Human Travel Systems
We would like to take you on a marvelous trip through the skeletal system.In this trip you will view such sites as the working joints and bones and also the composition of the bone.We can't give away the whole trip quite yet so sit back and enjoy the ride.
First we enter the body by being miniaturized and we will enter as given a shot into the tibia.Now that we are inside the bone we will look at how the bone is built, and made up of.Bones are very strong.They are compared to concrete, or cast iron.Some bones can withstand pressure of 220kg pscm.About 45% of the material of a bone are nonliving.The minerals are usually calcium and phosphorus; they give the bone strength.Living cells & blood make up 30% and 25% water.Bones have three layers.Thefirst is a thin covering of cells that form a tough protective membrane are the bone. A membrane called the periosteum surrounds individual bones.The second layer is a hard, white, rocklike mineral.The last layer of the bone is the marrow.It is lighter than the other materials. Although all bones don't have the same three layer setup.Short bones and many flat bones are mostly sponge, surrounded by a thin layer of hard bone.As children grow up they go through a transformation with their bones called ossification.When this processes happens the cartilage turns to bone.
Next we hike up the steep yet very hard bone.As we go up the bone to get to the femur we must go over a hinge joint.A hinge joint is one of four of the major joints.The hinge joint allows only a back and forth movement, it is like a door hinge.Some examples of hinge joints are elbows and knees.Another type of joint is the ball & socket joint.This joint allows movement in nearly all directions.It gets its name because the ball like end of one bone fits into the socket like end of another bone.Some examples of the ball and socket joint are your hip…