The Liver and Gall
Bladder
The Liver
• The heaviest gland of the body, weighing about 1.4 kg
• Second largest organ
• Inferior to the diaphragm
• occupies most of the right hypochondriac and part of the
epigastric regions of the abdomino pelvic cavity
Anatomy of
Liver
• Almost completely covered by visceral peritoneum
• Covered by a dense irregular connective tissue layer that
lies deep to the peritoneum
• The liver is divided into two principal lobes
The
Gallbladder
• Pear-shaped sac
• Located in a depression of the posterior surface of the
liver
• Typically hangs from the anterior inferior margin of the
liver
Anatomy of
Gallbladder
The parts of the gallbladder:
• The broad fundus – Projects inferiorly beyond inferior
border of liver
• The body – Central portion
• The neck – Tapered portion
• The body and neck project superiorly
Histology
of Liver
• The lobes are made up of lobules
Lobules contain:
• Hepatocytes (liver cells)
• Sinusoids
• Stellate reticulo endothelial (Kupffer) cells
• Central vein
Hepatic blood flow
Hepatocytes
• Major functional cells of the liver
• Perform a wide array of metabolic & endocrine
functions
• Specialized epithelial cells with 5 to 12 sides
• Make up about 80% of the volume of the liver
The Hepatic Laminae
• Plates of hepatocytes
• Thick bordered by hepatic sinusoids
• Highly branched, irregular structures
• Bile
– A yellow, brownish, or olive-green liquid
– Secreted by hepatocytes
– Serves as both an excretory product and a digestive
secretion
• Bile canaliculi
– Small ducts between hepatocytes
– Collect bile produced by the hepatocytes
– From bile canaliculi, bile passes into bile ductules &
then bile ducts
Hepatic Ducts
Hepatic Sinusoids
• Highly permeable blood capillaries between rows of
hepatocytes
• Receive oxygenated blood from branches of the hepatic
artery
• Nutrient-rich deoxygenated blood from branches of the
hepatic portal vein
• Converge and deliver blood into a central vein
• From central veins, the blood flows into the hepatic veins,
which drain into the inferior vena cava
Portal
Triad
• Together, a bile duct, branch of the hepatic artery, and
branch of the hepatic vein
• Anatomical and functional units
Functions
of Liver
• Carbohydrate
metabolism
– Maintaining a normal blood glucose level
– Convert certain amino acids and lactic acid to glucose
– Liver converts glucose to glycogen and triglycerides for
storage
• Lipid metabolism
– Store some triglycerides
– Break down fatty acids to generate ATP
– Synthesize lipoproteins (Which transport FA, TG and
cholesterol)
– Synthesize cholesterol and use cholesterol to make bile
salts
• Protein metabolism
– Hepatocytes deaminate amino acids used for ATP production
or converted to carbohydrates or fats
– The resulting toxic ammonia converted into the much less
toxic urea, which is excreted in urine
– Synthesize most plasma proteins, such as alpha and beta
globulins, albumin, prothrombin and fibrinogen
• Phagocytosis
– Kupffer cells of the liver phagocytize aged RBC, WBC &
bacteria
• Processing of drugs
and hormones
– Detoxify substances such as alcohol
– Excrete drugs such as penicillin, erythromycin, and
sulfonamides into bile
– Chemically alter or excrete thyroid hormones and steroid
hormones
• Storage
– Prime storage site for certain vitamins (A, D, E, K and
B12) and minerals (iron and copper)
– Released from the liver when needed elsewhere in the body
• Excretion of
bilirubin
– Bilirubin, derived from the heme of aged RBC, absorbed by
the liver from the blood and secreted into bile
– Most of the bilirubin in bile is metabolized in the small
intestine by bacteria and eliminated in feces
• Synthesis of bile
salts
– Bile salts are used in the small intestine for the
emulsification and absorption of lipids
• Activation of
vitamin D
– The skin, liver, and kidneys participate in synthesizing
the active form of vitamin D
Functions
of Gallbladder
– Store and concentrate the bile produced by the liver (up
to tenfold) until it is needed in the small intestine
– In the concentration process, water and ions are absorbed
by the gallbladder mucosa