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Essentially what I'm asking is that if someone's arm is amputated, doesn't that cut off a significant part of their blood flow because the blood vessels that normally flowed up to the hand of the amputated arm and back can't anymore? If it heals, does that mean the body has to grow more vessels to sort of complete the circuit again? Does the body just compensate by putting more stress on the rest of the body's blood vessels?

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    $\begingroup$ Is it in reference to surgical amputation? $\endgroup$ – Imtiaz Raqib Dec 15 '16 at 6:43
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    $\begingroup$ please mention the source from where you found the information that cut at one place affect circulation at rest-portion of the body. However not much answer but from very common sense it seems logical. If you have a pipeline for water at your home and the pipe leaks, the water pressure would fall, so you would get slower water. Also in case of that healing; certainly some new blood capillaries regenerate but when the hand is no more, I think there is no need to regenerate the long arteries and veins for hands. just 'sealing' wounds and make a close-circuit with capillaries seemingly enough $\endgroup$ – Always Confused Dec 15 '16 at 9:35
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If I understand your question correctly, you ask how does the body deals with released blood volume after the removal of part of blood vessels?

The simple answer is the body decreases the blood volume. Our body is able to alter blood volume significantly in response to different factors.

For example, take a look at this paper: Blood volume changes in normal pregnancy. It states that:

A healthy woman bearing a normal sized fetus, with an average birth weight of about 3.3 kg, will increase her plasma volume by an average of about 1250 ml, a little under 50% of the average non-pregnant volume for white European women of about 2600 ml.

So, after the arm cutting, an organism will decrease its blood volume. Although it will take some time, blood volume altering is more probable way than new vessels generation.

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Amputation of a limb or more will cut off both the arteries and veins to and from that limb. The body will compensate by reducing the amount of the circulating blood in it in order to maintain normal blood pressure. The best analogy I can provide would be electrical circuits: In amputation you are removing a circuit that is connected as a parallel circuit, not as a series circuit, therefor there is no need to create new connection after amputation to allow the circuit to complete, you just need to block the loose ends (ligate the main artery and vein to the amputated limb).

Amputation does not lead to increased stress on the remaining part of the system, in fact it has the exact opposite effect. The heart as a pump becomes more efficient as the "piping system" is now shorter with less resistance, and people with cardiac failure report feeling improved cardiac symptoms after amputation, and those with high blood pressure require less medication to control their blood pressure. In fact, the functional efficiency of all other vital organs like the kidneys, pancreas and liver improve as a result of reduced body mass (they now need to service and detox less cells). If the person was diabetic, their requirements for external insulin reduce, and people who suffer kidney failure might no longer require dialysis as the remaining kidney function -although compromised- becomes sufficient to filter the smaller amount of blood which includes less -waste chemicals- due to reduced muscle and fat mass.

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    $\begingroup$ I'd like to see references for the core statements (blood amount is reduced in response to limb loss, and improved heart function after limb loss), but the main point is correct: our circulatory system consists of thousands of smaller parallel circuits that branch off the main vessels in the trunk. As soon as blood clotting has taken care of the actual leakage, the rest of the system goes back to stable. $\endgroup$ – Armatus Nov 10 '18 at 19:04
  • $\begingroup$ There are limited references in peer reviewed journals in relation to this subject. Studies related to amputees are very limited due to this area of science being too specific as amputees represent a relatively a small percentage of the population. However, total blood volume is generally calculated based on the person's weight as the main predictor, and limb amputation clearly reduces weight leading to reduced circulating blood volume: reference.medscape.com/calculator/estimated-blood-volume medicalalgorithms.com/blood-volume-after-amputation $\endgroup$ – Matt Dee Nov 16 '18 at 7:50
  • $\begingroup$ Fair point about blood volume. I was still wondering about the improved heart function though, and I haven't been able to find evidence for that. To the contrary, when looking at the risk of heart attacks, it seems patients who lost a limb due to peripheral vascular disease have an even increased risk, and patients with limb amputation for other reasons have no change in risk (jneuroengrehab.biomedcentral.com/articles/10.1186/…). For leg amputees, cardiovascular complications seem to be increased generally (academic.oup.com/qjmed/article/101/4/251/1544580). $\endgroup$ – Armatus Nov 17 '18 at 16:16
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    $\begingroup$ Cardiac function improvement refers to the immediate improved efficiency of the heat as a pump following amputation, due to the reduction in the vascular tree this pump needs to service, while the cardiac muscle remains unchanged, and still at a high risk of further clots leading to future deterioration of cardiac function. Unfortunately I couldn't find references to support this statement, but if you ever meet a vascular amputee I expect you will be able to confirm that it is true. $\endgroup$ – Matt Dee Nov 18 '18 at 6:51
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    $\begingroup$ You are absolutely right about the increased risk of cardiovascular complications following vascular amputations, but this is different from "improved cardiac function following amputation".Vascular amputees had narrowing in the main artery leading to the limb, and this is usually part of the systematic vascular problem. These people will continue to be at high risk of vascular complications in other organs following a vascular amputation, and statistically speaking, a vascular amputation is considered a predictive risk factor for further vascular problems in other organs. $\endgroup$ – Matt Dee Nov 18 '18 at 6:54

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