Blood (3 page)

An average adult has about five litres of blood, representing about 7 percent of their body weight. Blood, like just a few other body parts, such as hair, fingernails, and toenails, is always replenishing itself. Dying and growing back. And like hair and nails, blood will regenerate if you lose it intentionally or accidentally. The bone marrow constantly produces red blood cells, white blood cells, and platelets. And the body can replace donated plasma within hours. But beware: not too many body parts work this way. Lose 'em once, and — like an arm or a leg — they're gone forever. But you can afford to lose up to about 40 percent of your blood and still survive, if you don't lose it too quickly.

There are various types of blood. One common grouping is A, B, AB, and O. And then you can be Rhesus (Rh)-positive or Rh-negative. You have a certain blood type, and that blood type matters. Most blood types cannot be mixed with other blood types. If they are, the person receiving mismatched blood could die.

It is humbling to contemplate all that blood does. In addition to lugging oxygen to all bodily tissues, blood delivers nutrients such as amino acids, fatty acids, and glucose. It carries away waste such as carbon dioxide and lactic acid, detects and attacks foreign invaders, coagulates to stop bleeding, regulates body temperature, transports hormones, detects tissue damage, and is responsible for hydraulic functions — an oddly formal term for the task of blood during sexual activity. I imagine blood as a happy workaholic, humming away and in a state of constant calisthenics as it nourishes us, lifts us into arousal, does battle with invaders, and replenishes itself.

Blood, like human identity, is ever shifting. Just when it has acquired a certain personality or chemical balance, it gets thrown into turmoil and must regain equilibrium. It can manage stress, but only so much. I imagine blood as the planet earth, and all of the bodily reactions to disturbances — be they sugar or alcohol — as gravitational forces, pulling everything back to the ground. You're in trouble when your gravitational forces don't work, or when you've overdone it so much that your body just can't cope. That, by my way of thinking, is like shooting a rocket through space with no way of bringing it back down to earth.

Travelling like an indefatigable river along its intertwined circulatory systems, passing through the heart and lungs and feeding the rest of the body, blood keeps us alive and has forever held us in its debt. To it we owe our daily health. To it we pay ransom — insulin injections, chemotherapy treatments, bone marrow transplants, the use of clotting factors — when order turns to disorder in our arteries and veins. And from it we build a frame to envisage our own humanity. We let it run from our veins as a gift to others in failing health. And if we believe in a superior being, we give it up as an offering so that we may go on living.

WHAT WE NOW KNOW
about blood seems all the more astounding when we think about where we have come from. For some two thousand years, philosophers and physicians imagined blood as one of the fundamental characteristics of our body and soul. We linked it to the spring, the air, and the liver.

Thanks to the theories of figures such as Hippocrates, in 460
BCE
, and Galen, in about 200
CE
, we came to believe that sickness arose as a result of disequilibrium between four key parts (or humours) of the body: blood, yellow bile, black bile, and phlegm. Hippocrates inspired the Hippocratic oath and is often referred to as the father of modern medicine. Claudius Galen proved the presence of blood in the arteries, and argued that arteries and veins are distinct and that the liver has a key role in blood production. “The liver is the source of the veins and the principal instrument of sanguification,” Galen wrote in
On the Usefulness of the Parts of the Body
.

Galen argued that the preponderance of one particular humour went so far as to determine a person's basic personality type. One might be sanguine, choleric, bilious, or melancholic — words and concepts that continue to resonate with us today. Blood, for example, was said to quicken the spirit, and the adjective “sanguine” derives from the old French word
sanguin
and from the Latin
sanguineus
(meaning “of blood”). It refers to a person who is courageous, loving, and optimistic, especially in difficult situations. The
New Oxford American Dictionary
offers the following definition of “sanguine” in the context of medieval science and medicine: “of or having the constitution associated with the predominance of blood among the bodily humours, supposedly marked by a ruddy complexion and an optimistic disposition.”

But too much of any humour would create a dangerous disequilibrium in both temperament and health — the elusive “mind-body” balance we still search and long for today. Traditional Islamic medicine and the Ayurveda medicine of ancient India suggest food and diet as one means to correct imbalances of the humours.

