Eric Goldenstein, age 10, of bountiful., utah, for his question:
How do our lungs work?
Our lungs work day and night, whether we are sleeping or awake. They never cease working throughout our entire lives, and most of the time we do not even notice that they are busy. Their work is done automatically, without any help from our conscious minds. The living cells of the body need a constant supply of oxygen. They also must get rid of the waste carbon dioxide gas which is created as the oxygen is used. The lungs play an important role in this vital operation. They place a supply of oxygen where it can be reached by the blood. The blood stream totes the oxygen around the body where it can reach the living cells. The lungs also get rid of the body's waste Carbon dioxide.
The two lungs are made of spongy tissue, riddled with small holes cal.led air sacs. There are about 700 million air sacs in an average pair of healthy lungs. The air sacs are lined with thin thin skin. If all this thin membrane were spread out in one flat piece, it would cover an area of about 100 square yards. When we breathe in, we inhale about a pint of oxygen rich air, which fills the Air sacs of the lungs. The tissue between the air sacs is filled with tiny blood Vessels. They are so small that red blood cells have to pass through them in single Me and these red cells are so tiny that 300 million of them crowd into a single drop of blood. In the lungs, the red cells are separated from the air by the thinnest of thin membranes.
Every red cell is stuffed with an amazing protein cal1ed hemoglobin. A molecule of hemoglobin contains the chemicals heme and globin, plus four atoms of iron. When a red cell reaches an air sac, the iron atoms of hexaoglobin take mo1ecules of oxygen right through the membranes. The four iron atoms in a mo1ecule of hemoglobin form loose attachments with molecules of oxygen, and the blood stream sends the oxygen rich blood on its way pulsing through the body. The cells needing oxygen take it from the Hemoglobin as the red ce11s pass by the blood delivers oxygen and gathers up waste carbon dioxide from the busy cells. It returns to the lungs, and the waste gas seeps into the air sacs. When we breathe out, the waste carbon dioxide is squeezed out of the body.
Carbon dioxide is gathered from the cells by hemoglobin and by other proteins in the blood. It is carried back to the lungs in the form of bicarbonate. When it reaches the lungs, this chemical is changed back into carbon dioxide gas. In this form, it enters the air sacs and the lungs heave it out into the air.