Hepatobilliary system

Hepatobilliary System
BMS 1.2
KIU, WESTERN CAMPUS.

INTRODUCTION
• In the upper right quadrant of the abdominal cavity
is a large red-mass that look like a sleeping giant.
• It doesn't pulsate, it doesn't move much rather
only passively, and you don't ordinarily see it
secreting anything. This soft, almost jelly-like mass
is the liver.
• Without it, the body is kaput. Fortunately, a body
can survive on about 1/3 the amount of liver that
the normal person has.
What this brooding shapeless hulk of red does is a
subject of our discussion.
11/26/2015 2

Structure and Function of the Liver
The liver is essential for life, yet it can suffer extensive damage
before malfunction becomes pronounced. Although functionally
complex, histologically, the liver is nothing more than a greatly
modified tubular gland.
The liver is divided) into four lobes: the right (the largest lobe),
left, quadrate and caudate lobes.
Supplied with blood via the portal vein and hepatic artery.
Blood carried away by the hepatic vein.
It is connected to the diaphragm and abdominal walls by five
ligaments.
Gall Bladder
Muscular bag for the storage, concentration, acidification and
delivery of bile to small intestine11/26/2015 3

Location of the Liver
• The liver is the largest
visceral organ in the body
and is primarily in the
right hypochondrium and
epigastric region,
extending into the left
hypochondrium and
further protected by the
costal cartilages.
• It is, for the most part,
covered by peritoneum
and entirely by
connective tissue. The
upper surface of the
organ fits nicely against
the inferior surface of the
diaphragm.
11/26/2015 4

Surfaces
 Diaphragmatic surface in the
anterior, superior, and
posterior directions;
 Visceral surface in the
inferior direction
• There are, on the surface, 4
lobes: right, left, caudate and
quadrate.
• The Falciform ligament divides
the liver into two main lobes,
right and left, with the right
lobe being the larger and is
sub- divided into the right lobe
proper, the caudate lobe and
the quadrate lobe.
11/26/2015 5

Diaphragmatic surface
Is smooth and domed, lies against
the inferior surface of the
diaphragm. Associated with it are
the subphrenic and hepatorenal
recesses.
• Subphrenic recess separates the
diaphragmatic surface of the liver
from the diaphragm and is
divided
into right and left areas by the
falciform ligament, a structure
derived from the ventral mesentery
in the embryo;
• Hepatorenal recess is a part of
the peritoneal cavity on the right
side between the liver and the
right kidney and right suprarenal
gland.
11/26/2015 6

Visceral surface
Is covered with visceral peritoneum
except in the fossa for the
gallbladder and at the porta hepatis,
and structures related to it include:
• the right anterior part of the
stomach;
• the superior part of the duodenum;
• the lesser omentum;
• the gallbladder;
• the right colic flexure;
• the right transverse colon;
• the right kidney;
• the right suprarenal gland.
Porta hepatis serves as the point of
entry into the liver for the hepatic
arteries and the portal vein, and the
exit point for the hepatic ducts
11/26/2015 7

Associated ligaments
• The liver is attached to the AAW by
the falciform ligament and, except for
a small area against the diaphragm
(the bare area),
• the liver is almost completely
surrounded by visceral peritoneum.
Additional folds of peritoneum
connect the liver to the stomach
(hepatogastric ligament), the
duodenum (hepatoduodenal
ligament), and the diaphragm (right
and left triangular ligaments and
anterior and posterior coronary
ligaments).
The bare area is a part of the liver on the
diaphragmatic surface where there is no
intervening peritoneum between the
liver and the diaphragm:
• anterior boundary of the bare area is
indicated by a reflection of
peritoneum-the anterior coronary
ligament;
• posterior boundary of the bare area is
indicated by a reflection of
peritoneum-the posterior coronary
ligament;
• where the coronary ligaments come
together laterally, they form the right
and left triangular ligaments
11/26/2015 8

LOBES
Liver is divided into right and left lobes by
fossae for the gallbladder and the IVC.
The right lobe is the largest lobe,
whereas the left lobe of liver is smaller.
The quadrate and caudate lobes are
described as arising from the right lobe of
liver, but functionally are distinct:
• Quadrate lobe is visible on the upper
part of the visceral surface of the liver
and is bounded on the left by the
fissure for ligamentum teres and on
the right by the fossa for the
gallbladder. Functionally it is related
to the left lobe of the lever.
• Caudate lobe is visible on the lower
part of the visceral surface of the liver
and is bounded on the left by the
fissure for the ligamentum venosum
and on the right by the groove for the
IVC. Functionally, it is separate from
the right and the left lobes of the liver.
11/26/2015 9

