branchial heart

{{short description|Accessory pump found in the heart of some cephalopods}}

Image:Chtenopteryx sicula2.jpg, showing the presence of the branchial hearts.]]

Branchial hearts are accessory pumps that supplement the action of the systemic heart in a cephalopod's body. They are myogenic in nature.{{cite journal|title=The role of the branchial heart complex in circulation of coleoid cephalopods|year=1987|doi=10.1007/BF02143583|last1=Fiedler|first1=A.|last2=Schipp|first2=R.|s2cid=3165383|journal=Experientia|volume=43|issue=5|pages=544–553}} Branchial hearts are always in pairs located at the base of the gills. Each branchial heart consists of a single chamber.[http://tolweb.org/notes/?note_id=587 Cephalopoda Glossary]. Tree of Life web project. They pump blood through the gills via the afferent branchial veins. Since they only circulate venous blood, branchial hearts function under predominantly anaerobic conditions. Branchial hearts also appear to be involved in hemocyanin synthesis.{{cite journal|title=Cytobiological studies on hemocyanin metabolism in the branchial heart complex of the common cuttlefish Sepia officinalis (Cephalopoda, Dibranchiata)|year=1998|doi=10.1007/s004410051088|last1=Beuerlein|first1=K.|last2=Schimmelpfennig|first2=Robert|last3=Westermann|first3=Bettina|last4=Ruth|first4=Peter|last5=Schipp|first5=Rudolf|s2cid=33065779|journal=Cell and Tissue Research|volume=292|issue=3|pages=587–595|pmid=9582416}}

Each branchial heart is directly connected to a branchial heart appendage or pericardial gland.{{cite journal|title=The fine structure of the branchial heart appendage of the cephalopod Octopus dofleini martini|year=1973|volume=136|issue=4|doi=10.1007/BF00307370|last1=Witmer|first1=Astrid|last2=Martin|first2=Arthur W.|s2cid=27050110|journal=Zeitschrift für Zellforschung und Mikroskopische Anatomie|pages=545–68|pmid=4346672}} The action of the branchial hearts is necessary for the production of primary urine in these appendages via pressure filtration.{{cite journal|title=Comparative cytochemical and pharmacological studies on the cholinergic innervation of the branchial heart of the cephalopod Sepia officinalis (L.)|year=1986|doi=10.1007/BF01975878|last1=Schipp|first1=R.|last2=Schmidt|first2=H. R.|last3=Fiedler|first3=A.|s2cid=19161306|journal=Experientia|volume=42|pages=23–30}} Branchial hearts may have evolved from the pericardial glands of nautiloids, such as those still found in modern nautiluses.{{cite journal|title=Nautilus pompilius: branchial circulation enhanced by an auxiliary pumping mechanism|year=1977|volume=33|issue=11|doi=10.1007/BF01918802|last1=Bourne|first1=G. B.|last2=Redmond|first2=J. R.|last3=Johansen|first3=K.|s2cid=33164113|journal=Experientia|page=1453|doi-access=free}}