Transcription
In this lecture part, we will separately talk about eskeemia. The word eskemia comes from two Greek roots. Isco meaning restriction or suppression and emia referring to blood. So essentially eskemia is a reduction or blockage of blood flow in an organ or tissue, which leads to impaired oxygen supply.
As we know, blood is the main carrier of oxygen in the body. If blood flow to cells decreases, the supply of oxygen is also reduced. This can happen in two main ways. One is internal obstruction. For example, a trombus or blood clot, which forms from platelets and proteins for various reasons and blocks the vessel from the inside. Normally, clots form when needed, of course, such as when there's a wound, but for different reasons, they can also form in otherwise healthy blood vessels. In that case, the trombus blocks, of course, blood flow.
The second possible cause is external compression. For example, after tissue injury, inflammation can develop, leading to swelling, which then physically compresses the blood vessel from the outside. Usually, such swelling is temporary and resolves quickly. But if it persists and continues to block the vessel, it can also lead to eskeeia.
As we already know, arteries are like one-way highways carrying the arites to organs. Here we have an organ made up of many, many cells. In the capillaries, oxygen is delivered to the cells. In this case, my purple organ here. And metabolic waste products are collected. This includes carbon dioxide, of course, which is produced during this citric acid or crep cycle. If, for example, there's an obstruction in the artery, such as a thrombus or something else, blood flow decreases, and as a result, the organ receives less oxygen. And this means this purple organ here has a risk of becoming eskeemic.
Unfortunately, one of the most typical and common examples is es is eskeemic heart disease, where the heart tissue itself suffers from lack of oxygen. To avoid any confusion about this picture here, I'll clarify that in this diagram, the artery shown here represents the coronary artery. Otherwise, it might seem confusing because arteries don't go to the heart, as you know, in the usual sense. But here we are specifically talking about the coronary arteries, which branch from the aorta and supply the heart muscle. So, for the heart to function properly, it also needs oxygen, of course, since, as we know, the heart works continuously and intensively. This oxygen is delivered so by the coronary arteries.
In such a situation, as I mentioned, we got an eskeemic heart disease here, also called myocardial eskeemia. One of the most common causes of it is atherosclerosis, which is a chronic disease of the blood vessels. It develops when fat-like substances, most often cholesterol, accumulate on the walls of the coronary arteries, gradually narrowing or blocking blood flow. And as a result, the heart muscle does not receive enough blood, thus not enough oxygen, and therefore cannot function properly.
The consequences of eskeeia can be quite serious. If the oxygen supply is sufficiently low and lasts long enough, the cells begin to die. Here you can see many dead cells. When a large number of cells die, we call this necrosis. As you know, necrosis is, I remind you, a natural cell death. When not just individual cells but whole areas of tissue die, we call this an infarction. The most commonly known example is again mocardial infarction. But infarction can occur in other tissues as well. By definition, it is tissue death in any organ or part of an organ caused by interruption of blood supply.
But if, before the cells die, the blockage is removed, then the cells can still be saved. Although they may still have a higher risk of infuction if the blockage happens again in this place, at that moment, they are still viable. However, if the cells have already died, then nothing more can be done. Cells that have undergone necrosis are permanently dead.
In some tissues of the body, there are two or more arteries supplying the same area. These are called collateral arteries, and they can provide sufficient blood flow if one artery becomes blocked. Over time, these vessels can even then enlarge to compensate for the blocked main artery. Well, of course, as I mentioned, time is critically important. How long the vessel remains blocked. The faster blood flow is restored, the better the outcome. If circulation is restored in time, the affected cells, although temporarily impaired, can recover and gradually return to normal function.
And as I mentioned before, one of the most well-known irreversible consequences of eskeeia is unfortunately myocardial infarction, commonly known as the heart attack. This occurs when one of the coronary arteries, which supply the heart muscle with blood, becomes blocked. Most often, as I mentioned earlier, this happens due to attherosclerosis or trombosis. When a trombus blocks the coronary artery, as a result, part of the heart muscle does not receive oxygen, and the cells that are in that area begin to die.
Depending on the location and extent of the damage, this can lead to serious disturbances in the heart function and, unfortunately, even a fatal outcome. For example, if a large portion of the left ventricle is affected, which is the most important part of the heart responsible for the systemic circulation, then the heart may lose its ability to pump blood effectively. And this can lead to heart failure and life-threatening conditions, and in severe cases, of course, death.
This is why it is extremely important to recognize the symptoms of a heart attack and call emergency medical services immediately. But even more importantly, it is best to prevent reaching this stage by maintaining cardiovascular health and avoiding the development of severe arterial blockage in the first place.