2
Dynamics
of
the
Vascular System
Additionally, in the Galenic view, blood was passed from the right side
of the heart to the
left
side through pores, which
was
later shown
to
be
incorrect
as
they
do not exist within the ventricular
septum, as
demonstrated
by
Columbus
(1 5 16-1 559),
a
Belgian
anatomist.
Columbus, during his many dissections, confirmed that venous blood of
the right ventricle passed into the left ventricle through the lungs. This
was concluded
a
few years earlier by Servetus (1511-1553), a Spanish
theologian and physician. Thus, the open-circuit interpretation of the
circulation by Galen cannot accurately describe the “circulation
of
blood”.
In his many teachings, though some aspects were later known to be
erroneous, Galen was the first to recognize that the walls of arteries are
thicker than those of the veins and that arteries were connected to veins.
It was the Persian physician
Ibn
an-Nafis (1210-1288) who claimed that
venous blood of the right ventricle is carried by the artery-like vein into
the lungs, where it mixes with the air and then into the left ventricle
through vein-like artery.
Galilei (1564-1642) in his “Dialogue
of
the Two Sciences”, which
appeared in 1637, suggested the circulation of blood in
a
closed system.
Centuries later today, the idea of the circulation of blood was credited to
William Harvey (1578-1657), a contemporary of Galilei, in his now
famous “De Motu Cordis and De Circulatione
Sanguinis” (1 628)
presented to King Charles. He described in his “Anatomical Exercises”
that “blood does continually passes through the heart” and that “blood
flow continually out the arteries and into the veins”. Harvey’s work
indicated the pulsatile nature of blood as a consequence of intermittent
inflow, during roughly one-third of the heart cycle, now known as
systole, in combination with essentially steady outflow through the
periphery during the remaining cardiac period, the diastole.
Harvey’s work was completed before Malphighi who worked with
the aid of
a
compound microscope. He reported in 166 1 the discovery of
the capillaries linking the arterial circulation to the venous circulation,
while he was working with the microscopic anatomy of the pulmonary
parenchyma in the frog, a uni-ventricular amphibian.
Dutch anatomist
Van Leeuwenhoek
(1
632- 1723) confirmed the capillaries in different
organs of several animal species and established the concept
of
the
