Related Links

The human body has several systems. A system is made up of several organs, or parts of the body, that work together. Some of the systems of our bodies are the skeletal and muscle system, the circulatory and respiratory system, and the digestive system.

The skeletal and muscle systems are made up of bones and muscles, of course. We will learn about bones first. Bones are hard and strong to hold up our bodies and to help us walk, for example. Bones are made up of cartilage in infants (cartilage is a tough and bendable material). Eventually, the bones harden from the calcium and minerals we eat to make the bones strong. Inside the bones there is bone marrow that is either red or yellow in color. The red marrow is where red blood cells are made, and the yellow marrow mostly stores fat. Bones are everywhere in our body, our heads, or skulls, are made of bone, and so are our fingers, toes, arms, and legs. In fact, there are more than 200 bones in your body!

The muscles are also found everywhere in your body. We have muscles in our faces, arms, hands, legs, stomachs, backs, and many more places. We have about 600 muscles in our bodies. Muscles are underneath our skin but on top of or connected to our skeleton (bones). Muscles are made up of fibers that helps us do such things as walk, lift, smile, and much more. If muscles are over-worked, they get tired and you may feel sore for a couple of days. But if you work your muscles for a short period of time, several times per week, your muscle will begin to increase in size. Many body builders work their muscles several times per week to get those "Popeye" muscles.

The circulatory system is the bood system in our bodies. Blood carries food and oxygen to different parts of our body. After "delivering" the food or oxygen, the blood returns and carries waste from the cells to the different organs in our body that will clean out the waste. The arteries are the thick tubes in our circulatory system that carries oxygen from the heart to the body. The veins carry the waste to certain organs and then back to the heart. The smallest blood vessels that can be seen on our hands, for example, are called capillaries. Blood is made up of plasma which has red and white cells in it plus platelets. Red cells give the blood its color and carry oxygen while white cells fight disease germs. The platelets helps the blood clot, or form a crust, when we get a cut or scrape; it will stop the bleeding.

The respiratory system is the system we use to breathe. We start breathing from our nose or mouth and the air travels down the trachea, or windpipe. The windpipe reaches the lungs dividing into two smaller tubes called bronchi. The bronchial tubes divide into smaller tubes and eventually into small air sacs. These air sacs have little balloons attached, called alveoli. They pass the oxygen into the capillaries that carry the oxygen into the arteries and around the body to the different cells.

The digestive system is the system that helps our body use the food we eat. We swallow the food after chewing it with our teeth. After the food is swallowed, it goes down a food tube called the esophagus, which takes the food down to the stomach. The stomach contains acid that makes the food break down into tiny parts. Next, the food goes into the intestines. First the food goes to the small intestine where the food is soaked up into the blood vessels. Food that the body can not digest, or use, is passed on to the large intestine where it eventually comes out of the body.

For our bodies to work well, it is important to eat healthy foods like fruits and vegetables and not much of junkfood. It is also important to get excercise to work our muscles and help us breathe well. Our bodies are important!

For Elementary Teachers

Florida Sunshine State Standard: Science: 3-5: Processes of Life

SC.F1.2.1