Liver is Intraperitoneal organ (enveloped by visceral peritoneum). It is both an endocrine gland and an exocrine gland. Liver is largest and heaviest gland in the body. Liver appearance is a dark reddish-brown organ.
Weigh - Around 1 to 2.3 kg
Location of Liver
Liver situated upper part of abdominal cavity. Occupying greater part of right hypochondriac region and extending into left hypochondriac region. It is tucked against the inferior surface of diaphragm.
Organ Associated with Liver
Superiorly and Anteriorly; Diaphragm and Anterior abdominal wall.
Inferiorly; Stomach, Bile duct, Duodenum, Right kidney, Hepatic flexure of colon
Posteriorly; Oesophagus, Gall bladder, Inferior venacava, Vertebral column and Diaphragm
Laterally; Lower ribs and Diaphragm
Structure of Liver
Liver reddish and wedge shaped organ.
Located under diaphragm
It's upper and anterior surfaces are smooth and curved to fit under surface of diaphragm
It's posterior surface irregular in outline
Liver is enclosed by visceral peritoneum
Glisson's Capsule
Liver is covered by dense irregular connective tissue that lies beneath peritoneum called Glisson's capsule.
Glission capsule is layer of connective tissue surrounding the liver and ensheathing (enclose in cover hepatic artery, portal vein, bile duct with in liver.
Porta Hepatis or Hilum of Liver/ Transverse Fissure of Liver
Porta hepatis centrally placed groove which anatomically separates caudate and quadrate lobes. The porta hepatis is a deep fissure in the inferior surface or visceral surface of liver. The porta hepatis on the visceral surface of the right lobe of liver is where major vessels, ducts and nerve enter or leave the liver (except hepatic veins). It situated between caudate lobe posteriorly and quadrate lobe anteriorly.
Enter porta hepatis - Portal vein, hepatic artery, hepatic plexus of nerve.
Leave porta hepatis - Right and left hepatic duct, lymphatic vessel.
Porta hepatitis separates the quadrate lobe in front from the caudate lobe. It lies between caudate lobe (above) and quadrate lobe (below).
The gallbladder lies in a shallow fossa placed on the visceral surface of right lobe of Liver.
Porta hepatis also transmits nerves and lymphatics-
1. Sympathetic nerves - It provide afferent pain impulses from the liver and gall bladder to the brain.
2. Hepatic branch of the vagus nerve (Cranial nerve; X).
Lobes of Liver
Liver is divided in two lobe -
1. Right lobe
2. Left lobe
Falciform ligament is lie on front of the live that makes division of right and left lobes of liver. Free border of the falciform ligament is the ligamentum teres (round ligament).
1. Right Lobe
Right lobe of Liver is 6 times larger than the left lobe. Right lobe situated over the right kidney and right colic (hepatic) flexure of the large intestine.
Right lobe has-
1. Caudate lobe (above)
2. Quadrate lobe (below)
A.Caudate lobe
Quadrate lobe is situated on the posterior surface of liver on right lobe. It is located right side of inferior venacava.
It supplied by left and right hepatic artery and portal vein. Blood from caudate lobe drain directly into inferior venacava.
B. Quadrate lobe
Quadrate lobe is located on the inferior surface or visceral surface of the liver on right side.
It is located right side of gall bladder, ligamentum teres on the left and posteriorly by porta hepatis.
2. Left Lobe
Left lobe of liver is much smaller than the right lobe. It forms only 1/6th of liver. It lies over the stomach.
Microscopic Anatomy of Liver
Microscopic Anatomy of Liver
Lobes of Liver made up of many functional units called lobules.
Lobules are hexagonal outline formed by cubical shaped cell called Hepatocytes. Liver is covered by connective tissue capsule called Glisson's capsule that covers surface of the liver.
At porta hepatis, connective tissue capsule send branching network of septa (walls) into the liver. Connective tissue septa divided the liver into lobules with portal triad at each corner.
Portal Triad
Portal triad commonly located portal vein, hepatic artery, hepatic duct .
Each corner of lobule contains portal area or portal triad. It composed of branches of portal vein, hepatic artery, bile duct and nerve.
Hepatic Lobules
Hepatic lobules have central vein at the center of each lobule.
Liver cells or hepatic cells with in lobules are arranged in one thick plate like layers or columns called hepatic cord. It composed of hepatocytes.
Hepatic cords radiate out from central vein of each lobule like spokes of wheel. Between radiating rows of cells are blood channels called Sinusoids, which transport blood from branches of portal vein and hepatic artery.
Blood flows from the artery and vein in portal areas into sinusoid. Then to central vein, which drain it from the lobule into the hepatic vein.
Wall of sinusoids lined with endothelial cells and attached to Kuffer's cells that engulf and digest wormout red and white blood cells, microorganism and foreign particles passing through the liver.
Blood Supply of Liver
Function of Liver
Function of Liver
1. Protein metabolism
2. Carbohydrate metabolism
3. Fat metabolism
4. Removal of drugs (detoxification)
5. Production of heat
6. Maintenance of body temperature (keep stable)
7. Secretion of bile (include bile salts, bile pigments, cholesterol, excretion of conjugate bilirubin) and prevent jaundice
8. Phagocytosis; hepatic phagocytic (kuffer's cell) of liver engulf bacteria and debris that enter the liver.
9. Synthesis- synthesis of vitamin A, synthesis of vitamin D forming fetal erythrocytes.
10. Storage center (Vitamin A, D, E, K); Store fat soluble vitamin, store glucose in form Glycogen.
Stores fats and amino acid that converted in glucose.
Metabolic Function of Liver
1. Protein metabolism
A. Liver deaminates amino acid
Liver removes nitrogenous portion from amino acid. Nitrogenous portion converted into urea which is excereted in urine.
B. Liver breakdown nucleoprotein to form uric acid, which is excreted in urine.
C. Transmination
Remove nitrogenous portion of amino acid, attach it for formation of new amino acid.
D. Synthesis of plasma protein and most blood clotting factors from amino acids.
2. Carbohydrates metabolism
Liver important in maintaining normal blood glucose level.
A. Glycogenesis (conversion of glucose) - in form of glycogen, when blood glucose level is high (in presence of insulin).
B. Glycogenolysis (breakdown of glycogen) - convert in glucose , when blood glucose level is low (In presence of glucagon).
C. Gluconeogenesis; liver convert certain amino acids and lactic acid to glucose when blood glucose level is too low.
D. Liver convert galactose and fructose to glucose.
3. Fat metabolism
1. Liver stores some triglycerides (neutral fats).
2. Liver breakdown fatty acids into acetylcoenzyme A.
3. It convert excess Acetyl coenzyme A into Ketone bodies (ketogenesis).
4. Hepatic cells synthesize cholesterol and use cholesterol to make bile salts.
5. Liver important role is formation of phospholipids.
4. Detoxification (Removal of drugs)
1. Liver can detoxify or excrete into bile, drug such as- Penicillin, Erythromycin, Sulfonamides.
2. Detoxification of poisons and toxins produce by microbes occurs in liver.
3. Liver can chemically alter or excrete thyroid hormone and steroid hormones such as Estrogen, Aldosterone.
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