Liberal Arts Blog — Our Electric, Liquid Bodies (Part II): The Orion of the Blood
Liberal Arts Blog — Wednesday is the Joy of Science, Engineering, and Technology Day
Today’s Topic — Our Electric, Liquid Bodies (Part II): The Orion of the Blood
Orion is my master key. My favorite teaching tool. A constellation defined by seven stars in a very precise configuration — a central belt of three plus four peripheral stars. The pedagogical challenge of any subject is to tell as complete a story as possible in the order that makes the most sense. So what is the story of the blood? The three stars of the belt are the three basic functions — transportation (eg. oxygen, nutrient supply and carbon dioxide and waste removal), defense (hormones, antibodies, clotting), and homeostasis (PH, temperature). The four peripheral stars are the four components of blood (plasma, red blood cells, white blood cells, and platelets). Experts — please chime in. Correct, elaborate, elucidate.
84% OF ALL OUR CELLS ARE BLOOD CELLS!!!!!
1. What? Seriously? How many is that? About 35 trillion!!!!!
2. That makes no sense, right? Only 7% of our weight but 84% of our cells? Hmmm. Is science, like religion, all about faith?
3. 40–50% of blood cells are erythrocytes (red blood cells). The body produces about 2.4 million of these per second!!!!!! No way! Do you really believe that?
NB: But that’s cheating, right? Red blood cells aren’t really cells. I mean they lose their nucleus early on and have a life span of only 120 days. Quibble, quibble. Oh by the way, blood is 80% water and 20% solid. And the average man has about 10 to 12 pints of it and the average woman 8 to 9 pints. And remember that each of those red blood cells has about 300 million hemoglobin molecules for oxygen delivery! Have you thanked your erythrocytes recently?
BY VOLUME 55% OF BLOOD IS PLASMA — THE LIQUID COMPONENT
1. So what is plasma? 92% water by volume.
2. What else? Proteins, glucose, mineral ions, hormones.
3. Principal protein: albumen. Who needs albumen? For what? “the oncotic pressure needed for proper distribution of body fluids between blood vessels and body tissues; without albumin, the high pressure in the blood vessels would force more fluids out into the tissues.”
WOW! LOOK HOW FAR BLOOD TRAVELS! AROUND THE WORLD TWICE!
1. Only a tiny fraction of the circulatory system is visible to the human eye!
2. That would be at most one mile of the 50,000 miles of capillaries in the human body!
3. 10 pints of blood spread out over 50,000 miles! Sure. Yeah, right. Whatever you say.
A LINK TO THE LAST THREE YEARS OF POSTS ORGANIZED BY THEME:
Please share the coolest thing you learned this week related to science, engineering, or technology. Or, even better, the coolest or most important thing you learned in your life related to science and engineering.
This is your chance to make someone else’s day. Or to cement in your mind something that you might otherwise forget. Or to think more deeply about something dear to your heart. Continuity is key to depth of thought.