Download Tributaries of the hepatic portal vein

Mr. Klatt
Anatomy & Physiology
Cat Dissection -- Day 10
Name _________________________________ Class ____
Cat Anatomy – Hepatic Veins
The hepatic portal system is a series of veins that carry blood from the capillaries
of the stomach, intestine, spleen, and pancreas to capillaries in the liver. It is part of the
body’s filtration system. Its main function is to deliver de-oxygenated blood to the liver to
be detoxified further before it returns to the heart.
The hepatic portal system is designed to rid the body of toxins, and it cannot
detect those that are designed to help it. Some drugs must be taken under the tongue,
through the skin, or via suppository to avoid entering the hepatic portal system and being
prematurely metabolized in the liver before reaching general circulation.
I. Hepatic Veins
Pin #
Vessel Name
1
hepatic portal vein
2
inferior mesenteric vein
3
splenic vein
4
superior mesenteric vein
Function
II. Using the textbook, list the function of the four veins above.
III. Label and color (in yellow) the four veins (listed above) on the diagram.
III. Group Assessment
Using pins, identify the veins of the hepatic portal system above on your cat. Once your coloring is
complete and all group members know the veins above, bring your cat and this assignment to Mr. Klatt
for testing.
X______________ Signature for identification of hepatic veins.
Cat Anatomy – Hepatic Veins
The hepatic portal system is a series of veins that carry blood from the capillaries
of the stomach, intestine, spleen, and pancreas to capillaries in the liver. It is part
of the body’s filtration system. Its main function is to deliver de-oxygenated blood
to the liver to be detoxified further before it returns to the heart.
The hepatic portal system is designed to rid the body of toxins, and it cannot
detect those that are designed to help it. Some drugs must be taken under the
tongue, through the skin, or via suppository to avoid entering the hepatic portal
system and being prematurely metabolized in the liver before reaching general
circulation.
I. Hepatic Veins
Vessel Name
hepatic portal vein
Function
the main vein that delivers blood to the liver
inferior mesenteric vein
collects blood from the lower part of the large intestine
splenic vein
collects blood form spleen and stomach
superior mesenteric vein
collects blood from the stomach, small intestines, 2/3 of
the large intestine
Hepatic Portal Vein
The hepatic portal vein is formed by the union of the superior mesenteric and splenic veins, behind
the head of the pancreas and in front of the inferior vena cava. It receives blood from the spleen,
pancreas, and the abdominal part of the alimentary canal, except part of the blood from the anal
canal and the lower end of the rectum. The larger veins forming the portal vein have no valves, but
the smaller tributaries do. It is from seven to ten centimeters (three to four inches) in length. It
passes upward and to the right behind the first portion of the duodenum. It then passes between the
layers of the lesser omentum. It is surrounded by branches of the hepatic plexus of the sympathetic
nerves, lymph vessels and glands, and a prolongation, the fibrous capsule. It lies behind the bile and
hepatic ducts and the hepatic artery. The ducts are to the right, the artery to the left, and the vein is
behind and between the artery and the ducts. Like the hepatic artery, it divides at the porta hepatis
of the liver into a right and a left branch. It then enters the lobes at the porta hepatis. The branch
passing to the right lobe of the liver is almost a direct continuation of the portal vein, while the
branch passing to the left lobe diverges at a right angle from the main stem. Owing to the more
direct course of the right branch, infectious material carried from the stomach or intestines to the
liver by the portal vein is more likely to enter the right branch and lead to involvement of the right
lobe. A slight dilatation immediately below the point where it divides into its two branches is called
the sinus of the portal vein. It receives the left gastric, the right gastric, and the cystic veins. The
veins of the portal system are the portal, gastric, splenic, and superior and inferior mesenteric veins.
ANATOMY
Measuring approximately 8 cm (3 inches) in adults,[2] the hepatic portal vein is located in the right
upper quadrant of the abdomen, originating behind the neck of thepancreas.
In most individuals, the hepatic portal vein is formed by the union of the superior mesenteric vein
and the splenic vein. For this reason, the hepatic portal vein is occasionally called the splenicmesenteric confluence.Occasionally, the hepatic portal vein also directly communicates with the
inferior mesenteric vein, although this is highly variable. Other tributaries of the hepatic portal vein
include thecystic and gastric veins.
Immediately before reaching the liver, the portal vein divides into right and left. It ramifies further,
forming smaller venous branches and ultimately portal venules. Each portal venule courses
alongside a hepatic arteriole and the two vessels form the vascular components of the portal triad.
These vessels ultimately empty into the hepatic sinusoids to supply blood to the liver.
