Pancreas and Liver

Question 1

What is the exocrine function of the liver and pancreas?

Answer 1

Act as an accessory organ for intestines by providing excretions directly into the luman of the small intestine

Question 2

What is the endocrine function of the pancreas and liver?

Answer 2

Regulates blood borne energy substrate availability (such as glucose) via hormones

Question 3

What makes the pancreas difficult to reach?

Answer 3

Its a reteroperitoneal organ which is surrounded by many major blood vessels.

Question 4

Name the main blood supplies for the pancreas

Answer 4

The splenic artery (from the coeliac trunk) and the pancreatico-duodenal arteries. (from the superior mesenteric artery or the coeliac trunk)

Question 5

Name the primary function of the exocrine pancreas

Answer 5

It secretes fluid that neutralises acid (secretions enter just after the stomach) and it delivers enzymes for macronutrient digestion in the duodenum.

Question 6

Describe the features of acinar cells

Answer 6

They are the main secretory cells which are clustered around an intercalated duct , these intercalated ducts all converge into the intraglobular duct. Acinar cells also add ions to secretions.

Question 7

The exocrine secretions of the pancreas are regulated depending on the stage of digestion. Explain how they are regulated at the different stages of digestion

Answer 7

Cephalic - Vagus nerve stimulates panreatic secretuins by releasing acetylcholine (ACh) and VIP.
Gastric - secretions are controlled by vasovagal reflexes
Intestinal - secretions controlled by secretin and CCK.

Question 8

Describe the role of Zymogen granules in Acinar cells

Answer 8

They house inactive/actice digestive enzymes. They are secreted in response to CCK, VIP and gastrin-releasing peptide. With activation, zymogen granuels are exocytosed from acinar cells directly into the luminal space.

Question 9

How is exocytosis of zymogen granuels controlled?

Answer 9

Hormonally or neurally

Question 10

Where does ion secretion occur in the pancreas?

Answer 10

In Acinar cells and intercalated duct cells.

Question 11

Explain how ions are added by acinar cells

Answer 11

Basolateral CCK and ACh binding stimulates Cl- transport across apical membrane. This facilitates the movement of sodium ions and water.

Question 12

Explain how ion secretion occurs in intercalated ductal cells

Answer 12

Secretin and ACh bind in ductal cells which activates cystic fibrosis transmembrane conductance regulators, Chloride channels, chloride bicarbonate ion co-transporters. The transporters recycle chloride and bicarbonate ions.

Question 13

Describe what happens when there us an increased flow rate of ionic concentration

Answer 13

Conc of bicarbonate ions increases but conc of chloride ions decreases. Potassium and sodium ion conc remains unaffected.

Question 14

Describe the position of the liver in the abdomen

Answer 14

Lies across upper abdomen, under the diaphragm. It is surrounded by peritoneum except the bare area which may be palpable under the costal margin.

Question 15

What supplies the liver with nutrients and where do they come from?

Answer 15

It is supplied by the hepatic portal vein which brings absorbed nutrients from the stomach and gut.

Question 16

What supplies hepatocytes with oxygen?

Answer 16

The hepatic artery

Question 17

How is bile drained?

Answer 17

Via canaliculi that lie between the hepatocytes into bile ductules and eventually into bile ducts.

Question 18

What is the liver surrounded by?

Answer 18

Glisson’s capsule, this is a thin connective tissue with extensions into the organ between the lobules

Question 19

Describe the structure of the liver

Answer 19

It has right and left lobes which are separated by the falciform ligament and a quadrate lobe next to the gall bladder.

Question 20

Describe the functions of the Liver

Answer 20

Synthesis and secretion of bile, Storage of glucose, glycogen, proteins, vitamins and fats. Detoxification of metabolic waste, and synthesis of blood clotting and anticoagulant factors

Question 21

What are the main constituents of bile?

Answer 21

Bile pigments (mainly bilirubin), cholesterol, phospholipids, fatty acids, water and electrolytes.

Question 22

What are bile pigments made up from and what cells play a role in their formation.

Answer 22

Bile pigments are derived from the breakdown products of haemoglobin. Kupffer cells play a role in formation.

Question 23

What allows for the absorption of fats across the intestine wall?

Answer 23

Bile salts. They are responsible for the detergent and emulsifying effect on fats since fats cannot be absorbed unless broken down and held in an emulsion.

Question 24

what do bile ducts form?

Answer 24

The common hepatic duct

Question 25

Describe the travel of bile and what controls its path

Answer 25

Bile goes from the common bile duct into the duodenum or the pancreas. This direction is controlled by the Sphincter of Oddi, if contracted the bile will enter the gallbladder, if relaxed it will travel mainly to the duodenum.

Question 26

What is relaxation of the Sphincter of Oddi controlled by?

Answer 26

CCK.

Question 27

Describe the role of the gallbladder and what causes it to secrete bile

Answer 27

Stores concentrated bile and distributes it. The gallbladder contracts in response to CCK and squeezes out bile. Vagal stimulation causes weak gallbladder contraction.

Question 28

What inhibits bile acid secretion in the gallbladder

Answer 28

Somatostatin and noradrenaline

Question 29

Name some of the non-biliary liver function?

Answer 29

Metabolism of glycogen, protein and fat. Detoxification, key in removing ammonia, ethanol and drugs. Also immune system function, it removes intestinal bacterial from portal blood so it isn’t circulated around the body.