In this book, I will approach blood from five different angles — all of which fascinate me personally and fuel my own obsessions. I will touch from time to time on the physical properties of blood, and on its intersections with medicine, both ancient and modern. Beyond how blood functions in the body, I am interested in how it weighs on the human mind, and how it influences our perception of who we are, to whom we belong, and how we experience our own humanity.
In chapter one, I will explore how our own notions of blood have evolved over thousands of years, share an overview about its nature and functions, address some of the different ways that blood defines men and women, and ponder how our own blood betrays us.
Chapter two will investigate how blood reflects our deepest notions of truth, honesty, and morality. When blood spills, we demand — in literature and in reality — that it exert a downstream effect. There should be consequences, which satisfy us morally. You can’t just go spilling blood without cause or effect. Changing the nature or composition of our blood, as well as how we give and receive it, sometimes raises not a single eyebrow, and at other times it incites trenchant judgement. Our response to alterations of blood points to some of our most enduring values, so chapter two will ponder some of the more provocative aspects of changing our blood in medicine and in sport.
A meditation on blood and belonging will form the essence of chapter three. What does our blood tell us about what we are supposed to do, to whom we belong, and the rights that we enjoy or are denied? How do we use blood to differentiate between groups of human beings, and what does that tell us about ourselves?
In chapter four, I will explore the idea that the exercise of power, control, and public spectacle depends on bloodshed. Where you find some people dominating others — to make a revolution stick, or to quash one, or to vilify enemies, or to demonize an entire minority group — you will have no need of hound dogs to find a trail of blood.
The final chapter will delve into how blood offers up our deepest secrets and revelations. Who did we used to be, before we tried to fool the world and acquire an entirely new personality and public identity? Why and how have people slid from one entrenched identity to another? What truths, including the inconvenient ones that can indict us in a court of law or in the court of family judgement, lie in our blood? To whom are we most distantly related?
Blood reveals us and protects us. It’s a curse, and it can be a sign. In Exodus, the blood of the lamb protects the Israelites from the avenging Angel of Death sent to kill the first-born sons of all Egyptians, who are responsible for the enslavement of the Jews. By smearing lamb’s blood on doorposts, the Hebrews signify their innocence and their homes are passed over.
Blood can also be a gift. At the Last Supper, Jesus tells his disciples that their wine is his blood and instructs them to drink it in memory of him — a practice and a belief that are still part of the Catholic Mass (the Eucharist, for Anglicans; the Holy Communion, for other Protestants). In religious lore, saints have shown stigmata — bleeding hands that mimicked Christ’s wounds from being nailed to the cross.
Blood is not just a symbol in religion. It’s a symbol in literature. In storytelling, it is integral to the very way we speak and express ourselves. Iambic pentameter, used in much poetry and in Shakespeare’s plays, is said to best capture the rhythm of human speech. Its emphasis — an unstressed syllable followed by a stressed one, da-DUM, da-DUM, da-DUM, da-DUM, da-DUM — lodges in the memory and seems familiar on the tongue and to the ear. Perhaps that’s because it is also the sound of the human heart. It is the sound of blood coursing through our bodies.
And this is where we find ourselves, when we behold great art. Right in the core of our bodies, deep in the midst of our arteries.
When I was a child, I had the fortune to have a mother, Donna Hill, who read poetry to me at bedtime. She was a kickass civil rights activist who shook her white friends and family to the core and turned her own life upside down when she fell in love with a black graduate student in Washington, D.C., and moved with him to Canada. However, at the age of three, when it was time for bed, I neither knew nor cared about those things. What I cared about was that a gentle, loving soul named “Mom” would summon all of her enthusiasm and pitch it into her nightly poetry readings. My favourite of all was her rendering of the poem “Disobedience,” by A. A. Milne, which begins like this:
James James
Morrison Morrison
Weatherby George Dupree
Took great
Care of his Mother,
Though he was only three.
There, beating alongside our pulse, are the playful, absurd, seductive sounds of the early twentieth-century British writer best known for creating Winnie-the-Pooh. Milne entered our imaginations first and foremost through our ears, by mimicking the sounds of our heart. When you read Milne’s poetry aloud, it feels as if you are swimming in your own bloodstream.
It is not just poetry that climbs into your body. In jazz and rock ’n’ roll, the driving bass beat holds the music together. The bass beat gets you dancing. You want to slide into bed with it. Forget the lyrics. The bass is where you feel the music. Deep down, in your bone marrow and in the pulsing of your blood.
