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This post is an explainer to go along with this week’s It’s Okay To Be Smart video, an animated ode to the cycles that oxygen and carbon take through the biosphere. Click here to watch it.

I’ve always been fascinated with the elegant cycle that oxygen takes through our bodies and through the biosphere. While equally elegant, the biological cycle of carbon is a lot more straightforward, so I’m not going to talk about it today. My apologies to Team Carbon :)

If you ask me, more than any other, your life depends on the following two chemical equations:

What isn’t immediately obvious when you look just at the equations is why these connections exist. Where exactly do the oxygen atoms that a plant exhales come from? Out of CO2, or water? And does the oxygen we breathe end up in CO2, or H2O? There is little elegance in an equation, only simplicity. 

A beautiful recycled chain of oxygen chemistry supports a vast majority of Earth’s living universe upon its back. While it is certainly poetic in its recursive harmony, we’re not here to view it only as art. It is because of decades of scientific research that we have unlocked the beautiful secrets of the living oxygen cycle.

Take a deep breath, and join me…

When we inhale oxygen gas, it diffuses into our blood via the alveoli of our lungs. Inside our red blood cells, that dissolved gas is caged by iron-containing hemoglobin proteins that shuttle it to hungry cells throughout your body. As oxygen-rich capillaries pass near oxygen-starved cells, the double-O’s diffuse across the cell membrane. 

Inside your cells, that oxygen makes its way to the mitochondria. In the early 1960’s, it was discovered that those cellular powerhouses use diatomic oxygen, the stuff you breathe, as an “electron acceptor" during the electron transport chain, the reactions that drive ATP production in our cells. Thanks to biochemistry, we know without a doubt that the oxygen you breathe ends up as water, and not CO2. You’d never learn that from the equation.

What happens to that water? You’ll be reminded next time you go to the bathroom.

Eventually, the H2O you “release” joins with rivers and rainclouds, which deliver it back to thirsty plants. Within their veins, water molecules (some containing oxygen atoms that were once breathed in by a living creature) are delivered to chloroplasts, where they begin the next phase of their cyclical journey.

We know that photosynthesis eats up light, water, and carbon dioxide in order to produce oxygen gas and sugars. But what are the fates of those atoms? Biologists had figured out the basics of photosynthesis by the early 1800’s, but argued for decades about the detailed atomic journeys within a leaf.

In 1941, at the age of just 27, a biologist named Sam Ruben wanted to find out once and for all if the oxygen that plants exhaled came from CO2, or from H2O. Again, the equation fails to tell the story. Ruben fed plants both water and carbon dioxide that contained a heavy isotope of oxygen. Only when the heavy oxygen began as water did he find it in oxygen gas, meaning the O you breathe comes from entirely from water!

That oxygen eventually makes its way back to us, along a long and frantic journey through the atmosphere, where some of it is now entering your lungs, ready to fuel the same curious brain that now understands the cycle of the breath that feeds it. Seems like we’re finding cycles within cycles now, eh?

The living world, at least according to the oxygen cycle, seems to be a very elaborate means to trade electrons between photosynthetic and respiratory branches of the Tree of Life. Richard Feynman once said that “all life is fermentation” … perhaps he should have said all life is electricity.

Breathe that in, and stay curious :)

Whooping Cough Reaches Epidemic Proportions in California.

With more than 800 new cases reported in just the last two weeks, California has officially reached “epidemic proportions” of whooping cough (pertussis). Typically the state sees 80 to 100 cases a month. Babies are the most vulnerable.

As of June 10, there have been 3,458 cases reported to the California Department of Public Health (CDPH). That’s more than the number of reports for all of 2013, not to mention summer months are usually the worst. 

Two-thirds of pertussis hospitalizations have been in children four months or younger, and two infant deaths have already been reported. “We urge all pregnant women to get vaccinated,” CDPH director Ron Chapman says in a statement. “We also urge parents to vaccinate infants as soon as possible.” That also goes for anyone who expects to be around newborns.

The first dose of the pertussis vaccine can be given when an infant reaches 6 weeks of age. Infants who are too young to be immunized, however, remain the most vulnerable to severe and fatal cases. All pregnant women, the department urges, should be vaccinated with Tdap in their third trimester for each pregnancy — the immunity will transfer to the baby, at least temporarily. 

To be clear, whooping cough hasn’t been declared a public health emergency. When a disease exceeds anticipated levels, that’s when it’s considered an epidemic, according to CDPH’s Gil Chavez. Read the entire article here. Source: Los Angeles Times, I fucking love Science.

