Breath: Divine Gas in a Smart Body

We use the word breath most often to refer to the air we pull in to and pump out of our lungs (or to the action of doing so) as in “Take a deep breath.” But we also give the same word loftier qualities in phrases such as “the breath of life” and in practices like yoga that emphasize breath awareness as a source of health and peace. Other traditions and languages have similar words for breath in both these ordinary and spiritual senses, such as Latin spiritus, Hebrew ruach, and Chinese qi.

breath spirit (soundofheart.org)

soundofheart.org

But what about the breathing body itself? Unless we are wheezing or short of breath and a doctor checks us out, we usually take the smooth coordination of our lungs, diaphragm, membranes, blood cells, as unremarkable compared to the loftier significance of breath that we might hear about in yoga class or worship service.

We might refocus our wonderment for a moment. The air is, when you come down to it, just a mix of gasses, but our body’s ingenious respiration of them is something to appreciate.

We breathe in air because, as we know, it contains one gas that we must have: oxygen. Less familiar, though, is the step-down system that has evolved to make the most of the fact that, like all gasses, oxygen spreads out from wherever it is most densely packed to where it is less so. Thanks to the step-down process and our blood stream, we move oxygen from the air outside of us to everywhere it has to go inside us, which is to our several trillion—that’s 000,000,000,000—cells.

Why oxygen? Its electrons are arranged in such a way that it interacts eagerly and often with other elements. It’s a potent extrovert. Our cells may get their nourishment from the food molecules they take in but not unless they also have oxygen handy to break the food molecules down. That would be like our eating dinner without having any stomach acid to digest it. No nourishment. Without oxygen, cells go hungry.

But a little oxygen goes a long way. That helps make the step-down process possible. The numbers surprised me. For starters, only about twenty percent of the air that we breathe is oxygen. The rest is nitrogen and a percent or two of other gasses. And of that oxygen that we do take into our lungs, we actually use only about a quarter of it. The rest goes out again when we exhale.

Once it is in our lungs, oxygen must get across the thin lung membrane to the blood stream that will move it around the body. The oxygen in the lung is much denser than whatever oxygen is left in the blood that is returning from the cells through the veins. So the new oxygen spreads easily across the membrane—stepping down—to the oxygen-depleted blood where it hooks up with empty hemoglobin molecules in the blood cells.

As this convoy of oxygenated blood flows near, say, our fingers, the oxygen detaches from the hemoglobin, steps down across the membrane of the cell itself (because there is less oxygen inside), and goes to work on the food particles.

In the process, extrovert that it is, oxygen combines with the unusable carbon dioxide, crosses the cell membrane back out to some empty passing hemoglobin, gets off at the lungs, and then back out to air. Like taking the empty bus back home at the end of a long day.

I argue for the wonderment of a distribution system that pulls in air-borne oxygen in an endless rhythm and is arranged so that the oxygen disperses itself across strategic membranes and loads itself on to the blood for transport to a million million cells that it will help nourish, after which it returns the way it came in. Our stunning respiration makes oxygen look good—even divine.

 

Cyanobacteria: R-E-S-P-E-C-T

We owe cyanobacteria our respect. And they might deserve our fullest gratitude as well if it weren’t for one nasty trait.

For starters, if we are to believe that our elders deserve respect, cyanobacteria certainly qualify. They date back 3.5 billion years, almost to the earliest signs of life. But they are not only old. They are interesting, they seem uncomplicated, and they are powerful and successful. They are single-celled, though many live connected to each other in colonies and filaments. They are primitive; unlike the cells of younger species, they have no nucleus. And they have not only survived all this time; they have thrived. Their species number at least two thousand that have been described and at least twice that number in total. Most are blue-green—“cyan”—but their various pigments also account for the colors of pink flamingoes and the Red Sea.

cyanobacteria (https-::i.kinja-img.com:gawker-media:image)

(gawker)

Cyanobacteria gave us oxygen—and continue to do so. For the first two billion years after the earth’s formation 4.5 billion years ago, the atmosphere contained almost no oxygen. But the blue-green pigment in cyanobacteria is a mix of green chlorophyll and a blue pigment both of which turn sunlight and carbon dioxide into sugary energy for the cell. Oxygen is the waste product—and early cyanobacteria produced so much of it for so long that it accumulated in the atmosphere and eventually supported larger, more complex cells, including ours.

