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Liver and Gallbladder . pgs. 918 - 921. Liver and Gallbladder – Basics . Liver = heaviest gland of body - inferior to diaphragm Gallbladder – located i n a depression of the p osterior surface of l iver . Liver Anatomy .
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Liver and Gallbladder pgs. 918 - 921
Liver and Gallbladder – Basics Liver = heaviest gland of body - inferior to diaphragm Gallbladder – located in a depression of the posterior surface of liver
Liver Anatomy - Divided into left and right lobe by falciform ligament
Histology of Liver - Composed of specific epithelial cells = hepatocytes • Hundreds of hepatocytes are arranged in a six- sided structure called a lobule • Each lobule has a central vein and many sinusoids (blood passes) - Bile = secreted by hepatocytes (travels through bile canalicule and bile ducts)
Transport of Bile - Bile ducts merge to form left and right hepatic ducts
Gallbladder • composed of simple columnar epithelium • rugae (similar to stomach) • wall consists of smooth muscle – contractions force bile into cystic duct • Function: store and concentrate bile produced by liver
Bile - main components: water, bile salts, cholesterol, ions, and pigments - main pigment: bilirubin (derived from heme during destruction of worn RBCs) - bile salts – major role is emulsification – breakdown large lipid globules into small lipid globules (smaller surface area that allows pancreatic lipase to work); help absorb lipids
Emulsification and Bile Production • As digestion continues in small intestine; bile release continues • Between meals, bile is stored in gallbladder as sphincter of the hepatopancreatic ampulla is closed
Functions of Liver • Carb. metabolism – low blood glucose level = break down glycogen - high blood glucose (after eating) – convert glucose to glycogen and triglycerides 2. Lipid metabolism – break down F.A. to generate ATP; store triglycerides, synthesize lipoproteins (transport cholesterol) 3. Protein metabolism – deaminate amino acids so they can produce ATP, results in ammonia (NH3) converted to urea (excreted in urine)
Functions of Liver 4. Detoxify drugs and alcohols 5. Excrete bilirubin- secreted into bile and metabolized in small intestine by bacteria; excreted in feces (stercobilin) 6. Synthesis of bile salts (emulsification) 7. Storage of vitamins (A, B12, D, E, and K) 8. Phagocytosis of worn out RBCs 9. Help in activating Vitamin D (important in absorbing calcium)