Transcription
Hi everybody. Today we'll start a new series about red blood cells, white blood cells, hematology, oncology; everything you need to know. Because hematology is one of my favorite subjects. These videos will be short; you have to watch them in order to get the idea. Okay, let's get started.
In a previous video, we have talked about the hematopoiesis, multipotent stem cells, myeloid and lymphoid. The myeloid will give birth to: erythroid progenitor, erythroblast, or rubriblast, reticulocyte, erythrocytes, which are the RBC's. So please go and watch the video of hematopoiesis first.
Welcome back. Do you see this pathway from myeloid stem cells down to the RBC's? Two things happen as we go from here to here: Number one, the cells become smaller. Number two, the cells lose their nucleus. So this cell is like this and has a nucleus; the RBC will be like this with no nucleus. Also, all of this is influenced by a hormone produced by the kidney called erythropoietin, short as EPO, Pipo, or Hero.
So we said that EPO is produced in the kidney, but let's be more specific. We're in the kidney cortex or medulla? Cortex. We're in the cortex, the interstitial cells of the peritubular capillary bed. Interstitial cells, peritubular capillary bed in the cortex. That's the normal. However, in certain cancers, they can produce EPO. We call this process paraneoplastic syndrome, such as renal cell carcinoma and hepatocellular carcinoma. They can produce EPO as well.
So what does EPO do? It increases the number of blood cells, the red blood cells, by stimulating the bone marrow. Stimulating the factory: "Hey, bone marrow, I need more RBC's, please." That's EPO's job. Okay. So first you have to know that there is an inverse relation between oxygen and EPO. When oxygen goes down, EPO goes up. When oxygen goes up, EPO goes down. So that's number one. Number two: Oxygen content equals the percent saturation of oxygen plus the PaO2 (free oxygen in the blood). So both of them are called oxygen content. Hypoxemia is a decrease in the free oxygen in the blood. Decreased O2 sat is a decrease of the saturation, which is oxygen on the RBC's, oxygen bound to the hemoglobin on the RBC's. Okay, so hypoxemia and decreased O2 sat decrease oxygen content and increase the EPO.
While polycythemia vera, we have more RBC's; we have more oxygen on those RBC's, so the EPO will go down. What about high altitudes? On high altitudes, the air is thin; the oxygen is less, so we have to get more RBC's to try to carry as much oxygen as possible. That's why we will produce more EPO. Left shift of the oxygen dissociation curve. In physiology, when we left shift the curve, that means that we are not giving oxygen to the tissue. Okay, so I need to get more EPO to get more RBC's to carry as much oxygen as possible. So polycythemia vera will have low levels of EPO. Hypoxemia, low O2 sat, high altitude, left shift of oxygen dissociation curve will have high EPO. EPO increases the RBC's to carry more oxygen, so we get more energy. That's why some athletes take an artificial form of EPO called Epoetin to increase energy. Okay. That's why this man is happy after taking the artificial EPO. It's made by DNA recombinant technique.
That's it for today. In the next video, we will discuss reticulocytes and what's a reticulocyte; what's that? All you need to know in the next video in our series for hematology/oncology. Stay tuned, subscribe to get new videos, and thank you very much for your support.