Monday, 5 April 2010

Blood is three times thicker than water...

Background: there is an expression that says "blood is thicker than water" - I wondered if it was true in a literal sense.
Main Source:
Topic: Biology/Sayings

Details: It's pretty obvious that blood is indeed thicker than water...but by how much? One thing to look at is the density of blood. This can be done by taking a sample, of known volume, and weighing it. I don't have any I can spare so I looked it up.

"Blood is a liquid tissue composed of roughly 55% fluid plasma and 45% cells. The three main types of cells in blood are red blood cells, white blood cells and platelets. 92% of blood plasma is composed of water and the other 8% is composed of proteins, metabolites and ions. The density of blood plasma is approximately 1025 kg/m3 and the density of blood cells circulating in the blood is approximately 1125 kg/m3. Blood plasma and its contents is known as whole blood. The average density of whole blood for a human is about 1060 kg per cubic meter."

So a density of 1.06 g/cubic centimeter, compared with water's 1 g/cubic centimeter, means it's only a little denser.

But to get an idea of it's thickness, I think we should also look at its runny/sticky it is.

According to Nicole Davis, a grad student (Department of Genetics, Harvard Medical School) it is about 3 times greater than that of water:

So blood really is thicker than water, about 3 times in fact.

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