Is the Flow in the Giraffe’s Jugular Vein a “Free” fall?
There is a 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 jugular vein is collapsed