🚀 go-pugleaf

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."