Here are 10 remarkable facts about blood from the “Incredible Machine.”¹

1. Human blood retains a link to ancient Cambrian seas: The same balance of salts and minerals that existed in primitive oceans half a billion years ago is present in blood.
2. Blood is a liquid tissue: Fluid makes up more than half while plasma, white, and red blood cells make up the remainder.
3. The heart expels 2 ounces of blood with each beat, 5 quarts of blood each minute and 8,610 quarts per day.
4. Red blood cells (erythrocytes) are the body’s cellular lungs. Their job is to ferry oxygen to every cell and remove carbon dioxide.
5. If the red blood cells from one person were to be stacked, they would reach 31,000 miles high.
6. Each red blood cell has 270 million hemoglobin molecules. Each hemoglobin molecule can carry four oxygen molecules.
7. The hemoglobin in red blood cells scoops up oxygen molecules in oxygen-rich tissues, such as the lungs, and the releases them in oxygen-deprived tissues throughout the body.
8. Each second, we lose about 3 million red blood cells only to be replaced by the same number produced in the bone marrow.
9. Venous blood that delivers carbon dioxide back to the lungs makes up 75% of blood volume at any given moment.
10. Blood flow measurement is vital because it provides a window into the delivery of oxygen and nutrients to body organs and cells. To measure is to know!

Source:

¹The Incredible Machine 1992 National Geographic Society, Washington, DC