The circulation of the blood
This page delivers no verdict; it presents claims and evidence with their sources. No theory in science is absolute. Method
For everyone
According to Galen, blood was continually produced in the liver and consumed in the body. In 1628 William Harvey, by calculating the amount of blood the heart pumps, argued that blood circulates continuously in a loop. The pulmonary circulation had been described in the 13th century by the Damascene physician Ibn al-Nafīs.
For specialists
Harvey's quantitative argument: if the heart pumps about half an ounce (≈15 g) per beat, in half an hour it pumps more than all the blood in the body, far more than food could produce. The capillaries themselves could not be seen in Harvey's time and were observed microscopically by Malpighi in 1661. In his Commentary on the Anatomy of the Canon, Ibn al-Nafīs wrote that there are no pores in the septum between the ventricles, as Galen had claimed, and that the blood passes through the lungs.
Claims
- Blood circulates in a closed loop, pumped by the heart through arteries and veins.[1]
Evidence
Supporting
The quantity of blood the heart pumps in a short time far exceeds what the body could produce, so the blood must return and be reused.[1]
Ligature experiments on the arm showed that blood in the veins flows only toward the heart.[1]
The pulmonary circulation had been described in the 13th century by Ibn al-Nafīs.[2]
Challenging
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Connections
Parent
MedicineThis topic is a stop on these journeys
Sources
- Book (1628). Exercitatio Anatomica de Motu Cordis et Sanguinis in Animalibus. William Fitzer, Frankfurt
- Article (2008). Ibn al-Nafis, the pulmonary circulation, and the Islamic Golden Age. Journal of Applied Physiology 105(6), 1877–1880DOI 10.1152/japplphysiol.91171.2008archive
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Cite this page
Athena contributors. (2026). The circulation of the blood. Athena: The tree of human knowledge. Retrieved November 1, 2026, from https://latifkedi.github.io/athena/en/d/harvey/
@misc{athena_harvey,
title = {The circulation of the blood},
author = {{Athena contributors}},
year = {2026},
howpublished = {\url{https://latifkedi.github.io/athena/en/d/harvey/}},
note = {Athena: The tree of human knowledge. Accessed: 2026-11-01}
}Added: September 27, 2026 · Last changed: September 27, 2026 · Page history