What would happen if humans didn't have bones? You'd be floppy like a beanbag. Could you stand up? Forget it. Could you walk? No way. Without bones you'd be just a puddle of skin and guts on the floor.
Bones have two purposes. Some, like your backbone, provide the structure which enables you to stand erect instead of lying like a puddle on the floor. Other bones protect the delicate, and sometimes soft, insides of your body. Your skull, a series of fused bones, acts like a hard protective helmet for your brain. The bones, or vertebrae, of your spinal column surround your spinal cord, a complex bundle of nerves. Imagine what could happen to your heart and lungs without the protective armor of your rib cage!
How many bones do humans have? When you were born you had over 300 bones. As you grew, some of these bones began to fuse together. The result? An adult has only 206 bones!
How do my bones move? With a lot of help. You need muscles to pull on bones so that you can move. Along with muscles and joints, bones are responsible for you being able to move. Your muscles are attached to bones. When muscles contract, the bones to which they are attached act as levers and cause various body parts to move.
You also need joints which provide flexible connections between these bones. Your body has different kinds of joints. Some, such as those in your knees, work like door hinges, enabling you to move back and forth. Those in your neck enable bones to pivot so you can turn your head. Still other joints like the shoulder enable you to move your arms 360 degrees like a shower head.
Are your bones alive? Absolutely. Bones are made of a mix of hard stuff that gives them strength and tons of living cells which help them grow and repair themselves. Like other cells in your body, the bone cells rely on blood to keep them alive. Blood brings them food and oxygen and takes away waste.
If bones weren't made of living cells, things like broken toes or arms would never mend. But don't worry, they do. That's because your bone cells are busy growing and multiplying to repair the break! How? When you break your toe, blood clots form to close up the space between the broken segments. Then your body mobilizes bone cells to deposit more of the hard stuff to bridge the break.
What's bone marrow? Many bones are hollow. Their hollowness makes bones strong and light. It's in the center of many bones that bone marrow makes new red and white blood cells. Red blood cells ensure that oxygen is distributed to all parts of your body and white blood cells ensure you are able to fight germs and disease. Who would have thought that bones make blood!?!
Do all critters have a backbone? Nope. In fact, some 97% of critters on earth don't have a backbone or spine. Remarkably enough, of those that do have a backbone, there are lots of similarities: a skull surrounding a brain, a rib cage surrounding a heart, and a jawbone or mouth opening.
The human hand has 27 bones; your face has 14!
The longest bone in your body? Your thigh bone, the femur -- it's about 1/4 of your height. The smallest is the stirrup bone in the ear which can measure 1/10 of an inch.
You have over 230 moveable and semi-moveable joints in your body.
The spine is the central support for the body. Another word for the spine is the backbone. The spine is made of separate irregular bones called vertebrae. The vertebrae are made up of spongy or cancellate bone surrounded by a layer of compact bone. In between each vertebrae is a layer of cartilage that keeps the bones from rubbing against each other.
There are twenty six vertebrae in the spine. Although each vertebrae can only move a little bit, the total spine is very flexible. The spine of a human being is curved. Most other mammals have a straight spine. The curves allow the spine to support and balance the body on only two legs.
Many people develop back problems as they get older. The discs start to wear away. The vertebras come out of place causing pain. The back gets stiff and makes it difficult to move.
The breastbone, or the sternum, is linked to the bones which make up the ribs. The sternum is a flat bone that is about 6 inches long. The ribs curve around from the spine to the front of the body. This makes a bony framework which is known as the thoracic case. This case helps protect your chest.
Most people have 12 pairs of ribs. The ribs are connected to the sternum by cartilage. This makes the ribs more flexible, which is necessary during breathing. The first seven pairs of ribs are attached directly to the breastbone. The eighth, ninth and tenth pairs are attached to the sternum by a cartrilage band. The last two pairs of ribs are not attached to the sternum or cartilage. The last five pairs of ribs are called false ribs.
The bones of the hands and feet are flexible. The foot has twenty-six bones, one less than in the hand. The bones in the toes are shorter and fatter than the bones in the fingers. This helps us to balance on two feet.
The seven bones in the ankle are called tarsal bones. The main part of the foot is made of metatarsal bones. Phalanges are the bones in the toes. The arch in the foot helps to support the body's weight. Each hand has twenty-seven separate bones. These are connected with muscles and tendons. Hand bones are also called the metacarpus. Just like the foot, the bones in the fingers are called phalanges.
The fingers have three phalanges and the thumb has two. These joints allow the finger to flex. Because of this, the human hand can make more precise and finer movements than other creatures.
The Skeletal System Interesting Facts
The largest bone is the pelvis, or hip bone. In fact it is made of six bones joined firmly together.
The longest bone is the 'femur', in the thigh. t makes up almost one quarter of the body's total height.
The smallest bone is the 'stirrup', deep in the ear. It is hardly larger than a grain of rice.
The ears and nose do not have bones inside them. Their inner supports are cartilage or 'gristle', which is lighter and more flexible than bone. This is why the nose and ears can be bent.
After death, cartilage rots faster than bone. This is why the skulls of skeletons have no nose or ears.
. What are the five major jobs of the skeletal system?
2. What do you call the part of the skeleton which protects the brain? How many bones are in a baby's head?
3. The parts of the skeleton which protect the heart and lungs are called the _______.
4. What do you call bendable places where some bones join together? Name six types.