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– Credit: Catherine The station
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A broken heart, learn by rote, from the bottom of the heart … These idioms and many others date back to the early Bronze Age and ancient Greece, when philosophers believed that the heart was responsible for intelligence human, movement, memory and emotions.
Now that we have a better understanding of human anatomy, we know that it is the brain that is “at the heart” of these human abilities, and that the venous organ that beats in our chest is actually a pump that powers the rest of our body in oxygenated blood.
Christopher Ramnanan, associate professor in the Department of Medical Education Innovation in the Faculty of Medicine, shares five interesting facts about the heart that people may not know.
1. Two hearts are better than one
The human heart has four chambers: the left and right atria, which collect blood from the body and organs, and the left and right ventricles, which pump blood out of the heart.
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“What is less well known is that these cavities are organized to function essentially as two separate hearts, involved in two different blood circulation systems. So,
from a functional point of view, we actually have two hearts in our chest, which pump at different pressures and each with their own purposes, ”explains Professor Ramnanan.
The right heart collects blood from all tissues in the body in the right atrium. This blood is then sent to the right ventricle, which pumps it to the lungs for oxygen. The right ventricle pumps at a moderately low pressure, so as not to damage the delicate tissues of the lungs. “He’s a conscientious neighbor,” says the professor.
The left heart collects oxygenated blood from the lungs. From the left atrium, blood travels down to the left ventricle and then is pumped to the rest of the body through the aorta, the largest artery in the body. The left ventricle pumps blood at a higher pressure because it has to work against gravity to push the blood up to the head, while also pushing it down to the feet. The left ventricle is therefore thicker and more muscular than the right, because it works harder.
2. The heart is in the center
“During the national anthem, when people put their hands on their hearts, they tend to place it way too far to the left,” explains Professor Ramnanan. “It is true that the heart is oriented a little to the left, but most of the tissue is located right in the middle of the chest, comfortably placed behind the bony protection of the sternum, or plastron. Not bad in terms of design, right? “
Indeed, the heart lives in the mediastinum, a central cavity of our chest which literally means “what is in the middle” in Latin. It was this very conception that led thinkers like Aristotle to determine that the heart was the most important organ in the body and the seat of vitality. Aristotle believed that the brain and lungs existed only to cool the heart.
It was not until 1628, when the English physician William Harvey wrote that the primary function of the heart was “the transmission of blood and its propulsion”, that beliefs began to change. The French philosopher René Descartes was one of the first to describe the heart as a mechanical pump, in his book Discours de la method published in 1637.
3. The heart begins in the shape of a tube
In utero, a baby’s heart develops in the shape of two tubes, like finger catches. After four to eight weeks of growth, the tubes merge and undergo extensive transformations.
“Initially, we have only one atrium located under a ventricle, with a single circuit of blood circulation,” he explains. “This single-circuit heart then experiences significant growth, looping and folding. Finally, the atrium and the ventricle are divided into two, giving us a total of four compartments. As the ventricles grow larger, they begin to descend below the atria, giving the organ its final shape ”.
4. The most serious problem of arterial obstruction is nicknamed “widowmaker”
Coronary arteries are the blood vessels that connect the aorta to the heart. These arteries take up some of the oxygenated blood to feed the heart itself – because it also needs oxygen to function.
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“There is a right and a left coronary artery, each with several branches supplying specific parts of the heart,” says Professor Ramnanan. “When there is a blockage in one of these branches, it prevents part of the heart from being supplied with oxygen. This lack of oxygen leads to damage and the associated pain that we feel in the chest and shoulder. This is a heart attack. It’s the lack of blood flow, or the blockage, that is the problem. ”
According to Professor Ramnanan, the left coronary artery and one of its branches, the left anterior descending artery in particular, are more likely to become blocked than any other artery. The obstruction problem in this critical area is so common and dangerous that it is called in the jargon “widowmaker”.
The moniker probably stems from an old misconception that heart disease was mostly a men’s problem. “When I was young, I remember thinking that heart attacks happen to fathers more than mothers,” he says. “I think it’s widely accepted now that heart disease and other heart problems affect everyone. In fact, recent studies have shown that statistically it’s actually more common in women. Significant research is currently being conducted to understand why. ”
5. Heart attack ≠ cardiac arrest
“I’ve heard the terms ‘heart attack’ and ‘cardiac arrest’ used interchangeably, but they’re actually two different things. ”
A heart attack is a blockage of the arteries that interrupts the flow of oxygenated blood to part of the heart. Cardiac arrest means the heart stops beating, but not because of problems with the blood circulation. “It’s more of an electrical problem,” explains Professor Ramnanan.
“The heart has its own electrical wiring, and for some reason it can stop working. Most of the time, it’s sudden and brutal, and it feels like being out of breath. If you have time to feel something before you lose consciousness, which is not always the case, you may experience weakness, fatigue, dizziness, and shortness of breath because the pump has stopped working all the time. suddenly and there is no more blood flowing to your brain, organs and limbs. “
Professor Ramnanan explains that as humans we are very good at detecting the lining of our body and our external tissues. If someone touches the back of our right knee, for example, we will be able to pinpoint the location of that contact.
“But we are very imprecise about the sensations in our organs. In a heart attack, the pain is generally interpreted by our spinal cord to come from our arm and chest wall, rather than our heart. We generally call this radiated pain. Maybe it’s a matter of evolution, because we don’t want to be bothered by every little thing that goes on inside. But it also makes it harder to spot a problem and accurately describe it to a doctor. Fortunately, healthcare professionals are well trained to relate the common patterns of radiated pain in patients to the probable underlying causes. ”
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– The teacher Christopher Ramnanan with his daughters, “his two hearts ».
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The heart remains a subject of great interest. It is one of the organs that fascinates the general public the most. After all, there are no parties with kidney-shaped candies or liver-shaped chocolates (probably for the better).
This is why the heart is generally at the center of the promotional activities offered by the Division of Clinical and Functional Anatomy of the Faculty of Medicine. These outreach activities aim to educate the general public about human anatomy, using educational resources like their organs in body donation program. These events are a great opportunity for medical students to gain some teaching experience by interacting with members of their community.
The Division of Clinical and Functional Anatomy and medical students at the University of Ottawa are eager to resume offering these events to the public once the pandemic has passed. The heart, of course, will remain at the center of it all.
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