OUR NOTIONS OF BLOOD have evolved over thousands of years, and our understanding of its nature and functions has shaped our ideas of ourselves. Blood acts as a mirror, reflecting the march of life, of ages and civilizations. It speaks of our beliefs and prejudices, of our potential and our limitations as flawed beings. And like all things biological, chemical, and physical — the mystery of nature — it is governed by its own set of rules and regulations. Indeed, the ways that we identify and interpret the biology of blood affect our self-concept, individually and collectively.
Blood has some four thousand components. A drop of blood the size of a pinhead is teeming with quantities of cells that seem unfathomable: 250 million red blood cells, 16 million platelets, and 375,000 white blood cells. If you can imagine blood in a test tube, separated by means of a centrifuge into its key parts, you will notice three distinct substances, each with its own colour and function. Let me quickly mention them, from top to bottom in their separated forms in our imaginary test tube.
Plasma comes on top, as it is lighter than the other key blood ingredients. Made up of about 92 percent water (water accounts for about 50 percent of our blood), it is a yellowish, straw-coloured alkaline fluid. In it, you find many dissolved solids such as glucose (or sugar); proteins such as albumin, which controls the flow of water in and out of the bloodstream; hormones such as erythropoietin; and insulin, salts, lipids, and waste products such as bicarbonate ions, amino acids, and blood cells. I liken plasma to a river, offering a delivery system for the ingredients in blood, as well as carrying products that help regulate bleeding and clotting.
It is possible to donate and receive plasma separately from other blood products. When blood is withdrawn from the body, the red blood cells, white blood cells, and platelets are separated and returned to the body of the donor, minus the plasma. Some of its key medical uses are to help people cope with bleeding or clotting disorders, recover from burns, deal with immune deficiencies, and survive complications resulting from bone marrow or organ transplants. Plasma can be stored for longer than regular blood products, and it can be frozen or dried for easy transportation. One additional advantage to plasma is that the donor’s body can replace plasma much faster than whole blood.
In the tube of blood whose parts have been spun and separated in a centrifuge, the middle of the three layers contains the white blood cells and platelets. White blood cells are pale in colour. They are also known as leukocytes or white corpuscles. They come in different varieties. The primary roles of the white blood cells are to remove waste from the blood and to fight against infection. The language used to describe white blood cells is strangely military. They are said to surround and devour bacteria. They en
gulf, digest, and destroy invading micro-organisms. One type of white blood cells — accounting for about one-third of a healthy person’s white blood cell count — is known as lymphocytes. These include helper cells, suppressor cells, and natural killer cells. The killer cells are labelled “natural” after their function, which is not to attack invading organisms but to destroy the body’s own cells that are cancerous or carrying viruses.
The white blood cells are commonly likened in our language to soldiers going to war on behalf of the nations that are our bodies, identifying, targeting, and destroying foreign invaders. The war and battle metaphors we employ — influenced by the writings of Louis Pasteur in the 1800s and reinforced by U.S. president Richard Nixon, who in 1971 signed the National Cancer Act and declared a “war on cancer” — offer one way to contemplate human biology. They certainly provide us with a method to imagine the body’s efforts to deal with disease and infection. At the same time, they are at risk of leaving us with the impression that people who succumb to illness simply did not try hard enough, and that people who overcome the same illnesses are stronger, more courageous, or have more valour. It is a striking way to refer to our own bodily processes, but there you have it.
Platelets are, with white blood cells, part of the thin middle layer separating the plasma from the red blood cells. Platelets are fragments of blood cells called megakaryocytes, which reside in the bone marrow. (All blood cell lines, including platelets and red and white cells, originate in the bone marrow.) Platelets live for a short time — only a week or so. The human body produces about one hundred trillion new platelets every day. Their function is to aid in recovery from injury. If something pierces a blood vessel, platelets stick to the damaged lining and clump together. This process aids in coagulation — a blood-thickening process that stops the body from bleeding. The clotting process begins within seconds of an injury. Standing on guard and ready to self-correct, your blood organizes itself to prevent a hemorrhage. Otherwise, copious amounts of blood could drain out of you. A simple puncture of the body, left unattended, could be fatal. You would be like a bicycle inner tube when the tire rolls over a nail, with no patching gear within reach. But your body has its own patching kit. It knows how to clot. A clot can be fatal in the wrong place and for the wrong reason: say, if it is travelling toward your lungs or brain. Then it is known as an embolism. But you want the clotting function to work perfectly and immediately when you nick yourself with a kitchen knife. To me, the platelet is the nurse or doctor in your veins, ever ready to sew you up when you have been shot.
