1. Liver Physiology
By:
Dr Asma Jabeen

2. Learning Objectives To describe the functional anatomy of liver
To discuss the functions of liver

3. Introduction
The largest organ
2% of total body
weight

4. The Functional Anatomy Of Liver
Functional unit is liver lobule

5. Liver Lobule 0.8 to 2 millimeters in diameter.
Cylindrical structure
0.8 to 2 millimeters in diameter.
50,000 to 100,000 individual lobules in human liver.
Constructed around a central vein that empties into the hepatic veins and then into the vena cava.

7. Liver Lobule

8. Liver Lobule

9. Veins of hepatic lobule
Portal vein from GIT
Portal venules
Hepatic sinusoids
Central vein

10. Arterial supply Hepatic arterioles in the interlobular septa.
Supply arterial blood to septal tissues
Most of these empty directly into the hepatic sinusoids

11. Liver Lobule

12. Liver Sinusoids Extremely porous endothelial lining
Pores 1 micrometer in diameter.
Beneath this lining, lying between the endothelial cells and the hepatic cells, there are narrow tissue spaces called the spaces of Disse.

13. Spaces of Disse Perisinusoidal spaces.
The millions of spaces of Disse connect with lymphatic vessels in the interlobular septa.

14. Blood Flow In Liver
About 1050 milliliters of blood flows from the portal vein into the liver sinusoids each minute,
Additional 300 milliliters flows into the sinusoids from the hepatic artery,
The total averaging about 1350 ml/min.
This amounts to 27 per cent of the resting cardiac output.

15. Functions of liver

16. Formation and secretion of bile Bile acids, bile pigments dissolved in
alkaline electrolyte solution
500 ml/day
Digestion and absorption of fats
Major excretory route for lipid soluble
waste products

17. 2. Nutrient and Vitamin Metabolism
Carbohydrate Metabolism
Storage of large amount of glycogen
Conversion of galactose and fructose to
glucose
Gluconeogenesis
Glucose buffer function of liver

18. Fat Metabolism
Oxidation of fatty acids to supply energy for other body functions
Synthesis of large quantities of cholesterol, phospholipids, and most lipoproteins
Synthesis of fat from proteins and carbohydrates

19. Protein Metabolism Deamination of amino acids
Formation of urea for removal of ammonia from the body fluids
Formation of plasma proteins
Interconversions of the various amino acids and synthesis of other compounds from amino acids

20. 3. Inactivation of various substances:
Hormones:
Several hormones either chemically altered or excreted by the liver like:
Thyroxin
Essentially all the steroid hormones
Liver damage cause overactivity of these hormonal systems

21. Mineral Metabolism
One of the major routes for excreting calcium from the body is secretion by the liver into the bile, which then passes into the gut and is lost in the feces.

22. Drug Inactivation
The active chemical medium of the liver is well known for its ability to detoxify or excrete into the bile many drugs, including
sulfonamides
penicillin
ampicillin
erythromycin.

23. 4. Storage Functions:
The vitamin stored in greatest quantity in the liver is vitamin A
Sufficient quantities of following vitamins can be stored to prevent their deficiency
Vitamin A for as long as 10 months.
vitamin D for 3 to 4 months,
vitamin B12 for at least 1 year

24. Iron Storage Greatest proportion of iron stored in liver
Apoferritin combines reversibly with iron to
form ferritin
If low iron in circulating fluids, released
from ferritin
Blood iron buffer

25. 5. Synthesis of plasma proteins:
Clotting factors
Steroid binding and other hormone
binding proteins

26. 6. Blood cleansing function
Large phagocytic macrophages Kupffer cells
lining the hepatic sinusoids cleanse blood
as it passes through sinusoids.
Less than 0.1 % of bacteria in portal blood
enters systemic circulation

27. Thank you

28. Fate of RBC –
Billirubin
formation and
excretion

30. Jaundice
Jaundice refers to a yellowish tint to the body
tissues, including a yellowness of the skin and deep tissues.
Cause:
Large quantities of bilirubin in ECF either conjugated
or unconjugated.
normal bilirubin: 0.5 mg/dl

33. Diagnostic differences between different types of Jaundice
Van den Bergh reaction:
The lab test that is used to differentiate between
conjugated and unconjugated bilirubin
Direct Van den Berg reaction : Conjugated bilirubin
Indirect Van Den Berg reaction: Unconjugated billirubin

34. In Hemolytic Jaundice: All the bilirubin is in
Unconjugated form
In Obstructive jaundice:
Billirubin is mostly conjugated
Tests for urobilinogen in urine are negative
Clay coloured stools because of absence of
stercobilin & other bile pigments
Significant quantities of conjugated bilirubin
appear in urine

35. Liver Cirrhosis When liver parenchymal cells are destroyed,
they are replaced by
fibrous tissues that
eventually contracts
around blood vessels
greatly impeding flow of portal
blood through the liver.
This disease process is called cirrhosis of liver

36. Causes of liver cirrhosis:
Chronic alcoholism
Excess fat accumulation & inflammation in liver
(Non alcoholic steatohepatitis-NASH)
Ingestion of poisons(carbon tetrachloride)
Infectious hepatitis
Obstruction or infection of the bile ducts

37. Portal Hypertension & Ascites
1. Impedance in portal circulation due to clot etc-
portal hypertension
2. Rise of capillary pressure to 15 to 20 mmHg
above normal,
edema of gut wall and
transudation of fluid
from gut serosa- Ascites
3. Increased pressure
in hepatic vein-
large amount of
transudate into lymph-
“sweating” from
the surface of liver-Ascites

39. Thank You