How does our breathing process work?

We take about 16 breaths a :minute and during times of stress the breathing process can speed up five or six times. While we sleep, it slows down to six or eight breaths a minute. Breathing seems like a simple process, but actually it is a highly complex operation.

With every breath about a pint of air reaches the lungs and seeps into the pores and pockets of spongy tissue. The thin walls of these air pockets are lined with fine capillaries carrying small red blood cells. The magic substance in these red cells is hemoglobin, a very complex compound made from iron and proteins.

Each molecule of hemoglobin contains four atoms of iron. When a red blood cell reaches the thin walls of the air sacs in the lungs, the iron atoms in the hemoglobin form loose partnerships with the oxygen in the air. This exchange takes place through the thin tissue lining the air sacs. The red cell, now carrying molecules of oxygen, is then swept along in the blood stream down into the left side of the heart.

With the next heart beats the oxygen .rich red cell is sent through the great aorta artery. Each pulsing beat sends it farther through the circulatory system into a network of finer and finer blood vessels. Along the way it brushes first one cell, then another needing fresh oxygen. The loose attachment between the iron and the oxygen is broken and the life giving oxygen is passed through the cell wall.

As the blood pulses along, the red cell also gathers waste carbon dioxide from the cells. Soon it starts the return trip to the heart, this time from the network of finer blood vessels to larger and larger veins. The red cell now carries carbon dioxide instead of oxygen.

It empties into the right side of the heart, and with the next pulse it is sent up again to the lungs.

The process is now repeated. The waste carbon dioxide is passed through the thin walls of the air sac. The red cell grabs four molecules of fresh oxygen from the pocket of air and returns to the heart to be sent out on another life giving trip around the body. The breathing process seems to be a simple business of letting air into and out of the lungs. Actually, this part of the operation is just a small part of the complex process of supplying vital oxygen to every living cell in the body.

It takes about eight minutes for a red cell to make the round trip from the lungs and back again. It is pushed along the route by about 560 heart beats, meantime the lungs breathe in and out about 126 times. Trillions of other red blood cells also are working so hard that each is worn out and must be replaced after just a few weeks.