CHAPTER 21 Cardiovascular System: Blood Vessels and Circulation

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kidneys, and adrenal glands are the only abdominal organs outsidethe pelvis that drain directly into the inferior vena cava. The internal iliac veins drain the pelvis and join the external iliacveins from the lower limbs to form the common iliac veins, whichunite to form the inferior vena cava. The major abdominal andpelvic veins are listed in table 21.10 and illustrated in figure 21.26;also see figure 21.28.

TABLE 21.10

Veins Draining the Abdomen andPelvis (figures 21.26 and 21.28)

Hepatic Portal System

The hepatic (he-pat′ik; relating to the liver) portal system (figures 21.27 and 21.28; table 21.11) carries blood drained fromcapillaries within most of the abdominal viscera, such as the stomach,intestines, and spleen, to a series of dilated capillaries, called sinu-soids, in the liver. This system delivers nutrients and othersubstances absorbed from the stomach or small intestine to theliver (see chapter 24).The hepatic portal vein, the largest vein of the system, isformed by the union of the superior mesenteric vein, which drainsthe small intestine, and the splenic vein, which drains the spleen.The splenic vein receives blood from the inferior mesenteric vein,

Inferior vena cava

Hepatic veins

Liver

Gallbladder

Cysticvein

Hepaticportal vein

Duodenum

Stomach

Gastric veins

Gastroomental veins

Spleen

Splenic vein withpancreatic branches

Tail of pancreas

Splenic vein

Gastroomental veins

Head of pancreas

Superiormesenteric vein

Inferior mesenteric vein

Descending colon

Ascending colon

Small intestine

Appendix

FIGURE 21.27 Veins of the Hepatic Portal System

The hepatic portal system begins as capillary beds in the stomach, pancreas, spleen, small intestine, and large intestine. The veins of the hepatic portal sys-tem converge on the hepatic portal vein, which carries blood to a series of capillaries (sinusoids) in the liver. Hepatic veins carry blood from capillaries in theliver to the inferior vena cava (also see figure 21.26).