The Cardiovascular System: Blood Vessels
their companion arteries. Superﬁcial veins run just beneath
the skin and are readily seen, especially in the limbs, face,
and neck. Because there are no superﬁcial arteries, the names
of the superﬁcial veins do not correspond to the names of
any of the arteries.
Venous pathways are more interconnected.
Unlike the fairly
distinct arterial pathways, venous pathways tend to have nu-
merous interconnections, and many veins are represented by
not one but two similarly named vessels. As a result, venous
pathways are more diﬃcult to follow.
The brain and digestive systems have unique venous drain-
Most body regions have a similar pattern for
their arterial supply and venous drainage. However, the
venous drainage pattern in at least two important body ar-
eas is unique. First, venous blood draining from the brain
dural venous sinuses
rather than typical veins.
Second, blood draining from the digestive organs enters a
special subcirculation, the
hepatic portal system
, and perfuses
through the liver before it reenters the general systemic cir-
culation (see Table 19.12).
Principal Vessels of the
Name and give the location of the major arteries and veins
in the systemic circulation.
Describe the structure and special function of the hepatic
Except for special vessels and shunts of the fetal circulation (de-
scribed in Chapter 28), the principal arteries and veins of the sys-
temic circulation are described in
Notice that by convention, oxygen-rich blood is shown red,
while blood that is relatively oxygen-poor is depicted blue,
regardless of vessel type. ±e schematic ﬂowcharts (pipe dia-
grams) that accompany each table show the vessels that would
be closer to the viewer in brighter, more intense colors than ves-
sels deeper or farther from the viewer. For example, darker blue
veins would be closer to the viewer than lighter blue veins in the
body region shown.
Blood Vessels of the Body
The Two Main Circulations
of the Body
Trace the pathway of blood through the pulmonary circuit,
and state the importance of this special circulation.
Describe the general functions of the systemic circuit.
is o²en used to describe the body’s
complex network of blood vessels. However, the heart is actu-
ally a double pump that serves two distinct circulations, each
with its own set of arteries, capillaries, and veins. ±e
is the short loop that runs from the heart to
the lungs and back to the heart. ±e
blood through a long loop to all parts of the body before re-
turning it to the heart.
on pp. 722–723 shows both
Systemic Arteries and Veins:
Differences in Pathways
As we saw in Chapter 18, the heart pumps all of its blood into a
single systemic artery—the aorta. In contrast, blood returning
to the heart is delivered largely by two terminal systemic veins,
the superior and inferior venae cavae. ±e single exception to
this is the blood draining from the myocardium of the heart,
which is collected by the cardiac veins and reenters the right
atrium via the coronary sinus.
In addition to these diﬀerences between arteries and veins
connecting to the heart, there are three important diﬀerences
between systemic arteries and veins:
Arteries run deep while veins are both deep and superﬁcial.
Deep veins parallel the course of the systemic arteries and
both are protected by body tissues along most of their course.
With a few exceptions, these veins are named identically to
(Text continues on p. 745.)