Another was the technique of bloodletting, or phleb­otomy. In retrospect, it is sobering to imagine how many thousands of patients have died from bloodletting or its complications. I, for one, hate having my blood played with or withdrawn and feel grateful in the extreme for Louis Pasteur and Robert Koch, both nineteenth-century scientists who demonstrated that inflammation results from infection, thus obviating any need for bloodletting.

Bloodletting is still practised in a few ways. We donate blood, have it withdrawn for laboratory tests, and use it to treat problems such as polycythaemia (an abnormally high concentration of hemoglobin in the blood) and hemochromatosis (a hereditary disorder in which excess iron is absorbed through the gut and deposited in tissues).

For thousands of years, physicians have used leeches as a bloodletting device. They, like some other animals, such as mosquitoes, lampreys, and vampire bats, have figured out that sucking other animals' blood is an effective shortcut to a rich, nutritious meal. I wonder who, in medical cultures in ancient Egypt, Greece, and India, came up with the bright idea of ushering leeches onto human skin for the purposes of bloodletting. Someone must have stepped back and muttered, “But there must be a use for this worm that annoys me so.”

Leeches still have a role in modern medicine, particularly in reconstructive or plastic surgery. They dilate the blood vessels and prevent the blood from clotting, and are especially useful after surgery in promoting the flow of venous blood. They have proved useful in the re­attachment of body parts such as fingers, hands, toes, ears, noses, and nipples. Because veins have thin walls, they can be hard to stitch together in surgery. Until the body figures out how to do so again, leeches secrete an enzyme that helps move the blood into the thin and sometimes damaged veins of reattached body parts. They are energetic little devils. A leech can suck more than three times its body weight in blood.

It may be troublesome to imagine a leech — which is basically a bloodsucking worm — attaching itself to your body. But other forms of traditional phlebotomy jump out as being far more invasive, and potentially lethal. I would take a leech over a human bloodletter, any day! Clearly, others feel the same way. Eric M. Meslin, associate dean for bioethics at the Indiana University School of Medicine, told me that while he was visiting the Spice Bazaar in Istanbul in April 2013, he came across a vendor who conducted a brisk business selling leeches. Identified on his storefront as “Prof Dr. Suluk,” the man sold leeches for purposes such as migraines, cellulite, low back pain, eczema, and hemorrhoids.

In 400
BCE
, the Greek historian Herodotus recommended cupping (the use of a partial vacuum to draw blood) as a means to promote appetite, digestion, and menstrual flow, and to resolve problems such as headaches and fainting. If blood is removed from behind the ears, he said, it brings about a natural repose. Other spots from which blood has traditionally been let include the knees and elbows. Bloodletting was certainly not limited to one cultural, religious, or geographic group. In addition to the Greeks and the Romans, bloodletting was carried out in Islamic cultures (for example, the Arab queen Zenobia killed King Jothima Al Abrash in this manner). Hindus practised it too.

Bloodletting also entered into ancient Jewish traditions. As Fred Rosner wrote in 1986 in an article for the
Bulletin of the New York Academy of Medicine
, in the third to the fifth centuries
CE
, the Sages of the Babylonian Talmud held that a learned man should not live in a town that had no bloodletter. Bloodletting was recommended for headaches and plethora (an excess of blood).

The medieval scholar and rabbi Maimonides wrote about the benefits and hazards of bloodletting, but not all Jewish writers believed in the practice. The Old Testament contains, in Leviticus, a prohibition against cutting into the skin. Maimonides said that before bloodletting, a patient should recite a supplication to God for healing, and that after treatment concluded that patient should say, “Blessed art Thou, Healer of the Living.”

Over the years, many famous people have died of bloodletting. Charles II, king of England, Scotland, and Ireland from 1660 to 1685, should have been inspired by his own family history to pay close attention to the safeguarding of his own blood. After all, his own father, Charles I, was beheaded in 1649 on the charge of treason. Some of the king's followers dipped their handkerchiefs in his blood. Oliver Cromwell, the revolutionary leader, permitted the king's head to be sewn back onto his body so that his family could mourn properly after the execution. Nonetheless, some thirty-six years later, his son Charles II found himself ill at Whitehall Palace in London. Known as “the merry king” for his philandering, Charles II took to his bed one night with a sore foot. The next day, a barber shaved his head and the bloodletting began. In addition to enduring purging, mustard plasters, red-hot irons, and enemas of rock salt and syrup, Charles II had twenty-four ounces of blood withdrawn from his arms. He suffered a seizure and died.

