If you didn’t know, the carotid body is a small organ located at the upper end of the carotid artery. It contains nerve fibers and other cell types that, among other things, sense blood gas concentrations. This, in-turn, plays a role in controlling the breathing rate. Di Giulio describes a part of the carotid body that becomes infiltrated with lymphocytes and fibrosis during aging. One type of cell in this organ has a shrunken nucleus and an accumulation of lipofuscin. Moreover, a reduction in mitochondrial number and volume has been observed. These age-related changes appear to converge to make the organ less responsive to hypoxia—the relative deficiency of oxygen in the blood. Hypoxia can cause fatigue, lethargy, tissue dysfunction, headache, confusion, reduced exercise tolerance, and poor sleep quality, among other side-effects.

If you suspect you might be suffering from not enough oxygen in your blood—a related condition called hypoxemia—it’s relatively easy and inexpensive to assess. A device called a pulse oximeter, which you clip to your finger, can measure the proportion of hemoglobin which has oxygen bound to it. Normal, healthy readings are 95% and above.

The second noteworthy aspect of this article is that not many people even know what the carotid body is. Upon discovering this publication, some of our colleagues were candid enough to disclose they had not even heard of this important organ prior to reading this publication. And yet, it apparently degenerates and its function declines during human aging.

This brings us to the final remarkable aspect of this publication: it’s an example of the unknown unknowns that still exist. Even in this environment of accelerating scientific research, there are many things we still do not know. As such, we think it is critically important to continuously monitor the scientific literature for new data that tells us something we didn’t know, or that contradicts our current understanding of degenerative aging and how we might bring it under complete medical control.

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