Merit-Ptah circa 2700 BCE

Art by J Bea Young (twitter, tumblr)

Merit-Ptah is the first woman known by name in the history of science.  Little is known of her life, but according to the tomb her son created for her in Egypt, Merit-Ptah was “the chief physician.”

A handful of physicians are known by name from this early period and there is some debate over the exact timeline.  Merit-Ptah’s life likely overlapped with that Imhotep, the man most often considered the first named physician in history.  Another male physician, Hesy-Ra, is believed to have lived at around the same time as Merit-Ptah and Imhotep.  Peseshet is sometimes named as the first female physician, but she is likely at least a generation younger than Merit-Ptah, Imhotep, and Hesy-Ra. 

Peseshet was referred to as the “lady overseer of the female physicians” during the Fourth Dynasty of ancient Egypt.  This shows there were a number of female medical professionals working in Egypt 4,600 years ago.  Peseshet is believed to have been involved in gynecological and obstetrical training at the ancient Egyptian medical school at Sais.  An inscription at Sais gives insight to the training of early medical practitioners: "I have come from the medical school at Heliopolis, and have studied at the woman’s school at Sais where the divine mothers have taught me how to cure disease.”

How Our Brains Store Recent Memories, Cell by Single Cell Findings may shed light on how to treat neurological conditions like Alzheimer’s and epilepsy

Confirming what neurocomputational theorists have long suspected, researchers at the Dignity Health Barrow Neurological Institute in Phoenix, Ariz. and University of California, San Diego School of Medicine report that the human brain locks down episodic memories in the hippocampus, committing each recollection to a distinct, distributed fraction of individual cells.

The findings, published in the June 16 Early Edition of PNAS, further illuminate the neural basis of human memory and may, ultimately, shed light on new treatments for diseases and conditions that adversely affect it, such as Alzheimer’s disease and epilepsy.

“To really understand how the brain represents memory, we must understand how memory is represented by the fundamental computational units of the brain – single neurons – and their networks,” said Peter N. Steinmetz, MD, PhD, program director of neuroengineering at Barrow and senior author of the study. “Knowing the mechanism of memory storage and retrieval is a critical step in understanding how to better treat the dementing illnesses affecting our growing elderly population.”

Steinmetz, with first author John T. Wixted, PhD, Distinguished Professor of Psychology, Larry R. Squire, PhD, professor in the departments of neurosciences, psychiatry and psychology, both at UC San Diego, and colleagues, assessed nine patients with epilepsy whose brains had been implanted with electrodes to monitor seizures. The monitoring recorded activity at the level of single neurons.

The patients memorized a list of words on a computer screen, then viewed a second, longer list that contained those words and others. They were asked to identify words they had seen earlier, and to indicate how well they remembered them. The observed difference in the cell-firing activity between words seen on the first list and those not on the list clearly indicated that cells in the hippocampus were representing the patients’ memories of the words.

The researchers found that recently viewed words were stored in a distributed fashion throughout the hippocampus, with a small fraction of cells, about 2 percent, responding to any one word and a small fraction of words, about 3 percent, producing a strong change in firing in these cells.

"Intuitively, one might expect to find that any neuron that responds to one item from the list would also respond to the other items from the list, but our results did not look anything like that. The amazing thing about these counterintuitive findings is that they could not be more in line with what influential neurocomputational theorists long ago predicted must be true," said Wixted.

Although only a small fraction of cells coded recent memory for any one word, the scientists said the absolute number of cells coding memory for each word was large nonetheless – on the order of hundreds of thousands at least. Thus, the loss of any one cell, they noted, would have a negligible impact on a person’s ability to remember specific words recently seen.

Ultimately, the scientists said their goal is to fully understand how the human brain forms and represents memories of places and things in everyday life, which cells are involved and how those cells are affected by illness and disease. The researchers will next attempt to determine whether similar coding is involved in memories of pictures of people and landmarks and how hippocampal cells representing memory are impacted in patients with more severe forms of epilepsy.

Pictured: Human neuron showing actin formation in response to stimulation. Michael A. Colicos, UC San Diego

"I try to conserve my energy." “How do you mean?” “Everybody is always wasting their energy on being against other people. They like to say ‘I’m against this,’ or ‘I’m against that.’ I say a lot of prayers when I wake up in the morning. But one of the prayers I always say is: ‘God, please send me someone that I can help today.’”

David Wong (via cracked)