Liver, pancreas and gall bladder Flashcards Preview

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Flashcards in Liver, pancreas and gall bladder Deck (27)
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Name some functions of the liver.

-Synthesize plasma lipoproteins
-Synthesize cholesterol
-Convert carbohydrates and proteins into fatty acids and triglycerides


what is the liver capsule?

The liver is covered by a collagenous connective tissue capsule, which is in turn covered by a layer of mesothelial cells (simple squamous epithelium) derived from the peritoneum


what segments make up the liver?



Describe lobules.

Hexagonal and has a branch of the hepatic vein called the centrolobular vein (or central vein) at its centre and portal triads at each corner


what makes up the portal triad?

-hepatic portal vein
-hepatic artery
-bile duct


what do the portal triads also typically include?

lymphatic vessels


what lines the bile duct?

lined by simple cuboidal cells called cholangiocytes


what are the main cells of the liver?



what are the spaces in-between hepatocytes?

sinusoids that allow blood to flow through


what is the hepatic acinus model of the liver?

the centre is of two joining lobules and not the central vein like it is for the classic lobule


what is the space of Disse?

the narrow space between the endothelial cells that line sinusoids and the hepatocytes


what are the portal tracts accompanied by?

collagenous connective tissue


what are kupffer cells?

resident macrophages scattered within the sinusoids and these cells removes particulate matter from the blood and help remove worn out red blood cells


what is bile?

alkaline solution containing water, ions, phospholipids, bilirubin and bile salts


what produces bile?



what is the direction of bile flow?

Bile flows via bile canaliculi toward the bile ducts in the portal tracts and thence to the hepatic ducts


How are bile canalculi formed?

formed by tight junctions in the cell membranes of adjacent hepatocytes


what is the structure of the gall bladder?

muscular sac which:
Is lined by simple columnar epithelium backed by a lamina propria of loose connective tissue rich in blood vessels and lymphatic vessels, a coat of smooth muscle and an outer collagenous layer of adventitia


what is the function of the gall bladder?

About 80%-90% of the volume of the bile arriving from the liver is removed by the gall bladder. This is done by actively pumping Na and Cl ions from the bile into the spaces between adjacent epithelial cells. Water then follows due to the increase in osmotic pressure in these spaces, which become distended with fluid when the gall bladder is actively concentrating bile. The water is carried away, largely by the lymphatic vessels of the lamina propria

The gall bladder is stimulated to contract and deliver bile to the duodenum, both under nervous control (chiefly vagal), and via release of the hormone cholecystokinin by endocrine cells of the duodenum when fatty food enters it


what is the gall bladder lined by?

tall columnar epithelial cells with a brush border


what is unusual about the pancreas?

it is both an exocrine and an endocrine gland


Describe the exocrine aspect of the pancreas.

produces about a litre of digestive juices containing proteases to break down proteins, lipases to break down lipids, nucleases to breakdown DNA/RNA, amylase to break down starch, etc, each day. These enter the duodenum via the pancreatic duct


Describe the endocrine aspect of the pancreas.

consists of small, scattered islands of tissue called islets of Langerhans, which produce a number of hormones including insulin and glucagon. Islets make up about 1%-2% of the pancreas


Describe the exocrine pancreas microscopically.

Has numerous serous acini and ducts. The cells are very basophilic because they contain large amounts of RER


how is the exocrine pancreas divided into lobules?

The pancreas has a thin connective tissue capsule that is continuous with connective tissue septa that divide the gland into lobules


Describe the basal and apical parts of the exocrine pancreas.

The basal part of the cells of the pancreatic acinus are typically basophilic due to extensive RER, while the apical part is often very eosinophilic due to the presence of zymogen (pre-enzyme) granules


what is the main pancreatic duct and what path does it take?

hepatopancreatic ampulla joins the common bile duct and opens into the duodenum on a papillae