Where is my spleen?

Where is my spleen?

Galen considered the spleen to be a source of one of the four bodily humors, specifically the black bile associated with irritable, melancholic cranks. “Splenetic” describes a person affected by ill humor or irritability, although the first book of the Talmud (Berakoth 61) says the spleen “produces laughter” (and “the lungs absorb all kinds of liquids”, and “the liver is the seat of anger”).

The new research entitled “Identification of Splenic Reservoir Monocytes and Their Deployment to Inflammatory Sites” and published at Science Mag shows that the spleen is a reservoir for monocytes, and that in the event of a serious trauma to the body like a heart attack, gashing wound or microbial invasion, the spleen will disgorge those monocyte into the bloodstream.

From the abstract:

A current paradigm states that monocytes circulate freely and patrol blood vessels but differentiate irreversibly into dendritic cells (DCs) or macrophages upon tissue entry. Here we show that bona fide undifferentiated monocytes reside in the spleen and outnumber their equivalents in circulation. The reservoir monocytes assemble in clusters in the cords of the subcapsular red pulp and are distinct from macrophages and DCs. In response to ischemic myocardial injury, splenic monocytes increase their motility, exit the spleen en masse, accumulate in injured tissue, and participate in wound healing. These observations uncover a role for the spleen as a site for storage and rapid deployment of monocytes and identify splenic monocytes as a resource that the body exploits to regulate inflammation.

The role of spleen in the production of antigens is well known. It has been found that the brain has the capacity to stimulate the production of antigen specific antibodies by its parasympathetic autonomic output.

But spleens are rather sensitive organs and can rupture during contact sports or accidents, at which point the risk of hemorrhaging is so that a surgical removal is the best choice. The new findings doesn’t counter this practice, but suggest that the loss of the organ is more than a mere “inconvenience”, and could help explain previous reports showing an enhanced risk of early death among people who have undergone splenectomies. In 1977 researchers compared a group of WW2 veterans who had had their spleens removed as a result of battle injuries with a similar size sample of veterans who had suffered other war injuries but had kept their spleens. The splenectomized men, the researchers found, were twice as likely to die of cardiovascular disease as were the veterans in the control group.

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A popular, famous and often-quoted misunderstanding lies on the very basis of the Evolution theory: “a species evolves into another species by random mutation“. This idea, repeated in many magazines and blogs and friends-talks, is simply and fundamentally wrong!

The bad side is that it’s sometimes used to distort the real mechanism of Evolution and to push Theistic Evolution or Intelligent Design ideas. The good side is that the concept is easy to understand and get it right.

Species are formed by *selection*, most often natural selection. Natural selection, albeit myopic, is not random: since individuals are slightly different, their chances of reproduction are also slightly different, so on average and after a big number of generations the most favorable features will get preserved.

Those differences were caused by mutations, indeed. However, mutations happen in a number larger than many people realize: many of them create differences that are not perceptible; other mutations don’t even create any differences (silent mutations); other mutations create bad cells that are killed right away; and some other mutations are immediately corrected by the DNA replication process itself.

In fact, it is possible to find different pairs of DNA threads between identical twins: over the course of life, cells multiply and mutations (mostly harmless) will occur. Even inside *you* it’s possible to find pairs of cells with different DNA threads. The difference is irrelevant but shows how mutations happen all the time and without purpose.

We *can* say DNA mutations are random because they are unpredictable and non-deterministic. What makes evolution work is the subsequent process of selection, eliminating harmful mutations and increasing the chances of favorable mutations (interestingly, sometimes letting some irrelevant or so-so mutations pass by, giving rise to biological variety, but that is another story).

The analogies with pattern recognition are flawed because they ignore all the other mutations that were not success full. It restricts itself to a final picture, like interviewing the guy that played a pair of dice and got double-sixes 10 times in a row.

If we could only see the final result, certainly would be hard to believe that the process of throwing dice was really random. It would make sense to think that perhaps there was a pattern, so complex we just couldn’t figure out. That something somehow was making sure the double-sixes kept coming, round after round.

But if you could see the hundreds of failed attempts to get double-sixes, all those times where other players got a 2-5 or 3-3 and got kicked out of the competition, then the whole picture gets clear: it was simply random.

Are the actions of throwing our arms in the air when we win and slumping our shoulders when we lose innate or learned by watching others?

Researchers took photos of 108 athletes winning and losing judo matches during the Athens Olympic Games in 2004, and the subsequent Paralympic Games. Judokas were divided in three groups: sighted, born blind, and acquired blind.

They found that the sighted and sightless athletes behaved in almost exactly the same ways. The winners tilted their heads up, smiled, lifted their arms, clenched their fists and puffed out their chests, while slumped shoulders and narrowed chests were the hallmarks of losers.

The stances were also remarkably consistent between men and women, and between contestants from every part of the world. The athletes’ culture has only a very small effect on their body language.

The only small difference was that sighted athletes from the paragons of individualism – Europe and North America – showed weaker responses to failure. They chests still narrowed and their shoulders still slumped but to a lesser extent. Their blind peers showed slightly stronger shame behaviours while those that were always blind were even more apparent.

That strongly suggests that the sighted fighters were masking their shame in accordance with their national values. Western culture, with its emphasis on self-assertion, tends to frown on public displays of shame, while more collectivist nations like Japan or China view shame as an appropriate and socially valued response. Their respective athletes behaved accordingly.

The authors believe physical expressions of pride may have evolved as a way of signalling the winner’s success to the rest of society, thereby boosting social status. Similarly, the response to shame would show an aggressor that the loser accepts their inferiority, helping to avoid further conflict. The researchers also point out that such displays closely resemble dominance and submission displays in primates.

“The ability to signal these kinds of behaviours reinforces hierarchies and social networks.”