Geek Out: The Most Valuable Liquid On Earth?
Hair in funny places:
When we needed to have “those” conversations with our children, Babette Coles books were the most brilliant resource – take a look at them, the pictures, the text? They’re just perfect.
https://www.goodreads.com/author/show/110570.Babette_Cole
Glorious fruit cake:
I’m British, I use American spelling but dear reader allow me this one, fruit cake is delicious.
That circuit starts where?
Technically, because blood flows around a closed loop, we can’t actually say where it begins and ends its journey. The righthand side of the heart is a good place to begin our considerations because it’s pumping blood out for the crucial oxygenation part of the process.
Trillions:
You might be thinking I’ve used this word for dramatic effect but no, an average human body is thought to contain around 30 trillion cells (check out my blog post on the cell if you want to know more) and our erythrocytes make up a whopping 85% of our cells, hence trillions of erythrocytes too!
5 liters:
Pints is perhaps surprisingly, a rather problematic term! Imperial pints (as referred to in the UK) are 20% larger than US pints so where UK doctors talk about a typical adult having 8 pints of blood, that same doctor in the US would have to say 10 pints. Liters are liters are liters – the same everywhere and that’s why scientists like them!
Oxygen:
More words and we would look at the almost equally important job that blood carries out at the same time as it’s dropping off oxygen – it’s picking up truly ghastly stuff, carbon dioxide which will kill us if the levels get too high. When blood collects oxygen at the lungs it also drops off that carbon dioxide so we can get rid of it by just… breathing out!
Jam-packed:
This hemoglobin protein is so precious that as they’ve journeyed through evolution, erythrocytes have lost the nucleus that all cells have so that they can pack in more of these priceless protein passengers.
Erythrocytes:
From Greek, Erythro = red, Cyte = cell so erythro+ cyte = red cell
Bone marrow:
Hip bones, vertebrae, sternum, ribs and the cranial bones (those that make up the skull) are all sites of the red bone marrow that makes all the different cells that we have in blood. Donations of bone marrow used to typically come from the hip bones although there are now techniques that allow blood cell-creating stem cells to be extracted from a donor’s blood rather than from one of those skeletal sites.
Liver:
This is why when people have liver failure, they go yellow – the liver can’t keep up with the disposing of the breakdown products of erythrocytes which happen to be yellow and so they accumulate, coloring things like our skin, the whites of our eyes etc.
There’s some debate in the scientific community about how much of the initial breakdown is done by the liver and how much by the spleen. The spleen also gets involved although clearly, it’s not the whole story because people who have their spleen removed, still manage to have normal numbers of erythrocytes.
3 million new erythrocytes every SECOND:
Here’s how I got to that crazy number!
Every microliter of blood has around 5 million erythrocytes, and there are a million microliters in a liter – so in every liter of blood, there are around 5 million, million erythrocytes cells/L
But the typical adult has around 5L of blood so that means around 5 x 5 million million erythrocytes per person (or 25 million million cells).
If they have a typical life span of around 120 days then roughly speaking about 1% are destroyed every day and so that same number will need to be produced every day, to keep the numbers the same – so that’s around 25 with 10 zeroes after it.
There are 60 seconds, 60 mins and 24 hours in a day = 86400 seconds every day
25 and ten zeroes/86400 / 86400 = number of cells produced every second = 2893518 erythrocytes/second (almost 3 million every second!)
Erythropoeitin:
I do just want to mention the rather serendipitous discovery of EPO – prior to the widespread use of dialysis, everyone with kidney failure, well, died! Once these patients started surviving their kidney problems through dialysis, it was seen that they had profound anemia which answered the question, what was controlling the bone marrows production of erythrocytes – it was the kidneys. Dialysis could do the other jobs of the failing kidneys but it couldn’t do that – still, now we knew it was one of the jobs of the kidneys, to make EPO and it wasn’t that long before we learned all about EPO.
