18
Dynamics
of
the
Vascular
System
2.1.3
The Arteries
Anatomical descriptions of the human and other mammalian vascular
trees can be found in many textbooks. For the purpose of illustrating the
blood perfusion and pressure pulse transmission path, the major branches
of the arterial tree are shown in Fig.
2.1.3.
There are considerable
similarities among the corresponding
anatomical sites of the mammalian arterial circulation (Li,
1996).
The
root of the aorta begins immediately at the aortic valve. The outlet of the
valve sits the ascending aorta having the largest diameter. The first
branching off the aorta are the left and right main coronary arteries. The
aortic arch junction
is
formed by the ascending aorta, the brachiocephalic
artery, the left subclavian artery, and the descending thoracic aorta.
There are numerous branches come off the descending aorta at right
angles, renal arteries which perfuse the kidneys are such examples. The
distal end of the descending aorta is the abdominal aorta which forms the
aorto-iliac junction with left and right iliac arteries and its continuation.
In the human, it
is
a bifurcation. The femoral artery, a well-known
peripheral artery, because
of
its accessibility, continues from the iliac
artery. These are the arteries perfusing the upper thighs, with the tibia1
arteries peruse the lower legs. The aorta has, comparatively speaking, the
greatest geometric taper, with its diameter decreasing with increasing
distance away from the ventricle. The common carotid arteries are the
longest, relatively uniform vessels, with the least geometrical tapering.
The brachial arteries perfusing the upper arms lead to distal radial
arteries. Both brachial and radial arteries are the most common sites for
noninvasive blood pressure monitoring.
2.
I.4
The Veins
Arteries deliver blood from the ventricles to vascular beds, while veins
return it to the atria. Veins, unlike arteries are generally thin-walled and
have low distending pressures. They are collapsible even under normal
conditions
of
blood pressure pulsation.
The inferior vena cava is the main trunk vein. The superior vena cava
feeds into the right atrium and the main pulmonary vein leads into the
left atrium with oxygen-enriched blood.
