Re: [math-fun] Why we have red blood cells: not turtles all the way down
On this topic, I remember c. 8th grade being shown a film addressing this topic, that concluded the lenticular shape of the red blood cell — i.e., its hourglass cross=section — was exactly what some computer simulation showed was ideal (for exactly what conditions, I don't recall). I later learned that the film was funded by a possibly biased organization, and even so I don't know if those claims stand the test of time (c. 58 years since 8th grade). —Dan ----- ... why we had red blood cells ... ... -----
A quick Google search finds this page, which cites biological advantages to sequestering hemoglobin within red blood cells. -- Gene On Friday, October 12, 2018, 5:18:45 PM PDT, Dan Asimov <dasimov@earthlink.net> wrote: On this topic, I remember c. 8th grade being shown a film addressing this topic, that concluded the lenticular shape of the red blood cell — i.e., its hourglass cross=section — was exactly what some computer simulation showed was ideal (for exactly what conditions, I don't recall). I later learned that the film was funded by a possibly biased organization, and even so I don't know if those claims stand the test of time (c. 58 years since 8th grade). —Dan ----- ... why we had red blood cells ... ... -----
A quick Google search finds this page, which cites biological advantages to sequestering hemoglobin within red blood cells. Sorry about the first post. https://biology.stackexchange.com/questions/73309/why-isn-t-haemoglobin-a-pl... -- Gene On Friday, October 12, 2018, 5:18:45 PM PDT, Dan Asimov <dasimov@earthlink.net> wrote: On this topic, I remember c. 8th grade being shown a film addressing this topic, that concluded the lenticular shape of the red blood cell — i.e., its hourglass cross=section — was exactly what some computer simulation showed was ideal (for exactly what conditions, I don't recall). I later learned that the film was funded by a possibly biased organization, and even so I don't know if those claims stand the test of time (c. 58 years since 8th grade). —Dan ----- ... why we had red blood cells ... ... ----- _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
Re: https://biology.stackexchange.com/questions/73309/why-isn-t-haemoglobin-a-pl... Eugene's link is interesting, but IMHO toxicity is a 2nd order effect: why worry about toxicity w/o the primary effect of enhancing oxygen delivery? Getting oxygen to cells far from the surface is essential to making large animals. Putting hemoglobin into discrete little packages helps enormously. As an aside, last January right here in Santa Barbara we had a rather dramatic demonstration of solid particles moving in a fluid flow ("debris flow"), when mud with nearly the density of rock enabled the motion of large boulders the size of automobiles to move at tens of miles/hour and destroy quite a number of homes (Google Montecito debris flows). I thought of another major reason for RBC's: most places plasma wants to go -- e.g., lymphatic system, interstitial volumes, etc. -- don't need (or perhaps don't want) oxygen. And that plasma hangs out for hours, days, months, w/o ever getting back to the lungs or kidneys. So whatever hemoglobin spends its time there is wasted and in a depleted oxygen state. Mare that my analysis only raises new questions -- e.g., what about the transport of CO2 *away from* the tissues and back to the lungs, where it can be exhaled? How come there isn't an equivalent mechanism analogous to RBC's for this transport? (Probable answer: it's much easier to *buffer* the bad effects of CO2 -- e.g., pH lowering -- than it is to bring in new oxygen. Indeed, in some cold-blooded animals, CO2 transport out of the body isn't very efficient at all -- leading to the sluggish behavior of these animals most of the time. For example, turtles (!) effectively capture and deposit CO2 into their shells during the long winter, so they don't have to bother "breathing" to get rid of it.) I haven't yet looked at the literature&patents on *synthetic blood*. Since oxygen-carrying capacity is one of the foremost in the requirements for synthetic (whole) blood, it would be interesting to see how those researchers are faring in their quest. At 05:38 PM 10/12/2018, Eugene Salamin via math-fun wrote:
A quick Google search finds this page, which cites biological advantages to sequestering hemoglobin within red blood cells.
Sorry about the first post.
https://biology.stackexchange.com/questions/73309/why-isn-t-haemoglobin-a-pl...
-- Gene
On Friday, October 12, 2018, 5:18:45 PM PDT, Dan Asimov <dasimov@earthlink.net> wrote:
On this topic, I remember c. 8th grade being shown a film addressing this topic, that concluded the lenticular shape of the red blood cell  i.e., its hourglass crross=section  was exactly what some computer simulationn showed was ideal (for exactly what conditions, I don't recall).
I later learned that the film was funded by a possibly biased organization, and even so I don't know if those claims stand the test of time (c. 58 years since 8th grade).
ÂDan ----- ... why we had red blood cells ... ... -----
participants (3)
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Dan Asimov -
Eugene Salamin -
Henry Baker