[Histonet] Lab Week-Histology Trivial or Fun Facts LONG OFF TOPIC

[koellingr <@t> comcast.net]

Hi in grad school taking microanatomy and pathology classes, 2 that I heard are this:  The surface area of all the alveoli in the lungs of an adult is between 40-70 square meters. That seems reasonable in having a 40-70 square meter surface (where all gas exchange takes place) represent all the gas exchange in lungs. Have seen that figure numerous times so while can't test it, can believe it.  The other one that I also can't test and is hard to believe is that the sum total length of all vessels (large small, artery vein down to every single capillary) in one adult measures about 100,000 kilometers (62,000 miles). Again there are many disparate medical and anatomical references so either all right or all wrong. 



The 2 micron sectioned egg I don't believe. (1) There are 25,400 microns in an inch. A 2 inch long egg is about 50,000 microns long. At 2 microns per section thats about 25,000 egg sections.  Even is each section is 2 square inches (that's generous since each end isn't close to 2 squre inches in area), thats 100,000 square inches. At 1,296 square inches per square yard, that's about 40 square yards which is far short of a football field (100 yards x 53 yards). (2) If you calculate the volume of a "solid rectangle" covering a football feild that is 100 yards x 53 yards x 2 microns and of course converting all to yards or microns, the answer is a specific volume.  If you take the volume of an ellipsoid which is four thirds times pi times a times b times c with a, b and c being the lenggth of the 3 axis of the ellipsoid, and using approximate measurements for the egg, I come up with far , far less volume in egg than in the "rectangular solid" covering football field. (3) This is a classical calculus definte integral washer problem. Whether this egg as an ellipsoid is scalene, oblate or prolate, integrating volume over the limits of integration gives me much, much less volume than is needed to cover a football field 2 microns thick.  Have tried all 3 methods and converting everything to  microns or yards using scientific notation. So 6 calculations.  Everytime I come up somewhere close to the area of 2 micron slices covering approximately 1/100 of the football field. 



Unless my math is all wrong, or this is a humongous, enormous ostrich and not chicken egg. 



Ray 

Raymond Koelling 

PhenoPath Labs 

Seattle, WA 


----- Original Message ----- 
From: "Disher Lori" <Lori.Disher <@t> HCAhealthcare.com> 
To: histonet <@t> lists.utsouthwestern.edu 
Sent: Tuesday, April 14, 2009 12:12:40 PM GMT -08:00 US/Canada Pacific 
Subject: [Histonet] Lab Week-Histology Trivial or Fun Facts 

Hello, 
  I was wondering if anyone has some histo trivial-fun facts to share for Lab Week?  I remember a supervisor told me long ago that she was told while in training, that if you took a hard boilded egg and sectioned it at 2 microns you would have enough sections to cover a football field.  Has anyone ever heard that one before?  Can anyone contribute any others?  We are trying to come up with some games for lab week. 
Lori 

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