Blood, in our day and age, plays nothing more than a supporting role to teen vampires on the big screens with perfect bed hair. Well today the fake fangs are coming off, the microscopes are coming out, and we’re giving blood the red carpet treatment it deserves in this segment of Forgotten Physiology.
Alright, take a deep breath and let it out slowly. We’ll need to shake off all those icky vibes we get whenever we mention the word “blood.” It’s time to take a closer look at that crazy vampire juice, and by closer I mean at roughly 400x magnification. I’ll wait till you catch up. Just say when. Outstanding, let’s get to it!
Oh sure, I realize that anyone who’s learned to turn on a computer or operate a stove when their parents aren’t home has probably figured out by now that our blood is composed of red blood cells. There are a few white blood cells floating around in the mix as well, fighting off infections but that’s for another article. Today I want to focus on the true work horses of our circulatory system, the red blood cells.
What is blood exactly? No wait, that’s a boring, safe question. Perhaps a better question might be why do we have blood? I mean what’s the evolutionary advantage of having a bunch of flat, pink disks floating around in a murky straw colored, neutral pH solution at 37 degrees Celsius? It’s all about clever chemistry my friends, gas exchange to be more precise. Red blood cells, or erythrocytes, as the cool kids (scientists) call them are nothing more than transport vessels. They are not unlike tiny FedEx drivers transporting their oxygen payloads from the lungs to the cellular tissues of the body (I never liked the term tissue…just feels dirty) “How do they accomplish this?” you cunningly ask. Ha! Well played.
Inside each red cell are specialized proteins called hemoglobin and inside these are tiny iron molecules. Like all proteins they are composed of certain amino acid chains that only fold a certain way, but what makes them unique and a hit at all the parties are their ability to cling on to that sweet, sweet iron. It’s not just any ole iron, but the ionic “taster’s choice” ferrous form of iron, Fe2+. These iron molecules have a real knack for accepting molecular oxygen, or O2. If you’ll recall, metallic iron tends to rust or “oxidize” when exposed to moisture and air. Once you’ve made that connection feel free to go “Ahhhh!”
There is however, another gas that our red cells love playing catch with and that’s carbon dioxide, CO2. You know that ole cellular metabolism that our cells go through to convert carbohydrates into energy is messy business. If it weren’t for our red cells that CO2 (the byproduct of respiration) would build up in our tissues slowly poisoning us, which is not ideal. The very same red cells transport that stuff from our tissues to the lungs for gas exchange, or as it’s known on the mean streets, “exhaling.” The other advantage red cells have for shipping gas to and fro is the fact that each mature red cell loses it’s nucleus. This makes room for gas exchange to take place, but it also limits the lifespan of the red cell. A mature (non-nucleated) red lives about 120 days. By that time it will have lost it’s ability to metabolize, let its facebook page expire, let himself go. Whatever, it’s just too old and worn down to be effective.
That is the basic mambo of our red cells. 24 hours a day, 365 days a year they carryoxygen to cells and carbon dioxide away from the cells. It’s pretty basic, reliable stuff. Blood is also quite honest. Those red cells travel through the vessels surrounded in fluid, which is mostly water and dissolved minerals, nutrients, proteins and gases. This funky fluid, or plasma interacts with everything, all the tissues of the body. So when you come down with an infection or any ailment for that matter, physicians, nurses, and lab specialists like myself rely on the blood to give us all the juicy gossip about what’s going down.
“psst…hey Dr. Oz, Mrs. Doe has high blood sugar today.” – Your BFF, the plasma
Now what is important to note about those red cells when it comes to testing the plasma is that they are alive. That’s right, they are still maintaining low levels of metabolism, a form of glycolysis the cool kids refer to as the Embden Meyerhof pathway (which sounds like a race track in Germany). Since these cells are alive and intact they are continually taking electrolytes in, but if those cells are ruptured they will release things like potassium and glucose back into the plasma. This can give the person examining your blood misleading and often alarming results. So if you’ve ever had your blood drawn one day and then got called back to the doctors office later to have the same tests redrawn due to “questionable results” there is a good chance that the blood was hemolyzed, i.e. those cells were ruptured in the process. Sorry about that, but it happens sometimes. Drawing blood is not an exact science and each individual’s vasculature is different. This can also happen when well meaning, handsome, young lab techs leave the tourniquet on for too long. Sorry Ms. Jackson [not her real name] I’ll lay off the cafe mochas next time.
So the next time you’re enjoying Twilight recaps on Hulu, getting your finger pricked at the doctor’s office, or knocking back a cold one while watching your favorite scene from Buffy the Vampire slayer (no question, an American classic) take a moment to appreciate the rosy, red concoction that makes it all possible. Red Blood Cells, this bud’s for you.
Stay classy my friends and never stop learning 😉