Download - Liver Function 1
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Liver- Position
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Liver Introduction
Also calledhepar
Largest glandin the body
Weighs about 1600 gm in males,1300 gm
in females
Occupies the right hypochondrium,
epigastrium & left hypochondrium
Most part of the liver is covered by ribs &
costal cartilages
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External Features
Wedge shaped, resembles four sided
pyramid.
3 surfaces- Superior, posterior & inferior.
Inferior surfaceis well defined -also
called visceral surface
Inferior borderis well defined & the otherborders are rounded
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External featuresEx
Superior surfaceis attached to the
diaphragm and anterior abdominal wall by
falciform ligament and the free margin
contains ligamentum teres (obli terated
umbi l ical vein).
Inferior and posterior surfacesare divided
into four lobes namely right lobe, left lobe,
quadrate lobe & caudate lobe.
External Features
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Lobes of Liver
Liver is divided into right & left lobesby
falciform ligament ,fissure for
ligamentum teres & fissure for
ligamentum venosum.
Right lobe is larger than left and has
caudate & quadrate lobes.
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Lobes of Liver
Left lobe
Caudate lobe
Right lobe
Quadrate lobe
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Porta Hepatis
Portahepatis,is the hilum
of the liver transmitting thehepatic ducts, hepatic
artery and portal vein in
that order from before
backwards.
Lesser omentumextends
between porta hepatis and
the lesser curvature of
stomach.
Porta hepatis
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Lobes of Liver
Liver is divided into right & left lobesby
falciform ligament ,fissure for
ligamentum teres & fissure for
ligamentum venosum.
Right lobe is larger than left and has
caudate & quadrate lobes.
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Lobes of Liver
Left lobe
Caudate lobe
Right lobe
Quadrate lobe
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Porta Hepatis
Portahepatis, is the hilum
of the liver transmitting thehepatic ducts, hepatic artery
and portal vein in that order
from before backwards.
Lesser omentumextendsbetween porta hepatis and
the lesser curvature of
stomach.
Porta hepatis
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Biliary Apparatus
Gall bladder.
Cystic duct.
Right and left hepatic ductswhich unite to form
common hepatic duct.Bile duct formed by the union of cystic duct
and common hepatic duct.
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DUCT SYSTEMBile secreted by
liver carried to the
gall-bladder by the
cystic duct orpoured directly
into the duodenum
by the common
bile duct to aid
digestion
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Functional Unit of Liver
Hepatic lobules
Hexagonal structures,
with six portal triads at
the corners of the
lobules and a central
vein in the middle
Connective tissue
capsule (Glissons
capsule) is scanty
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Functional Unit
Each lobule is made of cords of liver cells
(hepatocytes) separated by sinusoids
Cells are arranged in plates which branch
& anastomose
Periphery of each lobule has angular
intervals called portal canals containingbranch of portal vein, hepatic artery &
interlobular bile duct forming a portal triad
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Hexagonal lobules of liver with hepatocytes
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Portal triad
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Cell Types in Liver
C t l i I th
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Central vein: In the
center of the lobule.
Receives blood from
the sinusoids. Kupffer cells:
Reticuloendothelial
cells in the walls of the
sinusoids of the liverThe Kupffer cells are
phagocytic cells which
destroy worn- out wbc,
rbc , bacteria &foreign matte
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Central vein
Kupffer cells:
P th f bil ithi th li
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Pathway of bile within the liver
Bile originates as secretions from the hepatocytes, whichcollect in channels called
Bile canaliculi (tiny passages contained within each cord.)
Canal of Hering, bile ductules at the periphery of classicliver lobules
Bile duct- located in the portal areas
CoH: Canal of Hering.
F ti l U it f Li
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Functional Units of Liver
Classic Lobule
Portal LobuleHepatic Acini (Rappaport)
- a direct correlation between
blood supply and metabolism
Classic Lobule
Model- Anatomical
Hexagonal in shape withthe portal triads.at the
periphery and central vein
at the centre.
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Portal lobules
Triangular in shape, centered around the portal triad
Based on bile flowIn this concept of liver lobulation, the bile duct is in the
centre of the lobule
Bile duct
H ti i ( f R t)
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Hepatic acinus (of Rappaport)
Based on blood flow
The smallest functional unit of the liver, a mass of liverparenchyma that is supplied by terminal branches of the
portal vein and hepatic artery and drained by a terminal
branch of the bile duct (portal triad vessels).