GALLBLADDER
The gallbladder is a pear-shaped sac
lying on the visceral surface of the
right lobe of the liver in a fossa
between the right and quadrate
lobes. It has:
• a rounded end (fundus of
gallbladder), which may project
from the inferior border of the
liver,
• a major part in the fossa (body of
gallbladder), which may be
against the transverse colon and
the superior part of the
duodenum;
• a narrow part (neck of
gallbladder) with mucosal folds
forming the spiral fold
The gallbladder receives,
concentrates, and stores bile from
the liver.
11/26/2015 11

Microscopic Anatomy
• Hepatocyte—functional
unit of the liver
– Cuboidal cells
– Arranged in plates
lobules
– Nutrient storage and
release
– Bile production and
secretion
– Plasma protein synthesis
– Cholesterol Synthesis
11/26/2015 12

Microscopic Anatomy
• Kuppfer cells
– Phagocytic cells
• Fat Storing Cells
• Sinusoids
– Fenestrated vessel
– Wider than capillaries
– Lined with
endothelial cells
– Blood flow
• Branches of the
hepatic artery
• Branches of the
Hepatic portal vein,
central vein
• Bile canaliculi
11/26/2015 13

Functions
• The liver has more than 200 functions, including:
– Storage of Nutrients
– Breakdown of erythrocytes
– Bile Secretion
– Synthesis of plasma Proteins
– Synthesis of cholesterol
Storage of Nutrients
Hepatocytes absorb and store excess nutrients in the blood
Glucose (glycogen)
Iron
Retinol (Vitamin A)
Calciferol (Vitamin D)
Nutrients released when levels are too low
11/26/2015 14

Bile Secretion
Bile Contents
HCO3
- (Bicarbonate)
Bile salts
Bile pigment
Cholesterol
Stored in gall bladder
Concentrated
acidified
Discharged into small intestine
via bile duct
Breakdown of Erythrocytes
• RBC’s have a life span of 120 days.
• RBC’s weaken and rupture,
releasing hemoglobin into the
blood plasma.
• Hemoglobin is absorbed by
phagocytosis by Kuppfer cells in
the liver.
• Hemoglobin is split into:
 Heme groups
 Iron is removed from heme leaving
a substance called bilirubin (bile
pigment).
• Iron is carried to bone marrow
where it is used to produce new
hemoglobin for RBC’s
• Bilirubin becomes a component of
bile.
 Globins
Hydrolysed to amino acids and
returned to the blood
11/26/2015 15

Synthesis of Cholesterol
• Produced by hepatocytes
• Some used for bile production
• Some transported for use in the rest
of the body
– Synthesis and repair of cell
membranes or stored in the liver.
– Precursor by testis, ovaries or the
adrenal gland to make steroid
hormones.
• progestins
• glucocortoids
• androgens
• estrogens
• mineralocortoids
– It is also a precursor to vitamin D.
11/26/2015 16

Blood supplyBlood enters the liver from two sources,
• Hepatic portal vein (do not confuse with
hepatic vein) and
• Hepatic artery.
The hepatic portal vein is the venous drainage
for the large and small intestine, the stomach
and terminal esophagus and the spleen. Since
the function of the spleen is to filter out worn
out and broken down RBC’s, the splenic vein
of the hepatic portal system carries the
products of red cell breakdown to the liver.
The mesenteric veins carry deoxygenated
blood and the products of intestinal digestion
and absorption (amino acids, mono and
disaccharides and short chain fatty acids; long
chain fatty acids are absorbed via the
lymphatic system).
Outside the liver these veins come together to
form the hepatic portal vein.
About 60% of the blood perfusing the liver is
from the hepatic portal vein. Entering the liver
next to the hepatic portal vein is the hepatic
artery. This supplies about 40% of the
perfusing blood.
11/26/2015 17

Portal Circulation
• These two vessels remain separate in their passage through
the liver until they reach the lobule.
• At each corner of the hexagonal liver lobule is a group of
three structures: a branch of the hepatic portal vein, a branch
of the hepatic artery, and a bile duct. These three structures
comprise the portal triad.
• As the two blood vessels leave the portal triad, they empty
into the sinusoids (large endothelial lined space) and in it the
blood from the two sources begins to mix.
• It percolates through the sinusoids toward the center of the
lobule where the central vein is located. It passes through a
series of veins that collect from many lobules to enter the
right and left hepatic veins which empty into the IVC.
• Recall the closeness of the opening of the hepatic-veins to
the termination of the IVC in the right atrium.
11/26/2015 19

