend your body and it holds your body upright. It also supports your head so that it can’t fall down. The spine protects the spinal cords which are the nerves that send information to the rest of your body.
Between each ring there are small soft discs. They keep the vertebrae from rubbing against each other and act as a pillow, so when you jump into the air and come to the ground again it doesn’t hurt.
Ribs are a cage of bones that protect the most important organs: your heart, lungs, liver and others. You can feel your ribs by touching your chest.
Most people have twelve pairs of ribs that look the same on the right and left side. They are attached to the spine in the back. In the centre of your chest there is a strong bone called the sternum. It keeps your ribs in place, so that they don’t fall apart.
Skull
The bones in your head make up your skull. They protect your brain. Some bones in your skull are fixed, so that you can’t move them. Others, like your jawbone can be moved. It opens and closes your mouth when you eat, talk or chew food.
Babies are born with spaces between the bones in their skull. As a baby grows the spaces disappear and the bones grow together.
Arms and hands
Your arms and hands make up a total of about 54 bones. They let you write, pick up things or throw a ball. Each arm is attached to a shoulder blade. There are two long bones in your arm which are connected through your elbow. These bones are wider at the ends and thinner in the middle.
The wrist connects the lower part of your arm with your hand. It is very flexible so you can twist it and turn it around in many directions. The hand is made up of small separate bones. Each finger has three bones, only your thumb has two.
Legs
A leg is made up of three bones. They are very large and strong and help support the weight of your body. They are connected to a group of bones called the pelvis, which supports the upper part of your body.
The longest bone of our body is the femur. It runs from the pelvis to the knee. The knee itself is protected by the kneecap. The ankle connects the lower part of your leg with your foot. The bones in your feet help you stand and balance your body.
Joints
A joint is a place that holds two bones together. Fixed joints don’t move at all. Some of them are in your skull and in other parts of your body.
Moving joints allow you to twist, bend and move different parts of your body. Some of them let you move in only one direction, others allow you to move freely in many directions. Joints have fluids in them, so they can work more easily and don’t hurt.
Diseases and injuries
Like all parts of the body our bones can also suffer from certain diseases. Bones need calcium to make them hard. If your body does not get enough vitamin D bones don’t have enough calcium, they become soft and curved. People suffer from osteoporosis when they have weak bones.
Bones can also break. In babies and young children broken bones grow together quickly, but when people get older it takes longer for bones to be repaired. In elderly people bones heal very slowly – sometimes not at all.
Joints also attract diseases when a person gets older. Arthritis is an inflammation of the joint that hurts and sometimes makes it impossible for you to move.
Taking care of bones
- Protect your skull bones by wearing a helmet when you ride your bike or do other sports.
- Wear elbow and knee pads when you go skating.
- Strengthen your bones by drinking milk and eating dairy products like cheese and yoghurt. They all have calcium in them, which makes bones harder.
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Related Topics
Words
- ankle = a joint that connects the foot to the leg
- attach = connect to
- attract =to be a magnet for
- balance =keep steady
- bend = turn
- billion = a thousand million
- blood cell =one of the cells in your body with blood; there are red and white blood cells
- blood vessel = a tube that carries blood from one part of your body to another
- brain = the organ inside your head that controls how you think and feel
- cage =a structure which protects something
- calcium = a chemical element that is soft and white. It is found in bones, teeth and chalk
- chest = the front part of your body between your neck and your stomach
- chew = to bite many times
- curved =bent, rounded
- dairy products = food that comes from the cow like milk, cheese, butter
- disappear = to go away so that you don’t see it
- disc = a round flat object
- disease = illness
- elderly = older
- especially = above all, mainly
- femur =the main bone in the upper part of your leg
- flexible = easy to bend and turn
- fluid =liquid, something watery
- grown-up = an adult
- heal = to become healthy again
- hollow = empty inside
- honeycomb = the place where bees put their honey. It has six sides and holes in between
- impossible = you cannot do it
- inflammation = part of the body becomes red and swollen when it is hurt
- it takes longer =you need more time
- jawbone = one of the bones that your teeth are in
- jelly =material that is very soft and moves easily when you touch it
- joint = a place that holds two bones together
- keep in place = in the correct position
- kneecap = small bone that covers the front of the knee
- liver = the part of your body that cleans your blood
- membrane = a very thin piece of skin that connects parts of your body
- nutrient =a food or chemical that gives people, animals or plants what they need to grow
- osteoporosis = when bones become weak and break easily
- pad = thick soft material that you can wear on your knees or elbows—it protects your joints
- pelvis =the curved bones which connect your body with your legs
- pillow =a soft material that protects something
- protect =defend, guard
- rub =to press something against something else
- separate =single
- shape = what something looks like = form
- shoulder blade = a flat bone at the top of your back
- skull = the bones of your head
- smooth = flat, even
- space =room, gap
- spinal cord = the nerves that are in your spine
- spine = the row of bones down the middle of your back
- sponge = something that is soft and full of holes
- store =keep, save
- strengthen = to make stronger
- suffer =to feel pain
- support = to hold something up
- surface =the top layer of an object
- thumb = short thick finger at the side of the hand
- twist = move, turn
- upright =standing straight
- weight =how heavy something is
- wide =broad
- wrist = joint between the hand and the arm