Liver, pancreas and gall bladder

Question 1

Name some functions of the liver.

Answer 1

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

Question 2

what is the liver capsule?

Answer 2

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

Question 3

what segments make up the liver?

Answer 3

lobules

Question 4

Describe lobules.

Answer 4

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

Question 5

what makes up the portal triad?

Answer 5

• hepatic portal vein
• hepatic artery
• bile duct

Question 6

what do the portal triads also typically include?

Answer 6

lymphatic vessels

Question 7

what lines the bile duct?

Answer 7

lined by simple cuboidal cells called cholangiocytes

Question 8

what are the main cells of the liver?

Answer 8

hepatocytes

Question 9

what are the spaces in-between hepatocytes?

Answer 9

sinusoids that allow blood to flow through

Question 10

what is the hepatic acinus model of the liver?

Answer 10

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

Question 11

what is the space of Disse?

Answer 11

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

Question 12

what are the portal tracts accompanied by?

Answer 12

collagenous connective tissue

Question 13

what are kupffer cells?

Answer 13

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

Question 14

what is bile?

Answer 14

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

Question 15

what produces bile?

Answer 15

hepatocytes

Question 16

what is the direction of bile flow?

Answer 16

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

Question 17

How are bile canalculi formed?

Answer 17

formed by tight junctions in the cell membranes of adjacent hepatocytes

Question 18

what is the structure of the gall bladder?

Answer 18

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

Question 19

what is the function of the gall bladder?

Answer 19

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

Question 20

what is the gall bladder lined by?

Answer 20

tall columnar epithelial cells with a brush border

Question 21

what is unusual about the pancreas?

Answer 21

it is both an exocrine and an endocrine gland

Question 22

Describe the exocrine aspect of the pancreas.

Answer 22

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

Question 23

Describe the endocrine aspect of the pancreas.

Answer 23

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

Question 24

Describe the exocrine pancreas microscopically.

Answer 24

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

Question 25

how is the exocrine pancreas divided into lobules?

Answer 25

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

Question 26

Describe the basal and apical parts of the exocrine pancreas.

Answer 26

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

Question 27

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

Answer 27

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