Diamond- shaped region encompassing triangular
sections of two adjacent classic liver lobules with apices
that are the central vein.
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The liver (portal) acinus
provides the bestcorrelation among blood
perfusion, metabolic
activity, and liver pathology.
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G l M t b li F ti
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General Metabolic Functions
Carbohydrate metabo l ism
Maintainence of the blood glucose level:
Glycogenesis(glycogen synthesis), storage
Glygenolysis (glycogen breakdown)
Gluconeogenesis
G l M t b li F ti
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General Metabolic Functions
Protein Metabo l ism
Synthesis of most palsma proteins such
as albumin & transport proteins
Deamiation of amino acids & formation of
urea
G l M t b li F ti
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General Metabolic Function
Lip id metabo l ism
Oxidation of fatty acid to ketone bodies
Synthesis of cholesterol & cholesterolesters
Synthesis of
lipoproteins,triglycerides,phospholipids
synthesis of bile acids
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Cholesterol metabolism
1. Synthesizes cholesterol and releases it
into the blood
2. Secretes plasma cholesterol into the
bile
3. Converts plasma cholesterol into bilesalts
Synthetic Functions
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Synthetic Functions
Hepatocy tes synthesize:
plasma proteinsexcept immunoglobulins
most coagulation factorssuch as fibrinogen
& factorII,V,VII,IX,X XI, XII)
Cholesteterol , lipoproteins (VLDL,HDL)
primary bile acids
St f Vit i
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Storage of Vitamins
Hydroxylation of calciols to calcidiols,
splitting of carotene to retinol
The liver represent a store of lipophilic
vitamins and cobalamin (B12)
Detoxification and Excretion
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Detoxification and Excretion
Subs tances that are inact ivated & exc reted by
the liver inc lude:
Bilirubin
Bile acids
Steroid hormones
Many drugs
Toxins
T f ti f h
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Transformation of hormones
inactivation of steroid hormones
hydrogenation, conjugation
inactivation of insulin and glucagon
inactivation of catecholamines and
iodothyronines - conjugation
dehydrogenation of cholesterol to 7-
dehydrocholesterol and 25-hydroxylation of calciols play an essential role
in calcium homeostasis
M t b li f bili bi
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Metabolism of bilirubin
Bilirubin is potentially toxic catabolic
product of heme metabolism.
When Hb degraded- polypetides are
degraded to aminoacids while the hemegroup are freed of their iron- salvaged
and converted to bilirubin.
M t b li f bili bi
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Metabolism of bilirubin
Approximately 300-400 mg of heme are
degraded in the human body/day
F ti & E ti f bili bi
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Formation & Excretion of bilirubin
Aged & Damaged
RBCs
Haemoglobin
HaemGlobin
UnconjucatedBilirubinn(UB)
Albumin.UBBLOOD
RETICULOENDOTHELIAL
SYSTEM
BLOOD Albumin.UB
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LIVER
LIVER CELL UPTAKE by ligandin
Conjugation with Glucuronyl transferase
Bilirubin glucuronide
GUTCommon Bile Duct
Excretion into the bile
bacterial flora
KIDNEY
Conjugated Bilirubin
Faecal UrobilinogenEnterohepatic circulation
UrinaryUrobilinogen
LIVER
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Elevation of serum bilirubin cause
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Elevation of serum bilirubin causejaundice
Hyperbilirubinemia: Increased plasma concentrations of bilirubin
(> 3 mg/dL) occurs when.?
There is an imbalance between its
production and excretion. Either unconjugated bilirubin or conjugated
bilirubin or both are elevated
All types of hyperbilirubinemia lead to thedeposition of bilirubin in the tissues, skinand sclera of the eye which it imparts yellowcolour.
This condition is called jaundice or icterus
Jaundice
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Jaundice
The sclera of the eye is affected early-because of its high content of elastin
for which bilirubin has high affinity.
Types of jaundice:
Prehepatic
Intrahepatic
Post hepatic (obstructive)
Jaundice
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Jaundice
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