© 1968 by The Society for Integrative and Comparative Biology
Functional Morphology of the Heart in Mammals
Chicago Zoological Park Brookfield, Illinois, 60513
Lincoln Park Zoological Gardens Chicago, Illinois
The heart in all mammals is composed of four separate chambers and in broad outline is very similar in monotremes, marsupials, and placental mammals. The functional anatomy of the chambers and valves of the dog's heart has been investigated by Rushmer (1961) and others. They concluded that the atria serve as reservoirs and the ventricles as reciprocating pumps, the right ventricle being a volume pump and the left ventricle a pressure pump. Similar investigations in man, horses, cattle, sheep, and goats suggest that other mammalian hearts act in the same way.
However, there is a wide range of variation in heart weight relative to body weight, in heart shape, and in minor points of internal anatomy. The general contention in this paper is that these differences should be considered functionally significant unless proven otherwise. Certain morphological structures such as the valves of the posterior vena cava, Lower's tubercle, the atrial appendages, and the more extreme forms of double ventricular apex may not have functional significance. Verbal descriptive anatomy has probably reached the end of its usefulness and should be replaced with measurements. A correlation of quantitative anatomy and hemodynamics would seem to be the most promising line of future research.