Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!asuvax!mcdphx!udc!cmccaff From: cmccaff@urbana.mcd.mot.com (Chuck McCaffrey) Newsgroups: sci.bio Subject: Re: Honeycombs and mRNA Message-ID: Date: 4 Apr 90 17:23:26 GMT References: <19792@eerie.acsu.Buffalo.EDU> <1209@ccadfa.adfa.oz.au> <7074@uhccux.uhcc.hawaii.edu> <19891@eerie.acsu.Buffalo.EDU> <5029@ucrmath.UCR.EDU> <1990Mar29.182735.28498@Solbourne.COM> <3954@plains.UUCP> <1990Apr2.191538.8552@Solbourne.COM> Sender: netnews@urbana.mcd.mot.com Organization: Motorola Microcomputer Division, Urbana [IL] Design Center Lines: 38 In-reply-to: taylor@anthrax.Solbourne.COM's message of 2 Apr 90 19:15:38 GMT In article <1990Apr2.191538.8552@Solbourne.COM> taylor@anthrax.Solbourne.COM (Dick Taylor) writes: In article <3954@plains.UUCP> jarvi@plains.UUCP (Trent BIOLOGICAL Jarvi) writes: >... >Is it possible that the heart is another 'lobe' of the lungs? >That still would not explain the question about the heart being on the left > >Trent Jarvi ivraJ tnerT It would seem unlikely. The heart, after all, is different in structure, function, and connection to the outside world. It was interesting (and a good way of remembering which lung had how many lobes) to note that the tricuspid valve (between the right atrium and right ventricle of the heart) has three lobes, where the mitral valve (between the left atrium and left ventricle) has two. Does anyone else know of 3:2 asymmetries in the body? Are they also 3-right/2-left? ---- The heart also comes from different embryologic tissue. While it is true that the tricuspid valve (right side) has three cusps (hence its name) and the mitral valve (left side) has two cusps (it is also known as the bicuspid valve), I don't believe that this 3:2 structure is more than coincident with the fact that the right lung has three lobes and the left lung has two lobes. The left lung has an underdeveloped third lobe anyway, called the lingula. My embryology and anatomy are dim and distant, so the following conjecture is suspect, but I seem to recall that the heart folds and rotates as it develops in the embryo, as do many other organs in the thorax and abdomen. I further seem to recall that the heart can end up in the right side of the chest every 1 in N births, N being a very large integer. I distinctly remember listening to the heartsounds of a right-sided heart in a patient way back in medical school. (Please note that I did not finish medical school and am thus not an MD. I sampled med school and chose a different path.) -- Chuck McCaffrey cmccaff@urbana.mcd.mot.com 1101 E University Urbana IL 61801 217-384-8585 The opinions are mine. The facts belong to everyone. "If it were done when 'tis done, then't were well it were done bermspicfully."