3 ms·

I hate to spread a wacky idea, but I ran across something on Facebook the other day that I initially wanted to disprove but then started to seem plausible. The

I hate to spread a wacky idea, but I ran across something on Facebook the other day that I initially wanted to disprove but then started to seem plausible. The general consensus is that the heart is a pump and generally the sole driver of circulation in mammals. There is an alternative theory, which seems easy to disprove, that the heart is more of a regulator and operates more like a hydraulic ram. I can post more links later. Curious if anyone has heard of that and if there is a rebuttal to the idea. Edit: The paper I was thinking of, if anyone is interested, is here https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5215277/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5215277/ Edit #2, from the paper: "Gladwin et al. estimated that 25% to 30% of basal human blood flow can be attributed to red blood cell-induced production of nitric oxide by vascular endothelium."

thaumasiotes 7y ago
> The general consensus is that the heart is a pump and generally the sole driver of circulation in mammals. It's certainly not the general consensus that the heart is the sole driver of circulation in mammals. Your heart drives the flow of blood out through your arteries; it's much less effective at driving blood back through your veins.
- TheSpiceIsLife 7y ago
  Veins contain one-way valves, so veinous return is aided by movement and muscle contraction. The lymphatic system doesn’t have a pump at all and is entirely driven by movement + muscle contraction + fluid pressure as a result of tissue integrity.
deleted 7y ago
[deleted]
rzzzt 7y ago
I always think of it as a peristaltic pump: big tube, squeeze one side, squeeze the other to circulate blood. This paper might be of interest: "A review of selected pumping systems in nature and engineering--potential biomimetic concepts for improving displacement pumps and pulsation damping" https://www.ncbi.nlm.nih.gov/pubmed/26335744 https://www.ncbi.nlm.nih.gov/pubmed/26335744
- 01100011 7y ago
  From the paper I was thinking of(link added to parent comment): "the velocity of the blood in the embryonic heart lumen exceeds the speed of the peristaltic wave moving through the lumen" which is interesting if you think of the heart as a peristaltic pump.
ultrarunner 7y ago
I routinely (especially in the summer in the Southwest) experience near immediate hypotension after finishing a (running) race. The last time it happened, the medic explained that my legs add significant circulatory capacity— when they’re moving. I now walk around after races until vasoconstriction happens, and I fair much better. I don’t know enough to corroborate the ram pump theory, but I don’t doubt that there are other mechanisms aiding circulation
- 01100011 7y ago
  Sorry, I was hoping my insertion of the word 'generally' implied that it wasn't the only driver of circulation in all circumstances. Yes, there are check valves in the circulatory system and peripheral muscle contractions contribute as well, but comatose people don't, as far as I know, die because their muscles aren't contracting. The body doesn't seem to require peripheral muscle contractions to circulate blood.

thaumasiotes 7y ago

> The general consensus is that the heart is a pump and generally the sole driver of circulation in mammals. It's certainly not the general consensus that the heart is the sole driver of circulation in mammals. Your heart drives the flow of blood out through your arteries; it's much less effective at driving blood back through your veins.

TheSpiceIsLife 7y ago
Veins contain one-way valves, so veinous return is aided by movement and muscle contraction. The lymphatic system doesn’t have a pump at all and is entirely driven by movement + muscle contraction + fluid pressure as a result of tissue integrity.

deleted 7y ago

[deleted]

rzzzt 7y ago

I always think of it as a peristaltic pump: big tube, squeeze one side, squeeze the other to circulate blood. This paper might be of interest: "A review of selected pumping systems in nature and engineering--potential biomimetic concepts for improving displacement pumps and pulsation damping" https://www.ncbi.nlm.nih.gov/pubmed/26335744 https://www.ncbi.nlm.nih.gov/pubmed/26335744

01100011 7y ago
From the paper I was thinking of(link added to parent comment): "the velocity of the blood in the embryonic heart lumen exceeds the speed of the peristaltic wave moving through the lumen" which is interesting if you think of the heart as a peristaltic pump.

ultrarunner 7y ago

I routinely (especially in the summer in the Southwest) experience near immediate hypotension after finishing a (running) race. The last time it happened, the medic explained that my legs add significant circulatory capacity— when they’re moving. I now walk around after races until vasoconstriction happens, and I fair much better. I don’t know enough to corroborate the ram pump theory, but I don’t doubt that there are other mechanisms aiding circulation

01100011 7y ago
Sorry, I was hoping my insertion of the word 'generally' implied that it wasn't the only driver of circulation in all circumstances. Yes, there are check valves in the circulatory system and peripheral muscle contractions contribute as well, but comatose people don't, as far as I know, die because their muscles aren't contracting. The body doesn't seem to require peripheral muscle contractions to circulate blood.