The bottom part of the imaginary tube of blood consists of red blood cells, also known as red corpuscles or erythrocytes. Round in shape and slightly concave on each side, they are the most numerous cells in the blood. Some five billion of them exist in one millilitre of blood. I think of the red blood cell as the cell of love. In contrast to the soldiering white blood cell, and the platelet with its emergency room services, the red blood cell is your bedmate. It is all about giving. The red blood cell lives for only 120 days, but what an ardent lover it is! You should salute your white blood cells and thank your platelets, but the red blood cell deserves your love. It kisses your cells with the gift of oxygen, and it is a non-stop kisser. Your body produces millions of red blood cells every second.
In humans, the blood is red thanks to iron and hemoglobin, an oxygen-carrying protein in the red blood cells. In its appearance, blood stands alone and virtually unmistakable. How often are you wrong when you think you see blood? Thanks to the presence of iron, which is also responsible for the rusty-red beaches of Prince Edward Island, blood is bright red. No other bodily fluid or tissue resembles it. I don’t often see the colour of arterial blood in nature. The closest I have seen to blood-red is a sunlit field of poppies. The sight of flowering poppies arrests me, every time. I have to stop and stare at it. I take in a breath, and never fail to think that the field before my eyes is beautiful. Silent under the skies, teased by the wind, it resembles a vast blanket of undulating blood.
But even the colour of blood varies, slightly, and has led many people to wonder if it is blue when not exposed to oxygen. Blood is never blue in human beings, but given the way that light can strike fair-coloured skin, it can sometimes appear that way from outside the body. Indeed, the term blueblood, which means a person of noble ancestry, derives from the idea that the venous blood may seem to have a blue tint through the light skin of a person freed from the burden of having to work in the sun. Indeed, polo — a game of the very rich — is sometimes described as a blue-blooded sport. The “colour” of our blood is just one example of how we have uniquely attached meaning and metaphor to blood as a way of differentiating ourselves from others, in this particular instance as a marker of class superiority. Just as quickly as blood can elevate your status, it can denigrate you. A “bloody fool” is an idiot — perhaps dirty, and possibly blood-spattered. The “bloodthirsty masses” are the last thing from genteel. On the contrary, they have empty bellies and, lacking food, insist on violence.
Much as some people have found it convenient and reassuring to imagine that their blood is so special that it acquires a different colour, blood in any human body is bright red when freshly oxygenated and travelling via the arteries to deliver oxygen to the body’s tissues. But it is a darker red in the veins, when it is on its way back to the heart for another infusion of oxygen.
When I think of hemoglobin, I imagine millions of miniature versions of Sisyphus. As a punishment for deceitfulness, Sisyphus, a king in Greek mythology, is sentenced to the interminable task of hauling a boulder up a hill, only for it to roll down again so that he has to push it right back up. Unlike Sisyphus, hemoglobin isn’t always struggling against gravity. For hemoglobin, the struggle is the laps that it must run around the body — laps that accelerate as the body works harder. The endless task of hemoglobin is to bind itself to oxygen and haul the oxygen to tissues throughout the body.
It takes blood about a minute to circulate through the resting body. When you get to work — chopping logs, hauling laundry, chasing toddlers, or trying to win a dragon boat race — you oblige your blood to work harder. As your arms and legs speed up, your blood is like a stagehand, supplying props at a furious pace as the play unfolds.
The best endurance athletes — especially in the ultimate cardiovascular tests, such as running 42.2 kilometres or racing a bike for three weeks through both the Alps and the Pyrenees — are the ones who transfer oxygen most effectively from their red blood cells to cells in their muscles. After refuelling in the lungs and being pumped back out by the heart, hemoglobin, in its oxygen-rich state, is called oxyhemoglobin. But once it unloads the oxygen at its destination points, it becomes hemoglobin again and scrambles through the veins back toward the lungs for another hit of oxygen, only to recommence its endless trucking route. Pity the hemoglobin of an elite runner in the Boston Marathon, or of a cyclist in the Tour de France. All work and no glory. No wonder Lance Armstrong and a legion of other cyclists opted for blood doping, withdrawing and later re-transfusing their own blood to deliver oxygen more effectively to their overworked muscles.
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 blo
od 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.
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