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My study materials use the word vesselcompression chamber of aorta to emphasize aorta's elastic property.

The arch of the aorta only coils, not its straight part. I think the reason why the arch coils is the elasticity of aorta (artery) is high. If the elasticity is too low, then the aorta is more stiff. This means that heart has to work harder so higher systolic pressure and lower diastolic pressure.

Why does the arch of the aorta coils?

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It's not clear to me what you mean by "coils". The aorta itself does not coil. Except for the arch, it's rather straight. Are you asking about the orientation of collagen and elastic fibers in the wall of the aorta? –  kmm Feb 8 at 13:44
    
@kmm This was the question which I got. It probably refers to the fact that it coils very little, exactly in the arch. Yes, I think the coiling of aorta can refer to the orientatino of collagen and elastic fibers in the wall of the aorta. –  Masi Feb 8 at 15:21
    
So if that is the case, then can you rephrase or narrow down your question? –  kmm Feb 8 at 16:51
    
@kmm I narrowed to question to the arch. –  Masi Feb 9 at 7:34
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@Masi - I'm still confused by "coils." The aorta, as you said, is an elastic artery, and has many layers of smooth muscle and elastic fibers in the tunica media. Don't you mean: "if elasticity is low, then the aorta is stiff"? It requires high elasticity to help maintain a higher diastolic pressure. –  jello Feb 11 at 12:46

1 Answer 1

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The main question can be answered in a very dumb way: because the lower part of the body also needs blood... and this configuration is the surest way of doing that because of reasons given below (among many others, I am sure).

  • If you want an anatomical reason, well the most pertinent one would be that embryologically, the heart and vascular system are derived from a single straight tube, that then begins contracting and folding over itself to form the heart chambers, the aorta, and the pulmonary trunk.

  • If you want a physiological explanation, the aorta curves slowly because it is a point of the circulatory system where pressure is high. Apart from the fact that sharp kinks would cause a massive and useless loss of kinetic energy on blood flow from shear stress over the aortic walls (and therefore more heart workload), the induced shear stress would also damage the aortic walls much more quickly than in the actual configuration.

The third reason is just theory on my part, but it seems the vascular system is designed by priorities: you could imagine a system with two aortas. One for the upper body going up, and a second going down. However, such a configuration makes it mechanically impossible to balance perfusion to the organs, and especially ensure brain perfusion. For example, how would the body compensate if the upper aorta got clogged while the other stayed wide open? The single aorta configuration allows the heart to adapt to such mechanical perturbation scenarii using, for example, left ventricular hypertrophy.

However to add to some elements of your question:

  • the reason of the aortic coiling has certainly very little to do with elasticity and the vessel compression chamber principle.
  • Higher elasticity means the aorta is less stiff, not more.
  • When the aorta gets stiff (elasticity decreases) as it is often the case with age and calcification of the aortic walls, it is correct that the heart will need to work more, that systolic pressure will get higher, and diastolic pressure lower. This gives the classical clinical symptom of "cannonball" or "gunshot" pulse
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Excellent answer! Thank you! Can you provide me more information about the gunshot pulse. It reminds me about one case where the insulin secretion is like cannonball, here described: biology.stackexchange.com/q/17466/86 –  Masi Aug 19 at 5:59
    
The other way of rejecting the two-aortic system away is the impossibility of having atrophy in the heart, I think. The cell size of the heart cannot decrease. I have listed some factors here what it would require biology.stackexchange.com/a/16928/86 –  Masi Aug 19 at 6:05

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