Just as important, atmospheric oxygen spawned an ozone layer that reduced the lethal levels of the sun’s ultraviolet radiation. It’s that filtering that allowed early plant and animal life to finally move on to land after three billion years in the water.

Cyanobacteria made plants themselves possible by becoming part of them. Some other early bacteria engulfed cyanobacteria and then, because of cyanobacteria’s efficient energy production, turned them into one of the pieces of organic machinery enclosed within a plant’s cell. We see them today as the greenery of plants—the chloroplasts—that power them and keep them reaching for the sun.

Cyanobacteria are handy with another gas in addition to oxygen. They convert nitrogen in the atmosphere into a form that plants and animals need for such building blocks as proteins and DNA. Natural nitrogen fertilizer.

pond scum wikipedia

(Wikipedia)

Cyanobacteria often go by the name of blue-green algae. But they’re not algae. Algae is an informal term for many water-borne organisms that contain  chlorophyll but lack stems, roots, or leaves. Seaweed is algae. Cyanobacteria are bacteria—simple cells, often strung together, without nuclei.

As for that one nasty trait, cyanobacteria can kill you. Especially in freshwater ponds and lakes, blooms of cyanobacteria looking like blue-green paint slicks may be toxic to nerve and liver systems, depending on the species. The poisons may work their way into the food chain, pets may eat them, water-skiers may absorb them. The result can be respiratory failure, Parkinson’s, ALS. Not often, but too often. Respect.

Reading about cyanobacteria on the Internet, you get a glimpse of a life-form from an inconceivably ancient world that is woven throughout the air, water, and soil of our own time. We are in their debt for the breath we take, the food we eat, for our living on solid ground.  We stand on their countless, tiny shoulders.

Stem Cells: How To Build and Maintain Bodies, Including Plants

Until recently, I didn’t know much about stem cells except that they produced other kinds of cells and that the medical research on them was controversial. In the context of the history of life, it turns out, their importance is as fundamental as you can get.

It took more than a billion years for the first cell with a nucleus to come together. Since then, the only reliable source for a new cell has been another cell. Every cell is an offspring. True for plants as well as animals.

An embryonic stem cell (Wikipedia)

An embryonic stem cell
(Wikipedia)

But while cells are specialized for one task or another, they are not always very good at dividing and reproducing. Muscle cells, blood cells, and nerve cells don’t reproduce at all. Other cells in the body divide only under some circumstances or only a limited number of times.

But reproduction is the stem cell’s specialty. When it divides, it produce another stem cell, ready for the next round, along with a muscle cell or blood cell or nerve cell or a cell of another organ. It looks the part for such flexibility—blob-like, unstructured, not committed until needed.

Stem cells are stationed throughout the body, small groups of them in each organ, like local hospitals on call to repair the sick and damaged. They are a profound piece of bodily engineering, a design for the long-term, like a futuristic car that carries little 3-D printers throughout the engine and chassis to create new parts and replace the old parts automatically.

In human embryos, in contrast to adults, stem cells literally build the body. When an embryo is only a few days old, its stem cells begin to form all—all—of the specialized cells needed in a body, some 200 of them.

In this root tip, the number 1 marks the relatively unstructured stem cells in the meristem. (Wikipedia)

In this root tip, the number 1 marks the relatively unstructured stem cells in the meristem.
(Wikipedia)

Plants have stem cells too. Located near the tips of the roots and stems in a layer called the meristem, plant stem cells divide into both specialized cells for the plant and additional stem cells. Stem cells are, in other words, the place where a plant grows.

One of the wonders of any living thing is the sheer variety of its parts, the inventory of its tubes, organs, fluids, surfaces, protrusions, electric circuits and rigid pieces. As we pause to appreciate this profusion, sing the praises of the smudgy cell that creates and repairs them all.