Portacaval anastomoses
The portal venous system has several anastomoses with the systemic venous system. In cases of
portal hypertension these anastamoses may become engorged, dilated, or varicosed and
subsequently rupture.Accessory hepatic portal veins are those veins that drain directly into the liver
without joining the hepatic portal vein. These include theparaumbilical veins as well as veins of the
lesser omentum, falciform ligament, and those draining the gallbladder wall.
Relations
The bile duct and the gastro-duodenal artery lie between the portal vein and the first part of the
duodenum, and there it is in front of the vena cava. In the lesser omentum, it is separated from the
vena cava by the opening into the lesser sac; and its anterior relations are the bile duct again and
the hepatic artery. In the porta, its branches are behind the branches of the hepatic artery and the
hepatic ducts.
Origin and course of portal vein:
The portal vein is about 3 inches long and is formed behind the neck of the pancreas by the union of
the superior mesenteric vein and splenic vein. After its origin, it ascends to the right behind the first
part of duodenum to enter the lesser omentum. It then runs upward in front of the opening into the
lesser omentum (epiploic foramen), and reaches the porta hepatis, where it divides into right and left
terminal branches.
Portal vein in the liver:
Immediately before reaching the liver, the hepatic portal vein divides into right and left branches.
Each branch enters the corresponding lobe of the liver, where they divide further into smaller venous
branches leading into the portal venules. Each portal venule courses alongside a hepatic arteriole
and the two vessels form the vascular components of the portal triad. The venules ultimately empty
into the sinusoids of liver, which supply blood to the organ. From the sinusoids, the blood passes
into the hepatic veins, which joint the inferior vena cava.
Tributaries of the portal vein
There are only a few direct tributaries of the portal vein. The splenic and superior mesenteric veins
form it; a pancreatico-duodenal vein joins it behind the duodenum; the right and left gastric veins join
it immediately before it enters the lesser omentum; and the cystic vein from the gall bladder joins its
right branch.
Tributaries of the hepatic portal vein
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Splenic vein
Superior mesenteric vein
Inferior mesenteric vein
Gastric veins
Cystic vein
Branches of the portal vein
The right branch of the portal vein receives the cystic vein, and then sinks into the right lobe of the
liver. The left branch – narrower and longer – runs to the left end of the porta to sink into the left
lobe.
Physiology
The hepatic portal vein and hepatic arteries form the liver's dual blood supply. Approximately 75% of
hepatic blood flow is derived from the hepatic portal vein, while the remainder is from the hepatic
arteries.
Unlike most veins, the hepatic portal vein does not drain into the heart. Rather, it is part of a portal
venous system that delivers venous blood into another capillary system, namely the hepatic
sinusoids of the liver. In carrying venous blood from the gastrointestinal tract to the liver, the hepatic
portal vein accomplishes two tasks; namely, it supplies the liver with metabolic substrates and it
ensures that substances ingested are first processed by the liver before reaching the systemic
circulation. After draining into the liver sinusoids, blood from the liver is drained by the hepatic vein.
Portal hypertension
Increased blood pressure in the portal vein, called portal hypertension, is a major complication of
liver disease, most commonlycirrhosis.Stigmata of portal hypertension include those of chronic liver
disease: ascites, esophageal varices, spider nevi, caput medusae, and palmar erythema.
Pylephlebitis
Pylephlebitis is infection of the hepatic portal vein, usually arising from an infectious intraabdominal
process such as diverticulosis
Hepatic Veins
The hepatic veins are the carriers of deoxygenated blood that comes via the liver, and
then drain it into the inferior vena cava. They are also the carriers of blood that has been
drained from the colon, pancreas, small intestine, and the stomach, and cleaned by the liver.
These veins originate from the core vein of the liver lobule, but they do not have any valve.
These veins can be segregated into the lower group and the upper group veins. The lower
group veins originate from the right lobe, are relatively smaller in size than the upper group
veins, and vary in numbers. The upper group veins, on the other hand, originate from the
backside of the liver, and drain into the left lobe. The deoxygenated blood from these veins into
the inferior vena cava is delivered back to the heart, where the re-oxygenation process of the
blood takes place. In that respect, the liver performs the role of a cleaning organ when the blood
is on its way back to the heart. Any impediment in the outflow of blood from the hepatic veins
may result in a serious condition known as Budd-Chiari syndrome.
