Liver Functions

1. Functions of the Liver
“A healthy liver is a sign of a healthy
body”
Kareem Austin
Group 1
April 11th 2010

2. What is the Liver?
 Dark/Reddish Brown, vital organ.
 Both metabolic and excretory.
 Largest internal organ and largest gland.
 Described as having a double blood supply
 Lies on the right side of the abdominal cavity
beneath the diaphragm.
 In males it weighs from 1.4 to 1.6 kilograms, in
females from 1.2 to 1.4 kilograms
 The Liver is extremely resilient.

3. Liver Structure
 Macroscopic/Gross structure
At the macroscopic level, the liver is divided by fossae (fissures) on its
surface into two major lobes, (left and right) and two smaller lobes
(quadrate and caudate).
It is connected to the diaphragm and abdominal walls by five
ligaments: the membranous falciform (also separates the right and left
lobes), coronary, right and left triangular ligaments, and the fibrous
round ligament (derived from the embryonic umbilical vein).

4. Liver Structure cont’d
 Microscopic structure
At the microscopic level, the liver consists of hexagonal shaped functional units
called hepatic lobules. These consist mostly of hepatocytes (the most common type
of liver cell) arranged in thin layers that radiate from the central canal (central vein)
to the periphery of the lobule. Between the radiating rows of hepatocytes are small
blood vessels called sinusoids. These receive oxygen-rich blood from the hepatic
artery and nutrients from the intestines via the portal vein. The oxygen and nutrients
diffuse through the capillary walls into the liver cells.
Within the sinusoids are specialized macrophages called Kupffer cells that figure
prominently in the recycling of old red blood cells.
At the corners of each lobule is a complex, called the portal area, composed of
branches of the hepatic portal vein, hepatic artery, bile duct and nerve. Bile drains
from the hepatocytes by the many small bile ducts that unite to form the main bile
duct of the liver, the hepatic duct. This joins the cystic duct, which leads from the
gallbladder, to form the common bile duct, which drains into the duodenum.
The central canal is a blood vessel in the middle of each lobule which receives blood
from the hepatic portal vein and hepatic artery via the sinusoids and drains the blood
into the hepatic vein.

6. Liver Structure

7. Functional Units of Liver
 Lobules which are made up of hepatocytes
 Hepatocytes make up 70-80% of the liver’s mass
 Surrounded be interlobular veins (branches of hepatic vein
that empty into the vena cava)
 Interlobular arterial branches (proper hepatic artery)
 Bile ductus- series of ducts form the common
hepatic duct
 Bile canaliculi
 Canals of Hering
 Interlobular bile ducts
 Intrahepatic bile ducts
 left and right hepatic ducts

8. Hepatocytes

9. Functions of the Liver
 Metabolic
 Storage
 Excretory/Secretory
 Protective
 Circulatory
 Coagulation

10. Metabolic Functions
 Carbohydrate metabolism
 Gluconeogenesis (the synthesis of glucose from certain amino
acids, lactate or glycerol )
 Glycogenolysis and glycogenesis (breakdown of glycogen to
glucose/ formation of glycogen from glucose)
 Hormone metabolism
 Synthesis of fatty acids, lipoproteins,cholesterol
 Ketogenesis (breakdown of keytones to fats)
 Protein Metabolism
 Synthesis of plasma proteins (albumin, globulin, fibrinogen)
 Urea synthesis (ammonia to urea)
 Red blood cell production (In the first trimester of the fetus)

11. Storage Functions
 Glycogen
 Vitamins A, D, E, K (fat soluable)
B12 (water soluable)
 Iron
 Copper

12. Excretory/Secretory
 Bile
– Water
– Cholesterol
– Bile pigments (Bilirubin and Biliverdin)
– Anions of the Bile acids
– Phospholipids (mainly lecithin)
– Bicarbonate and other ions
 Insulin-like Growth Factor 1(IGF-1)
 Most blood proteins (save antibodies) are synthesis and
therefore secreted by the liver
 Cholesterol, fatty acids (via lipoproteins)

13. Protective Function
 Purification, Transformation, and Clearance -
The liver removes harmful substances (such as
ammonia and toxins) from the blood and then breaks
them down or transforms them into less harmful
compounds. In addition, the liver metabolizes most
hormones and ingested drugs to either more or less
active products.
 Kupffer cells - ingest bacteria or other foreign
material from the blood

14. Circulatory Function
 While the liver is technically part of the
gastrointestinal system, it also plays an important
role in blood circulation. The liver has been called
the "antechamber of the heart" because it collects
and processes all of the gastrointestinal blood
through the portal vein and delivers it to the right
side of the heart. The liver receives blood through
two vascular systems, the portal vein and hepatic
artery.

16. Coagulator Functions
 Production and secretion of coagulation
factors
 fibrinogen I
 prothrombin II
 Factors (V, VII, IX, X, XI)
 protein C
 protein S
 antithrombin.

17. Liver Enzymes
 Transaminases
– aspartate aminotransferase (AST or SGOT)
– alanine aminotransferase (ALT or SGPT)
 Cholestatic Enzymes
– alkaline phosphatase (AP)
– gamma-glutamyl transferase (GGT)

18. Liver Enzymes cont’d
 Liver enzymes are proteins that help to
speed up a chemical reaction in the liver.
Liver function tests are blood tests that are
used to evaluate various functions of the liver
– for example, metabolism, storage, filtration
and excretion, which are often performed by
liver enzymes. However, not all liver function
tests are measures of enzyme function

19. Pathology
A common sign of a damaged liver is jaundice, a yellowness of the eyes and
skin. This happens when bilirubin, a yellow breakdown product of red blood
cells, builds up in the blood. Among the many diseases of the liver are:
 Hepatitis (inflammation of the liver), caused mainly by various
viruses but also by some poisons, autoimmunity, or hereditary
conditions.
 Cirrhosis is the formation of fibrous tissue in the liver, replacing
dead liver cells. The death of the liver cells can for example be
caused by viral hepatitis, alcoholism or contact with other liver-
toxic chemicals.
 Hemochromatosis, a hereditary disease causing the
accumulation of iron in the body, eventually leading to liver
damage.

20. Pathology cont’d
 Cancer of the liver (primary hepatocellular carcinoma or
cholangiocarcinoma and metastatic cancers, usually from other
parts of the gastrointestinal tract).
 Wilson's disease, a hereditary disease which causes the body
to retain copper.
 Primary sclerosing cholangitis, an inflammatory disease of
the bile duct, autoimmune in nature.
 Primary biliary cirrhosis, autoimmune disease of small bile
ducts
 Budd-Chiari syndrome, obstruction of the hepatic vein.
 Gilbert's syndrome, a genetic disorder of bilirubin metabolism,
found in about 5% of the population

22. Summary
 The liver is the largest internal organ in the human
body
 The liver is extremely vital for our survival providing
numerous functions.
– Metabolising and detoxifying toxic material
– Storage of vitamins, minerals and sugars
– Synthesis and secretion of essential proteins and lipids
– Production and secretion of bile
 A healthy liver is a sign of a healthy organism. 

23. Questions?

24. Thank you for your
attention!