Napoleon survived a bloodletting and is known to have described medicine as “the science of murderers.” Mozart is thought to have died of shock from severe bloodletting, and George Washington lost his life a day after more than 2.3 litres of blood were taken from him, purportedly to help him cope with a cold and hoarseness.

It would be easy to mock bloodletting as pseudo-­medicine that hurt or killed thousands of people over thousands of years, and whose widespread use has come to a halt only in the past century or so. But that would be an easy target. It is not hard to imagine the peals of laughter and squeals of disbelief that people might share in one hundred years when they analyze today's medical practices. They will surely shake their heads and say, “What were they thinking?” We will always be in a state of evolution with regard to the perceptions about how our bodies work and how they can be cured of illness and disease.

To me, the interesting thing about bloodletting is how thoroughly it was interwoven with our belief systems, and how long it endured. For two millennia, we coasted with the unassailable idea that a healthy body and a healthy mind should not be burdened by too much blood. In our minds, we removed its impurities to improve our physicality, along with our moods and emotions, by letting our blood run. And ever since, we have been obsessed with the idea of balancing our minds and bodies and improving the composition of our blood. For thousands of years, to spill our own blood in the name of medicine, we used every manner of knife, quill, tooth, lancet, and scalpel. We could have filled rivers and lakes with all the blood we have voluntarily spilled. We did so because of our belief systems. We let our blood run because we had imaginations.

We are always looking for ways to distinguish ourselves from other animals. Let me add one more point of comparison. Can you think of any other animal that cuts itself, or others, to satisfy the cravings of its soul? Other animals will attack if they need food, or run to avoid being eaten, but generally they have the good sense to leave their own blood alone.

THE SEVENTEENTH-CENTURY BRITISH ANATOMIST
William Harvey — physician to King Charles I — refuted thousands of years of medical thinking when he proved that blood circulates in the body and is pumped by the heart. He dissected live animals to establish his theory. It seems barbaric today, but Harvey had no other means at his disposal to advance his theories. As Thomas Wright notes in his book
Circulation: William Harvey's Revolutionary Idea
, in the early seventeenth century, “Men could no more see blood coursing around their arteries and veins, going to and from the heart, than they could perceive that the earth was spinning round.”

In 1628, Harvey confronted and shocked his doubters at the University of Altdorf in Nuremberg. Dressed in a white gown and his head covered with a white bonnet, the diminutive physician instructed porters to affix a live dog to a dissection table, immobilizing it and tying its jaws shut to prevent barking. He plunged a knife into the animal's thorax, exposed its heart, and indicated the rising and falling of the organ. When the dog's heart was in contraction, Harvey severed an artery. The blood spewed forth, showering the closest spectators, several feet away. Thus we finally learned the basics of blood circulation. Understanding this concept opened up the long and painful path toward blood transfusions.

In the mid-1600s, doctors in France and England competed madly for the honour of carrying out the first blood transfusions. Dogs were transfused with the blood of other dogs, and eventually humans were transfused with the blood of calves and lambs. While some of these procedures did not lead to fatalities (possibly because little or no animal blood actually managed to enter the human bloodstream) and were deemed a success, others did result in death.

One of the earliest documented transfusion attempts involved a French physician named Jean-Baptiste Denis, who grabbed a man named Antoine Mauroy off the streets of Paris in 1667 and attempted to calm his agitated mind by forcefully transfusing the blood of a calf into his veins. The physician believed that the mildness and freshness of the gentle animal would, by entering the patient's bloodstream, affect his personality. We now know that a human being is likely to have a severe or fatal reaction to the blood of any animal, because the human body rejects the foreign substance. Mauroy died after a few attempts. His wife brought a complaint to the authorities. Denis and his colleagues countered that the patient's wife had poisoned her husband. A French court eventually exonerated the doctor and charged the victim's wife with murder. She disappeared from the records, and it is likely that she was executed.