The pancreas in the human body releases pancreatic juices that aid in digestion, by
breaking down foods as they pass through the small intestine. The pancreas also produces
hormones, like insulin, which the body needs to function. The Pancreaticoduodenal veins are
veins located in the pancreas. The arteries and veins function as a transportation system in the
human body. The veins carry blood to the heart, while the arteries carry blood from the heart to
other parts of the body. The heat oxygenates the blood, making it healthier and the veins carry
unhealthy blood from the pancreas and nearby areas. The vein is closely related to the inferior
and superior pancreaticoduodenal artery. The arteries carry blood to the pancreas and
duodenum, which is the first part of the small intestine. The superior artery is located both in
front of and behind the pancreas. The Pancreaticoduodenal veins drain into the portal vein,
which transports blood to the liver, from the intestines and stomach, before transporting it to the
heart.
The Hepatic Portal System
The hepatic portal system is a series of veins that carry blood from the capillaries of the stomach,
intestine, spleen, and pancreas to capillaries in the liver. It is part of the body’s filtration system. Its
main function is to deliver de-oxygenated blood to the liver to be detoxified further before it returns to
the heart.
The hepatic portal system consists of:
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Hepatic portal vein: This is the main vein connected to the liver. It forms at the connection of
the inferior and superior mesenteric veins.
Inferior mesenteric vein: This vein takes blood from the colon and rectum and connects with
the portal vein.
Superior mesenteric vein: This drains blood from the small intestine and connects with the
hepatic portal vein.
Gastrosplenic vein: This tributary is formed by the union of the splenic vein from the spleen
and the gastric vein from the stomach. It joins with the mesenteric vein inside the pancreas.
The hepatic portal system is designed to rid the body of toxins, and it cannot detect those that are
designed to help it. Some drugs must be taken under the tongue, through the skin, or via
suppository to avoid entering the hepatic portal system and being prematurely metabolized in the
liver before reaching general circulation.
The Portal System of Veins
The portal system includes all the veins which drain the blood from the abdominal part of the digestive tube (with
the exception of the lower part of the rectum) and from the spleen, pancreas, and gall-bladder. From these viscera
the blood is conveyed to the liver by the portal vein. In the liver this vein ramifies like an artery and ends in capillarylike vessels termed sinusoids, from which the blood is conveyed to the inferior vena cava by the hepatic veins.
From this it will be seen that the blood of the portal system passes through two sets of minute vessels, viz., (a) the
capillaries of the digestive tube, spleen, pancreas, and gall-bladder; and (b) the sinusoids of the liver. In the adult
the portal vein and its tributaries are destitute of valves; in the fetus and for a short time after birth valves can be
demonstrated in the tributaries of the portal vein; as a rule they soon atrophy and disappear, but in some subjects
they persist in a degenerate form.
The portal vein (vena portæ) is about 8 cm. in length, and is formed at the level of the second lumbar vertebra by
the junction of the superior mesenteric and lienal veins, the union of these veins taking place in front of the inferior
vena cava and behind the neck of the pancreas. It passes upward behind the superior part of the duodenum and
then ascends in the right border of the lesser omentum to the right extremity of the porta hepatis, where it divides
into a right and a left branch, which accompany the corresponding branches of the hepatic artery into the substance
of the liver. In the lesser omentum it is placed behind and between the common bile duct and the hepatic artery, the
former lying to the right of the latter. It is surrounded by the hepatic plexus of nerves, and is accompanied by
numerous lymphatic vessels and some lymph glands. The right branch of the portal vein enters the right lobe of the
liver, but before doing so generally receives the cystic vein. The left branch, longer but of smaller caliber than the
right, crosses the left sagittal fossa, gives branches to the caudate lobe, and then enters the left lobe of the liver. As
it crosses the left sagittal fossa it is joined in front by a fibrous cord, the ligamentum teres (obliterated umbilical
vein), and is united to the inferior vena cava by a second fibrous cord, the ligamentum venosum (obliterated ductus
venosus).
Tributaries.—The tributaries of the portal vein are:
Lienal.
Superior Mesenteric.
Coronary.
Pyloric.
Cystic.
Parumbilical.
The Lienal Vein (v. lienalis; splenic vein) commences by five or six large branches which return the blood from the
spleen. These unite to form a single vessel, which passes from left to right, grooving the upper and back part of the
pancreas, below the lineal artery, and ends behind the neck of the pancreas by uniting at a right angle with the
superior mesenteric to form the portal vein. The lienal vein is of large size, but is not tortuous like the artery.
Tributaries.—The lineal vein receives the short gastric veins, the left gastroepiploic vein, the pancreatic veins, and
the inferior mesenteric veins.
The short gastric veins (vv. gastricæ breves), four or five in number, drain the fundus and left part of the greater
curvature of the stomach, and pass between the two layers of the gastrolienal ligament to end in the lienal vein or in
one of its large tributaries.
