Badeer H S
Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA.
Comp Biochem Physiol A Physiol. 1997 Nov;118(3):573-6. doi: 10.1016/s0300-9629(96)00376-3.
There is controversy as to whether or not the heart works against gravity in the arteries to the head in the upright position. One view is that the gravitational effects in the neck arteries are counterbalanced by the gravitational effects in the veins of the neck and the heart does not do extra pressure work. This concept has been challenged by others who claim that the heart works against gravity based on the notion that the jugular vein is collapsed and gravitational effects on jugular blood are inoperative, similar to the "free" fall of liquids. The present study supports the view that blood flow in the collapsible jugular vein of the giraffe is not a "free" fall and that the heart does not spend extra energy to raise the blood to the head.
关于在直立姿势下心脏是否在向头部供血的动脉中对抗重力工作存在争议。一种观点认为，颈部动脉中的重力效应被颈部静脉中的重力效应抵消，心脏不做额外的压力功。这一观点受到了其他人的挑战，他们认为基于颈静脉塌陷以及重力对颈静脉血液不起作用的观点，心脏是在对抗重力工作，类似于液体的“自由”下落。本研究支持这样一种观点，即长颈鹿可塌陷颈静脉中的血流不是“自由”下落，并且心脏不会花费额外能量将血液提升至头部。
