Exhaling for Life

Carbon dioxide is the natural byproduct of cellular metabolism. As most people know, we inhale oxygen from the air around us and exhale carbon dioxide (CO2). Everyone knows why we need to inhale oxygen, but not many know why it is important to life that we exhale CO2. That’s the focus of today’s post.

CO2, when combined with the water in our blood, becomes carbonic acid. As carbonic acid builds up in our blood system, the acidity of our blood increases. But there is a limit as to how much acidity our body can tolerate. A significant increase for too long – an hour or less in many cases – will kill us. One the other hand, too little acidity in our blood for too long will also kill us.
Now here is where we are either the product of an extraordinary chain of lucky evolutionary events – or we are the product of an extraordinary intelligent Creator.
Near the part of our brainstem called the ‘medulla’ are specialized cells called chemoreceptors. Those cells respond to changes in the acidity of our blood. When those receptors sense an increase in acidity, the receptors send impulses to the medulla to increase the rate and the depth of our respirations. The medulla, in turn, signals our diaphragm and the muscles in the rib cage to breathe faster and deeper.

That, in turn, ‘blows off’ excess CO2, leaving less of it hanging around to become additional carbonic acid.

The opposite occurs when the chemoreceptors sense too much of a decrease in the blood’s acidity. The respiratory center in the medulla signals our diaphragm and muscles of the rib cage to slow the rate and depth of our breathing. That results in our blood retaining more CO2, making it available to become carbonic acid.

This exquisitely delicate and precise balancing act occurs with every breath, moment by moment, hour by hour throughout our lives. It occurs with meticulous detail whether we are asleep or playing soccer, studying for exams or watching a movie.

Here’s the point.

Either that precise and life-sustaining balancing act happened all at once and by complete accident – or the Creator set it up to work as it does.

Moment by moment.


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