Do humans have the same blood that we had as a kid? How come blood doesn’t expire inside of us since we range from different temperatures and are exposed to oxygen etc.

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Do we somehow maintain the same blood for the rest of our lives and we just pump more if we lose some. Blood expires in hospitals and not when inside of us?

In: Biology

5 Answers

Anonymous 0 Comments

Red blood cells have a lifespan of about 120 days, no more. When red blood cells mature, they lose their nucleus so that they can’t reproduce at all. That’s why they have to be made in special tissue inside your bone marrow. Not only that, but red blood cells lose pretty much *all* their organelles – they don’t have ribosomes or mitochondria.

Red blood cells are essentially sacks emptied of everything except for hemoglobin to carry oxygen and the bare essentials to keep the cell together to hold it all together. Although they are alive, they are barely alive and barely have a metabolism. They can’t sustain themselves, and don’t really need to.

Other cells in your blood, like some immune cells, are a lot more self-sufficient, but they get replaced often as well. The upshot of this is that your blood *does* expire inside of you, just not all at once. There’s a constant supply of fresh cells, and old cells are cleaned up in your spleen and liver, where they’re destroyed by macrophages (a type of immune cell).

Old blood cells can just fall apart and become food for bacteria. Those bacteria release toxic products. In your body, most blood cells are cleaned up before bacteria eat them, but when it does happen your body quickly cleans up the toxins with your liver before they can reach dangerous levels. In a bag in the hospital, there’s nothing to clean up old cells. They keep dying and falling apart, bacteria start eating them, and there’s nothing to clean up the bacteria or their toxic waste.

For the most part, your body doesn’t have the same *anything* that you did as a kid, with a few exceptions. Neurons in your brain stop reproducing by age 5 or so (probably), so although connections between them change and grow, and other cells in your brain like your glial cells (which support your neurons) continue to divide, you are born with most of the same individual neurons that you die with. Heart muscle cells reproduce slowly, but they do reproduce. And there’s some non-living stuff in your body, like your teeth, that don’t change appreciably. But other than the few exceptions, you body is constantly repairing tissue and organs by replacing cells.

Anonymous 0 Comments

Your blood, along with almost every other cell in your body, is being constantly renewed. With red blood cells it is the job of the liver to cull old red blood cells and this is the primary reason why your poo is brown – oxidised iron in old red blood cells being excreted.

The average lifespan of a red blood cell is 120 days. Most other cells in your body have an expiry date.

Anonymous 0 Comments

Your body is constantly destroying old red blood cells and making new ones, so any given red blood cell that’s currently in your blood stream isn’t that old. The blood plasma which the red blood cells are suspended in is basically water, so it doesn’t “expire.”

Anonymous 0 Comments

New blood cells are constantly broken down and replaced. They develop in your bone marrow. One of the breakdown products is called bilirubin and is what makes your poop brown.

Anonymous 0 Comments

>Blood expires in hospitals and not when inside of us?

Circulation, and constantly replenished air supply to combat effects of respiration. Live animals have blood circulation, dead carcasses blood get pooled and soon the meat is unconsumable or just bad tasting.

Blood storage is usual…refrigeration. plasma storage use agitators.

That’s all i know how to eli5. Further explanation may not fit eli5 as it will involve analogies and slaughtering vs knocking animals out on the head. Too complicated