The left gastroepiploic vein (v. gastroepiploica sinistra) receives branches from the antero-superior and posteroinferior surfaces of the stomach and from the greater omentum; it runs from right to left along the greater curvature
of the stomach and ends in the commencement of the lienal vein.
The pancreatic veins (vv. pancreaticæ) consist of several small vessels which drain the body and tail of the
pancreas, and open into the trunk of the lienal vein.
The inferior mesenteric vein (v. mesenterica inferior) returns blood from the rectum and the sigmoid, and
descending parts of the colon. It begins in the rectum as the superior hemorrhoidal vein, which has its origin in the
hemorrhoidal plexus, and through this plexus communicates with the middle and inferior hemorrhoidal veins. The
superior hemorrhoidal vein leaves the lesser pelvis and crosses the left common iliac vessels with the superior
hemorrhoidal artery, and is continued upward as the inferior mesenteric vein. This vein lies to the left of its artery,
and ascends behind the peritoneum and in front of the left Psoas major; it then passes behind the body of the
pancreas and opens into the lienal vein; sometimes it ends in the angle of union of the lienal and superior
mesenteric veins.
Tributaries.—The inferior mesenteric vein receives the sigmoid veins from the sigmoid colon and iliac colon, and
the left colic vein from the descending colon and left colic flexure.
The Superior Mesenteric Vein (v. mesenterica superior) returns the blood from the small intestine, from the
cecum, and from the ascending and transverse portions of the colon. It begins in the right iliac fossa by the union of
the veins which drain the terminal part of the ileum, the cecum, and vermiform process, and ascends between the
two layers of the mesentery on the right side of the superior mesenteric artery. In its upward course it passes in
front of the right ureter, the inferior vena cava, the inferior part of the duodenum, and the lower portion of the head
of the pancreas. Behind the neck of the pancreas it unites with the lienal vein to form the portal vein.
Tributaries.—Besides the tributaries which correspond with the branches of the superior mesenteric artery, viz., the
intestinal, ileocolic, right colic, and middle colic veins, the superior mesenteric vein is joined by the right
gastroepiploic and pancreaticoduodenal veins.
The right gastroepiploic vein (v. gastroepiploica dextra) receives branches from the greater omentum and from the
lower parts of the antero-superior and posteroinferior surfaces of the stomach; it runs from left to right along the
greater curvature of the stomach between the two layers of the greater omentum.
The pancreaticoduodenal veins (vv. pancreaticoduodenales) accompany their corresponding arteries; the lower
of the two frequently joins the right gastroepiploic vein.
The Coronary Vein (v. coronaria ventriculi; gastric vein) derives tributaries from both surfaces of the stomach; it
runs from right to left along the lesser curvature of the stomach, between the two layers of the lesser omentum, to
the esophageal opening of the stomach, where it receives some esophageal veins. It then turns backward and
passes from left to right behind the omental bursa and ends in the portal vein.
The Pyloric Vein is of small size, and runs from left to right along the pyloric portion of the lesser curvature of the
stomach, between the two layers of the lesser omentum, to end in the portal vein.
The Cystic Vein (v. cystica) drains the blood from the gall-bladder, and, accompanying the cystic duct, usually ends
in the right branch of the portal vein.
Parumbilical Veins (vv. parumbilicales).—In the course of the ligamentum teres of the liver and of the middle
umbilical ligament, small veins (parumbilical) are found which establish an anastomosis between the veins of the
anterior abdominal wall and the portal, hypogastric, and iliac veins. The best marked of these small veins is one
which commences at the umbilicus and runs backward and upward in, or on the surface of, the ligamentum teres
between the layers of the falciform ligament to end in the left portal vein.
Collateral venous circulation to relieve portal obstruction in the liver may be effected by communications between
(a) the gastric veins and the esophageal veins which often project as a varicose bunch into the stomach, emptying
themselves into the hemiazygos vein; (b) the veins of the colon and duodenum and the left renal vein; (c) the
accessory portal system of Sappey, branches of which pass in the round and falciform ligaments (particularly the
latter) to unite with the epigastric and internal mammary veins, and through the diaphragmatic veins with the
azygos; a single large vein, shown to be a parumbilical vein, may pass from the hilus of the liver by the round
ligament to the umbilicus, producing there a bunch of prominent varicose veins known as the caput medusæ; (d)
the veins of Retzius, which connect the intestinal veins with the inferior vena cava and its retroperitoneal branches;
(e) the inferior mesenteric veins, and the hemorrhoidal veins that open into the hypogastrics; (f) very rarely the
ductus venosus remains patent, affording a direct connection between the portal vein and the inferior vena cava.