742
UNIT 4
Maintenance of the Body
19
Table 19.12
Veins of the Abdomen
Te
inferior vena cava
returns blood from the abdominopelvic
viscera and abdominal walls to the heart
(Figure 19.29a)
. Most
of its venous tributaries have names that correspond to the ar-
teries serving the abdominal organs.
Veins draining the digestive viscera empty into a common
vessel, the
hepatic portal vein
, which transports this venous
blood into the liver before it is allowed to enter the major sys-
temic circulation via the hepatic veins (Figure 19.29c). Such a ve-
nous system—veins connecting two capillary beds together—is
called a
portal system
and always serves very specific needs. Te
hepatic portal system
carries nutrient-rich blood (which may
also contain toxins and microorganisms) from the digestive or-
gans to the liver, where it can be “treated” before it reaches the
rest of the body. As the blood percolates slowly through the liver
sinusoid capillaries, hepatocytes process nutrients and toxins,
and phagocytic cells rid the blood of bacteria and other foreign
matter. Te veins of the abdomen are listed in inferior to supe-
rior order.
Description and Areas Drained
Lumbar veins.
Several pairs of lumbar veins drain the
posterior abdominal wall. Tey empty both directly into
the inferior vena cava and into the ascending lumbar
veins of the azygos system of the thorax.
Gonadal (testicular or ovarian) veins.
Te right gonadal
vein drains the ovary or testis on the right side of the body
and empties into the inferior vena cava. Te le± gonadal
vein drains into the le± renal vein superiorly.
Renal veins.
²he right and left renal veins drain the
kidneys.
Suprarenal veins.
Te right suprarenal vein drains the
adrenal gland on the right and empties into the inferior
vena cava. Te le± suprarenal vein drains into the le± re-
nal vein.
Hepatic portal system.
Like all portal systems, the hepatic
portal system is a series of vessels in which two separate cap-
illary beds lie between the arterial supply and the final ve-
nous drainage. In this case, the first capillary beds are in the
stomach and intestines and drain into tributaries of the he-
patic portal vein, which brings them to the second capillary
bed in the liver. Te short
hepatic portal vein
begins at the
L
2
level. Numerous tributaries from the stomach and pan-
creas contribute to the hepatic portal system (Figure 19.29c),
but the major vessels are as follows:
Superior mesenteric vein:
Drains the entire small in-
testine, part of the large intestine (ascending and trans-
verse regions), and stomach.
Splenic vein:
Collects blood from the spleen, parts of
the stomach and pancreas, and then joins the superior
mesenteric vein to form the hepatic portal vein.
Inferior mesenteric vein:
Drains the distal portions
of the large intestine and rectum and joins the splenic
vein just before that vessel unites with the superior
mesenteric vein to form the hepatic portal vein.
Hepatic veins.
Te right, le±, and middle hepatic veins
carry venous blood from the liver to the inferior vena cava.
Cystic veins.
Te cystic veins drain the gallbladder and
join the portal veins in the liver.
Inferior phrenic veins.
Te inferior phrenic veins drain
the inferior surface of the diaphragm.
(a) Schematic flowchart.
Inferior
vena cava
Inferior phrenic veins
Hepatic veins
Hepatic portal vein
Superior mesenteric vein
Splenic vein
Inferior
mesenteric
vein
L. ascending
lumbar vein
External iliac vein
Common iliac veins
R. ascending
lumbar vein
Gonadal veins
Renal veins
Suprarenal
veins
Lumbar veins
Hepatic
portal
system
Cystic vein
Internal iliac veins
Figure 19.29
Veins of the abdomen.
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