Liver Function 1

8/12/2019 Liver Function 1

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http://www.toons4biz.com/Cartoon-Liver-Pointing-Up-p/liver_cartoon_liver01x005.htm


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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
http://www.usc.edu/hsc/dental/ghisto/gi/c_90.htmlhttp://www.usc.edu/hsc/dental/ghisto/gi/c_90.htmlhttp://www.usc.edu/hsc/dental/ghisto/gi/c_90.html


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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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Liver Function 1

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