Do all humans have the same number of veins and arteries? If so, how does the body know how many and where to make these veins and arteries?
In: Biology
I remembered! My sister told me babies have extra veins in their arms and legs. Again, not fact checked
My mom (NP) told me that older people are able to withstand heart attacks better than younger people because their bodies created more arteries or veins to pass though over time;
I kinda paraphrased this but someone correct me if I’m wrong haha
My sister told me recently that women, or was it men, have extra veins in their arms and legs. Sorry I gave you no info here, just some shit my sister said lol
There are some veins in the inner side of the elbow that sometimes differ. The medial cubital and medial antebrachial veins. I don’t remember the exact ways (there are 5 or 6 ways of which 2 are common), but I know in some cases there’s a vein missing or just very underdeveloped. I remember this because my one arm doesn’t have one of the veins but the other does. It always frustrates doctors when they try to put an IV in.
There is not a perfect match. In the extremities, there is usually a paired set of veins next to each artery, that when viewed in cross-section creates a triangular arrangement of three circles. This is evident when doing ultrasound exams. In the cerebral (brain) circulation, the paired vertebral and internal carotid arteries, which terminate in numerous small arteries (for the vertebrals/basilar artery) and finally at the circle of Willis (see the Wikipedia page on the circle of Willis – good diagram). However, the venous (veins) drainage of the brain does not parallel this at all ([https://en.wikipedia.org/wiki/Dural_venous_sinuses](https://en.wikipedia.org/wiki/Dural_venous_sinuses)).
In the trunk of the body, the aorta (artery) runs parallel to the inferior vena cava (vein), so there is a 1:1 match there, but there is also the azygous and hemiazygous venous system that is returning blood towards the heart, with no matching arteries. Then there are venous plexuses, which are tangled networks of veins. We have one in our spine (Batson’s plexus), and how do you count how many veins that consists of?
Overall, in terms of count, veins probably win.
Source: I’m an MD that teaches anatomy to med students.
I just want to say that apparently, no cells in our body is farther than 5 cells to a blood vessel. Another fact I liked is that blood vessels always follow a fractal pattern. Same for a lot of structure in every form of life. Instead of coding for every cells in the body ( DNA is not long enough to code for every cells in a body) there is instruction for a fractal pattern. The DNA code for the recipee, where to start and where to end. Other stuff in the DNA’s environment dictates when the recipe is made.
“The DNA is like a cake recipe. If you want to make a cake, here’s how. It doesn’t decide when it’s made.”
Quote from Robert Sapolsky, IIRC.
Wasn’t there a recent post that said babies are being born with an extra artery in their arms nowadays?
As others have said: generally large veins are consistent among people and small veins differ and the former is part of your DNA.
What I haven’t seen mentioned is two interesting things:
1. Sometimes there are surprisingly major changes that follow in family lines – normally we’d class these as genetic defects but sometimes they lead to totally functional people with weird quirks. There’s a lot of redundancy in the system so it can handle even major modifications.
2. Related to the above, things like major injuries, varicose veins or surgery can lead to your body restructuring your veins. My father, for example, had several major blood clots and had his entire Greater Vein of Saph removed, so several of his other leg veins have changed significantly to compensate for its loss.
How does the body know how and where to make arms and legs?
When humans are conceived the DNA we get from our mom and the DNA we get from our dad combine to make one big blueprint of the entire human body. It’s ~99% similar for all humans. It’s why we all have a brain, liver, kidneys, etc. All the major stuff is the same in each human because of the blueprints we share in our DNA.
I think you might be thinking of *capillaries*, though? Arteries and Veins are like the highway system for blood in the human body while capillaries (small blood vessels) are like the side streets. Capillaries help deliver blood to tissues away from the “highway”. The bigger a person is (both in terms of height and body fat) the more capillaries they need.
TL;DR: We’re born with the major veins and arteries we need, but the body builds capillaries and blood vessels on demand.
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