THE BRAIN IS A SEA CREATURE

India Ink drawing

A human being is essentially a sack of sea water with self-contained creatures living inside that we call “organs.”  There are two ways of circulating the sea water so that the organs survive.  One is piped and carries little discs full of red oxygen, everything pumped by a heart attached to lungs which open at the top to the general atmosphere where the oxygen is.  The lung-pump is called a diaphragm and is a sheet across the entire mid-body, an internal tide-maker acting inside a ribbed calcium shell structure arching in a bone dome above the diaphragm.

Most of the other sea creatures have to do with taking in food, treating it, and throwing out the residue.  Also, a side pouch for making replicas, small fetal humans.  But on top is a semi-sequestered creature, twinned, that lives in a bone chamber and sorts out the coded electrochemical messages from small sensitive creatures called eyes, ears, tongues, nose, and maybe as many as 200 specialized one-celled organisms throughout the tissues of the entire body.

Everything must stay wet to work.  Alongside the piping of the blood vessels are other fluids.  They are like liquid bread: all the same basic recipe but varied according to need with inclusions and subtle chemical differences.  Like all the rest of the body, to survive the lymph system must stay within the stream-banks of limits, which means that the inclusions and proportions must be constantly renewed and filtered.  

Now I’ll cheat in a politically incorrect way by quoting Wikipedia.  Thanks to the uncredited person who wrote this about basic lymph:

“Lymph is the fluid that circulates throughout the lymphatic system. The lymph is formed when the interstitial fluid (the fluid which lies in the interstices of all body tissues) is collected through lymph capillaries. It is then transported through larger lymphatic vessels to lymph nodes, where it is cleaned by lymphocytes, before emptying ultimately into the right or the left subclavian vein, where it mixes back with the blood.

“Since the lymph is derived from the interstitial fluid, its composition continually changes as the blood and the surrounding cells continually exchange substances with the interstitial fluid. It is generally similar to blood plasma except that it doesn't contain red blood cells. Lymph returns proteins and excess interstitial fluid to the bloodstream. Lymph may pick up bacteria and bring them to lymph nodes, where they are destroyed. “Metastatic cancer cells can also be transported via lymph. Lymph also transports fats from the digestive system (beginning in the lacteals) to the blood via chylomicrons.

“Lymph has a composition comparable to that of blood plasma, but it may differ slightly. Lymph contains white blood cells. In particular, the lymph that leaves a lymph node is richer in lymphocytes. Likewise, the lymph formed in the human digestive system called chyle is rich in triglycerides (fat), and looks milky white because of its lipid content.”

“The word lymph is derived from the name of the ancient Roman deity of fresh water, Lympha.”

First we learned all about the genome; then the epigenome which can turn individual genes on or off in response to the environment; then the connectome which is the pattern of connection of brain neurons that responds to particular modes and tasks, and then the microbiome.  “The human microbiome (all of our microbes' genes) can be considered a counterpart to the human genome (all of our genes). The genes in our microbiome outnumber the genes in our genome by about 100 to 1.”

Now we begin to learn about the glymphatic system, which is a specialized part of the lymph system in the brain.  It’s in the interstitial spaces between cells and sometimes in a channel parallel to the blood system.  It’s the stuff that washes through the brain at night to remove the day’s debris, and it interests Alzheimer’s researchers because it should be removing amyloids.

But I’m interested in where all this fluid in the head comes from, cascading down through the sinuses, along the bone of skull both inside and outside under the skin, becoming mucus and tears and snot, pooling in the sinuses, running out the nose, draining through the pharynx.  What makes it move, aside from gravity and muscle contractions?  It’s so minute and complex that I don’t quite get it yet.  

But two important concepts seem to be the “parenchyma” which is whatever tissue is part of a working “sea creature” organ (such a basic term that it’s used for plants as well); the ependyma; and the “choroid plexus, which is a plexus of cells that produces the cerebrospinal fluid in the ventricles of the brain. The choroid plexus consists of modified ependymal cells.”  These little cells not only excrete the fluid, but also are equipped with cilia (moving hairs) that push it.  There are four “choroid plexuses”, one for each brain ventricle.  “The ventricles of the brain are a communicating network of cavities filled with cerebrospinal fluid (CSF) and located within the brain parenchyma.” 

Since I don’t have hydrocephalus (for which I am grateful), why would I pay any attention to all this stuff?  It turns out to be related to eye problems.  In a world where even an MD can’t offhand tell the difference between an optometrist and an opthalmologist, this research about the glymphatic system of the eye is invisible.  http://iovs.arvojournals.org/article.aspx?articleid=2572611  

I am very aware that if things are going wrong with my eyes, the retina swells and blurs print.  My glaucoma scores (pressure inside the eyeball) are rising and that also seems related. 

Messing around in the research protocols, the scientists injected India ink in “paravascular spaces around the central retinal artery and vein, whereas the lumens of these vessels remained unlabeled.  The deposits were located between collagen fiber bundles lining a slit-like space.”

India ink injected in optic nerves!  What an opportunity for dark poetry!  (Some of the research was done on dead humans.)  I’ll give it a try:

Of course, as usual, India ink 

is a misnomer

since it was invented by the Chinese

In the neolithic time 

of cereal domestication

when the people learned to make bowls

And lamps so that 

India ink is made from lampblack, 

a fine soot,

applied to paper

with a needle, injecting 

the eye 

with the heroin of ideas

so the brain

knows

what to make of all this and can leave a map 

on a scroll

for times that prefer

soft brushwork.

May I have more, please?

But not too much.

The tentacles of my eyesight want to grasp you.

Not crush you.