Essay about Skeleton system (science)

Skeleton System

What I will be talking about will be about the skeleton. There are many bones in the skeleton .I will be talking about the bones and how they function in the skeleton.
Humans and most of the animals have a skeleton to support their body. The bones protect the soft parts of your body such as your heart and lungs. Our bones are joined together by different joints that let us move. The muscles fixed to the bones in different directions to make us move. An adult has about 206 bones, all joined up to make up a skeleton. Bones are made of millions of tiny cells.
The hard outer layer of a bone protects the spongy bone inside. The marrow, where red blood cells are made, is in the center of the bone. There are two types of marrow, red marrow and yellow marrow. The yellow marrow has fatty connective tissue and fills the marrow cavity. During starvation, the body uses the fat in yellow marrow for energy. The red marrow of some bones important site for blood cell production. Here all erythrocytes (red blood cells), platelets, and most leukocytes (white blood cells) form in adults. From the red marrow, erythrocytes, platelets, and leukocytes migrate to the blood to do their special tasks. Red blood cells carry oxygen and nutrients to the body tissues. Platelets help in blood clotting. White blood cells help fight disease and infection. The ends of the bone are protected by tough, rubbery cartilages.
The first bone that is in the skeleton is the skull. The skull protects the brain, and the ribs protect the heart and lunges in your chest. The second bone is called the jawbone. The third bone spine then comes the collarbone. The fifth bone is the sternum. The sixth bone is called the ribs. The seventh bones are called the forearm bones. The eighth bone in the skeleton is called the pelvis. Then comes the fingers. The tenth bone is called the femur. The eleventh bone is called the kneecap. The twelfth bone is called the shin bone. The thirteenth bone in the skeleton is called the calf bone. The fourteenth bone is called the ankle bone. The last bones in the skeleton are the toes, but in the adult skeleton there are 206 bones. The longest bone in the skeleton is the femur or thigh bone, is about 20 inches long in a person who is 6 feet tall. The smallest bone is the stirrup inside the ear. How do we move? We move because the brain controls everything we do, how we think, feel, or do. Messages from different muscles reach different parts of the brain. When we think about doing something our brains decide what movements to make. The muscles, when you want to run or skip, those muscles are called the voluntary muscle because they work when we tell them to. Voluntary muscle is something that does not happen automatically, but which is controlled by thought. We use voluntary muscles when we chew and swallow our food. After that, involuntary muscles take over to help us digest the food. Involuntary muscle is something that happens automatically, without thought.
We have different joints in our body that are joined together. There are the Ball- and -Socket joints like we have in the hips and shoulders. Those joints can move in almost any direction. Another joint, is the Hinge joints, like those in the elbows, knees, fingers, and toes, they can only move backwards and forwards. The Gliding joint is the next joint. Those in our wrists and ankles can bend and turn. The movements of the joints are controlled by ligaments. Ligaments tie the joints together and hold the bones firmly in place. In some joints there is a layer of liquid between the bones to stop them from rubbing together. Between the joints of the spine are soft pads of cartilage which separate the bones and cushion the spine from any shocks. The flat bones of the skull are joined together by the fibrous joints which do not allow any movements.
We make all our movements by using muscles. The muscles up of bundles of thin

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Essay on Skeletal System