Portal Circulation
Some further comments are now in order:
l. Portal venules receive blood via the portal veins. These
venules empty into either liver sinusoids (located between the
cell plates) or into the central vein.
2. Hepatic arterioles are also seen within the interlobular
septae. These arterioles provide arterial blood to the septal
tissues and may empty into the sinusoids.
3. The venous sinusoids are lined with two different cell types:
• Endothelial cells - have large pores, allows H2O and plasma
proteins to pass freely.
• Kuppfer cells - reticuloendothelial cells capable of
phagocytizing bacteria and other foreign matter in the blood.
4. The average rate of blood flow through the liver is 1,400
ml/min.
11/26/2015 20

Venous drainage
• The IVC receives blood
from the liver via a series
of hepatic veins which
drain the central vein. The
hepatic vein series can be
enumerated as follows:
1. left hepatic v. - drains left
lobe
2. middle hepatic v. - drains
central portion and may join
the left branch to form a
common trunk
3. right hepatic v. - drains
most of the right lobe.
11/26/2015 21

Portosystemic anastomosis
In normal individuals, 100% of the portal
venous blood flow can be recovered from
the hepatic veins, whereas in patients with
elevated portal vein pressure (e.g. due to
cirrhosis), there is significantly less blood
flow to the liver.
The rest of the blood enters collateral
channels, which drain into the systemic
circulation at specific points. The largest of
these collaterals occur at:
• the gastroesophageal junction around
the cardia of the stomach-where the
left gastric vein and its tributaries form
a portosystemic anastomosis with
tributaries to the azygos system of
veins of the caval system;
• the anus-the superior rectal vein of the
portal system anastomoses with the
middle and inferior rectal veins of the
systemic venous system;
• the AAW around the umbilicus-the
para-umbilical veins anastomose with
veins on the AAW.
hvh
11/26/2015 22

Clinical Correlate
 Gallstones are present in approximately 10% of people over
the age of 40 and are more common in women. They consist
of a variety of components, but are predominantly a mixture
of cholesterol and bile pigment. They may undergo
calcification, which can be demonstrated on plain
radiographs.
• gallstones impact in the region of Hartmann's pouch, which
is a bulbous region of the neck of gallbladder. When the
gallstone lodges in this area, the gallbladder cannot empty
normally and contractions of the gallbladder wall produce
severe pain. If this persists, a cholecystectomy (removal of
gallbladder) may be necessary.
• Sometimes the gallbladder may become inflamed
(cholecystitis). If the inflammation involves the related
parietal peritoneum of the diaphragm, pain may not only
occur in the right upper quadrant of the abdomen, but may
also be referred to the shoulder on the right side (C3-C5).11/26/2015 23

Clinical Correlate
 Jaundice is a yellow discoloration of the skin caused by excess
bile pigment (bilirubin) within the plasma. The yellow colour
is best appreciated by looking at the normally white sclerae of
the eyes, which turn yellow.
• Pre-hepatic jaundice This type of jaundice is usually produced
by conditions where there is an excessive breakdown of red
blood cells (e.g. in incompatible blood transfusion and
hemolytic anemia).
• Hepatic jaundice The complex biochemical reactions for
converting fat-soluble into water-soluble bilirubin may be
affected by inflammatory change within the liver (e.g. due to
hepatitis or chronic liver disease such as liver cirrhosis) and
poisons (e.g. paracetamol overdose).
• Post-hepatic jaundice Any obstruction of the biliary tree can
produce jaundice, but the two most common causes are
gallstones within the bile duct and an obstructing tumor at
the head of the pancreas.
11/26/2015 24

Cirrhosis of the Liver
The term cirrhosis denotes chronic tissue degeneration in which cells
are destroyed leading to the formation of fibrous scar tissue. As the
cellular destruction continues, blood, lymph and bile channels within
the liver become distorted and compressed, leading to intrahepatic
congestion, portal hypertension and impaired liver function. The fibrous
changes within the organ cause it to become firmer and smaller. The
surface, however, becomes rough and bumpy because of the
development of nodules on the surface of the organ. The nodules are
regenerated hepatic cells.
The two types of cirrhosis considered in this objective have the
following distinguishing characteristics:
Laennec's portal cirrhosis
scar tissue surrounds portal area
most commonly due to chronic alcoholism
Biliary
scarring around bile ducts and lobes of liver
rarer than Laennec's cirrhosis11/26/2015 25

It is important to remember that cirrhosis is a chronic
progressive disease and, although it may be halted in some of
its stages, the damage that has already occurred is not
reversible. Cirrhosis is the result of a fibroplasia that leads to
extensive scarring. The etiology is unknown although there is
usually associated with it liver cell changes or destruction is
unable to inactivate estrogens which leads to testicular atrophy
11/26/2015 26

Hepatobilliary system

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