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Natural Science Forum / Biology / Biology / February 2004How many animal types have hearts on the right side? Humans with right hearts
I'm very curious. Do *any* animals have hearts on the right side? This may include even fish, ocean floor volcanic ecosystem lifeforms, even insects (although I know some insects don't even have hearts). Is there a reason for the heart being on the left? I mean, if nature had no reason, why shouldn't it sort of distributed? Is it perhaps something to do with molecular chirality? That is, it just so happens that because of the molecular chirality of the dominant lifeforms on our planet, that for the heart to be on the left, is more energy efficient? Do "mutants", humans with hearts on the right, tend to have different characteristics, tendancies, lifespans than normal humans? Just curious! Thanks a lot for your answers! >I'm very curious. > [quoted text clipped - 13 lines] > >Just curious! Thanks a lot for your answers! The heart is really central. It is just that, by chance, the left side pumps blood to the body (systemic loop) while the right side pumps blood to the lungs (pulmonary loop). The systemic loop is a high pressure system, the pulmonary loop is a low pressure system so the left side does significantly more physical work than the right and has a much larger muscle mass. Animals other than mammals tend to have much more bilaterally symmetric vascular systems. Insects and other arthropods have completely central bilaterally symmetric hearts. Earthworms have pumping systems called hearts bilaterally arranged. Mollusc hearts are also centrally located. > I'm very curious. > > Do *any* animals have hearts on the right side? This may include even > fish, ocean floor volcanic ecosystem lifeforms, even insects (although I > know some insects don't even have hearts). In most organism heart is located centrally with a bilaterally symmetrical vascular system. > Is there a reason for the heart being on the left? The left sided heart (& right sided liver) in mammals is caused by a particular type of rotation of the embryonic foregut. > Do "mutants", humans with hearts on the right, tend to have different > characteristics, tendancies, lifespans than normal humans? Yes. There are two related conditions. One is called Situs Inversus in which all the thoracic & abdominal organs are on the opposite side related to normal and the other one is called Dextrocardia, in which only the heart is misplaced. Both are caused by structural abnormality of some intracellular organelle. Some such people do suffer from various ailments, such as repeated bronchitis, bronchiectasis, etc. because the cellular defect reduces the efficacy of the cilliary movement of the epithelial cells, which in turn impairs the ability to clear the respiratory tree from mucus.  SignatureGautam Majumdar Please send e-mails to gmajumdar@freeuk.com > > I'm very curious. > > [quoted text clipped - 22 lines] > epithelial cells, which in turn impairs the ability to clear the > respiratory tree from mucus. i thought there were also twins who have their internal organs mirored in one another? is that also callde situs inversus? >> Yes. There are two related conditions. One is called Situs Inversus in >> which all the thoracic & abdominal organs are on the opposite side [quoted text clipped - 8 lines] > i thought there were also twins who have their internal organs mirored > in one another? is that also callde situs inversus? I am not sure what you meant. Unless there is some developmental anomaly, twins usually grow separately and normally. Various types of conjoint twins, such as Siamese Twins, may have all sorts of abnormalities. These are not called situs inversus. I don't know whether each such anomaly have a special name or not. They may very well have. Situs inversus is applied specifically to the condition where all the organs derived from the embryonic gut are on the opposite side compared to their normal location. During normal development the embryonic gut rotates to the left (i.e., the structures developing from its anterior wall go to the left) & in situs inversus they go to the right. SignatureGautam Majumdar Please send e-mails to gmajumdar@freeuk.com >>> Yes. There are two related conditions. One is called Situs Inversus in >>> which all the thoracic & abdominal organs are on the opposite side [quoted text clipped - 20 lines] >rotates to the left (i.e., the structures developing from its anterior >wall go to the left) & in situs inversus they go to the right. R. Schenck is probably thinking about mirror twins, identical twins that show varying degrees of mirror symmetry such as handedness, direction of hair whorl, etc. This can occur if the zygote splits on a particular axis separating left and right sides of an embryo. Although conjoined twins do sometimes have symmetric organ placement, one with situs inversus, I can't find information about how often it may occur in identical twins or even mirror identical twins. >>>> Yes. There are two related conditions. One is called Situs Inversus >>>> in which all the thoracic & abdominal organs are on the opposite side [quoted text clipped - 28 lines] > inversus, I can't find information about how often it may occur in > identical twins or even mirror identical twins. Ah, that's it. Of course, situs inversus like feature has been reported in mirror twins. But in mirror twins this condition is called situs viscerum specularis. That is because true situs inversus is caused by some kind of structural defect of the microtubules which control the ciliary movement required for the proper rotation of the embryonic gut. In situs viscerum specularis there is no defect of the microtubules. The inversion occurs because the zygote splits after the bilateral symmetry is lost, i.e., after left-right differentiation has occured. In most mirror twins only the ectodermal structures show the mirror symmetry, though. Ref:Gedda L, et al, Situs viscerum specularis in monozygotic twins, Acta Genet Med Gemellol (Roma). 1984;33(1):81-5 SignatureGautam Majumdar Please send e-mails to gmajumdar@freeuk.com >Situs inversus is applied specifically to the condition where all the >organs derived from the embryonic gut are on the opposite side compared >to their normal location. During normal development the embryonic gut >rotates to the left (i.e., the structures developing from its anterior >wall go to the left) & in situs inversus they go to the right. Minor correction - the ciliary defect that causes situs inversus actually randomizes the direction of the rotation, so half the people with the defect have situs inversus per se, and the other half have all the other problems except the reversal of the position of the organs. On Sun, 01 Feb 2004 17:21:20 +0000, bae wrote: >>Situs inversus is applied specifically to the condition where all the >>organs derived from the embryonic gut are on the opposite side compared [quoted text clipped - 6 lines] > with the defect have situs inversus per se, and the other half have all > the other problems except the reversal of the position of the organs. Exactly. Thanks for clarifying the point. SignatureGautam Majumdar Please send e-mails to gmajumdar@freeuk.com > >>>> Yes. There are two related conditions. One is called Situs Inversus > >>>> in which all the thoracic & abdominal organs are on the opposite side [quoted text clipped - 41 lines] > Ref:Gedda L, et al, Situs viscerum specularis in monozygotic twins, Acta > Genet Med Gemellol (Roma). 1984;33(1):81-5 damnit, now i can't make fun of one of my buddies who is a twin for being mirrored on the inside! |
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