Let’s say in the case of someone losing their arm at the shoulder; How does our body rebuild?
In: Biology
Your body doesn’t reroute flow per se. You will bleed out if a tourniquet is not applied with proper pressure.
For some people who experience shock, a symptom named vasovagal syncope will occur as a pseudo protection mechanism where you body will drastically decrease blood pressure. The pressure decreases because the arteries in your legs dilate and blood pools away from your upper extremities. This is why severing your femoral artery can lead to a quick death.
However, one method your body will technically reroute blood is through your diving reflex. This takes place while mammals and other air breathing vertebrates are submerged and the body focuses the blood to your heart and brain to prolong survival. However this physiological response is also noticed in the same animals near death.
Your body’s circulatory system and veins are like a city’s grid system of roadways. Traffic (your blood) is constantly following until road work (severed limb) causes a major roadway to be shut down for repairs and maintenance. Sometimes that means the construction workers (surgeon) has to change the flow of traffic (blood) by setting up detours in your body and redirecting where they want the road to go. They reconnect the veins that have been damaged, causing traffic (your blood) to flow properly, albeit redirected via different side streets.
When my college made our campus “closed”, they cut off certain roads and redirected others to flow traffic around the campus instead of through it. A surgeon does something similar when repairing a major artery to your limbs. The body follows these detours that were made to your body as if traffic cones were setup.
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You mean after the surgery to save you? A good suegeon will make sure he connects all nescessary bloodvessels for your body to function. Your vascular system is mostly parallel not seriell. So blood does not travel down the arm and then go somewhere else or such. The big atery that goes down in front of your spine splits up into smaller one as it goes down, giving all extremities their own supply
Imagine a long dead end street with houses along it. Now think about how the plumbing system to those houses works. There’s a water main that runs down the street to the end of it. Coming off this water main are pipes, each of which leads to a house. Inside the house, the pipes split up and go to sinks and showers and toilets. From those places, drain pipes run down and join to sewer pipes, and each house has a sewer piper leading back to a main sewer pipe under the road. Water flows through these pipes in the sequence I just described.
Now, what happens if you “amputate” the end of the street by digging it out into a big hole? You have to cap off the end of the mains and sewer pipes to stop water from spraying out everywhere, but other than that, you don’t have to do any rerouting. Why? Because each house has its own independent supply of water from the mains. The houses in the remaining part were not at any point getting water that had flowed through the houses in the part you dug away, so to them it doesn’t matter that the rest of the street isn’t there anymore. The mains and sewer pipe weren’t connected down at the far end of the street or anything, so you don’t have to join them together.
Blood vessels work the same way. Arteries lead into your arm, they split up into smaller and smaller blood vessels going to the different parts of your arm, which split into capillaries which fill all your tissues and provide blood to your cells, then blood flows from those capillaries and back into veins and then out. Arteries never connect directly to veins, and the blood going to the upper part of your arm doesn’t travel down to the bottom of it in the first place so there’s no need to really worry about rerouting. You just have to prevent blood loss from the ends of major veins and arteries until they heal up.
Short answer: in the case of losing multiple limbs your body reroutes nothing and in nature you will just bleed to death.
In clinical practice they tourniquet off limbs to reduce blood flow to that area and tie off arteries to stop you from exsanguinating.
In terms of compensating in shock your body tightens your peripheral blood vessels (I.e. your other limbs) to improve your blood pressure and reduces how much you wee to reduce loss. It also increases how hard your hard pumps to improve the amount of blood your heart is pumps each minute.
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