The
ancient Greek physician Galen, well-acquainted with the circulatory system,
believed that blood flowed within dedicated vessels. He posited that arteries
carried bright, oxygenated blood, while veins contained dark, deoxygenated
blood, each serving distinct functions. Galen's teachings, though flawed,
persisted for nearly a millennium, perpetuating the misconception that blood
moved from the right ventricle to the left side, where it absorbed air and
subsequently circulated through the body.
In
1242, the Arabian physician Ibn al-Nafis made a groundbreaking correction in
his work "Commentary on the Anatomy of Canon of Avicenna." He
accurately described pulmonary blood circulation, emphasizing the absence of
pores or direct connections between the lower heart chambers. Instead, he
proposed a path where blood flowed from the pulmonary artery to the lungs,
where it mingled with air before journeying through the pulmonary vein to the
left side of the heart, finally distributing throughout the body. He also
foresaw the existence of pores between the pulmonary artery and vein, a
prophecy validated centuries later when Italian microscopist Marcello Malpighi
first visualized capillaries.
The
Spanish theologian and physician Michael Servetus provided an accurate account
of pulmonary circulation in his theological work, "Restoration of
Christianity" (1553), despite it not being a scientific or medical text.
Regrettably, this crucial insight was largely overlooked, and only three copies
of the work remain. Tragically, what was believed to be the last copy and its
author met a grim fate in Geneva, 1553, as John Calvin ordered their burning at
the stake. This act was a response to Servetus's "heretical" writings
and his rejection of the Trinity and infant baptism.
Realdo
(also Realdus) Colombo, an Italian anatomist and contemporary of Michelangelo,
made significant anatomical discoveries, including the pivotal identification
of the pulmonary circuit in the 1550s. He proposed a concept where venous
(oxygen-deficient) blood journeyed from the heart to the lungs, mixed with air,
and then returned to the heart. Colombo's revelation greatly contributed to
William Harvey's subsequent description of blood circulation in his 1628 work,
"De Motu Cordis."
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| In 1553, Michael Servetus, a Spanish physician and theologian, met a gruesome end as he was executed by burning at the stake along with his own books. Among the condemned texts was his "heretical" theological treatise, "Restoration of Christianity," notable for its early and precise description of pulmonary circulation. |
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