If you’ve lost blood, either by a severe cut or donating to a blood bank, your body can generate new blood to replace it. How does your body know when it needs more, and how does it know when to stop so you don’t end up with an excess amount?
In: Biology
Your blood is continually being made. Blood cells live for a couple weeks, then die and are reabsorbed by your body.
Donating blood also has a number of health benefits as well though I believe its due to the reduction of iron from your system and giving your kidneys regular exercise I think.
When you lose blood u can carry less oxygen you sense this in ur kidneys. The kidneys produce a hormone erythropoietin makes ur bone marrow make more blood when ur carrying capacity of oxygen is back to normal the hormone is set back to its normal lower level.
Thanks for all the comments!! I think I understand my adopted mom’s medical issues a bit better with this input. Thanks!
I’ll add that there’s a part of your brain that can detect when the volume of blood is too low. When this happens, the pituitary secretes ADH that causes the kidneys to conserve more water instead of excreting it in urine. This helps maintain the volume of blood and blood pressure in addition to the actual amount of red blood cells which has been explained by others here (erythropoietin).
Just another piece of info…
Also I’ve read a couple papers that say people who regularly donate blood seem to also have better outcomes when they suffer blood loss for other reasons.
That’s one of the reasons I continue two donate despite the fact that I have very difficult veins.
This is fascinating, can anyone speak to any disorders where your body can make too much blood?
I have a semi-rare disorder where my body makes too much spinal fluid! Lucky me it can be treated and it went smoothly. Funny thing about this condition (IIH/ pseudo-tumor cerebri) no one knows what causes it! Only how to fix it.
There is a hormone produced by the kidney called erythropoietin. That hormone makes the blood marrow produce more red blood cells.
When there isn’t enough oxygen reaching the kidney (because of the lost blood), it produces this hormone so more blood is made.
TL;DR: the kidney tells the blood marrow to make more blood
Your body has methods of measuring the actual amount of liquid blood in the vessels, as well as how much oxygen your organs are getting. This is done through a combination of chemoreceptors and pressure receptors. If your body senses it’s low on RBCs, it can release a chemical called Erythropoietin, which causes your bone marrow to up the production of red blood cells, and then it stops releasing that chemical once it detects the amounts are back to normal
Blood cells don’t live that long. The body has to make more of them all the time.
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