Lecture 15

Question 1

Accessory organs to GI tract?

Answer 1

Pancreas, liver, gallbladder

Question 2

Function of pancreas?

Answer 2

Exocrine (99%): secretes enzymes into duodenum to break down food
Endocrine (1%): releases hormones (insulin/glucagon/somatostatin) into bloodstream affecting carb metabolism

Question 3

Role of acinar cells?

Answer 3

Secrete enzymes/fluid into duct system of pancreas

Question 4

Structure of duct system?

Answer 4

Pancreatic duct fuses with bile duct on entry to duodenum

Question 5

Pancreatic juice (aqueous component)?

Answer 5

200-800ml secreted each day, rich in bicarbonate (pH~8) -> helps to neutralise acidic chyme as it enters duodenum, secretion stimulated by secretin

Question 6

Pancreatic juice (enzymatic component)?

Answer 6

Proteolytic enzymes, pancreatic amylase, lipolytic enzymes

Question 7

Proteolytic enzymes?

Answer 7

Split peptides, secreted in inactive form (activated by enterokinase) e.g. trypsin

Question 8

Pancreatic amylase?

Answer 8

breaks down starch, secreted in active form

Question 9

Lipolytic enzymes?

Answer 9

Lipase secreted in active form (activated by trypsin in duodenum) e.g. colipase/cholesterol esterase

Question 10

Control of pancreatic secretions?

Answer 10

Cephalic phase: nervous reflex
Gastric phase: gastrin released in response to stomach digestion
Intestinal phase: secretin and Cholecystokinin released by mucosa in response to chyme in duodenum

Question 11

Pancreatitis?

Answer 11

Pancreatic enzymes activated withing pancreases (organ attacks itself)

Question 12

Causes of pancreatitis?

Answer 12

Gallstones, alcohol abuse, unknown cause (idiopathic)

Question 13

Treatment for pancreatitis?

Answer 13

Pain management, electrolyte therapy (nutrients/salts balanced)

Question 14

Some functions of liver (has many)?

Answer 14

Process digested food from intestine, manufacture bile, convert excess monosaccharides to glycogen, stores iron/vitamins, metabolise drugs/break down poisons

Question 15

Kupffer cells?

Answer 15

Phagocytic cell - eat/surround toxic substance

Question 16

Structure of liver?

Answer 16

Hepatic (liver) cells around central vein, hepatocytes make up functional units lobules, lobules form two main lobes of liver

Question 17

Role of hepatic cells?

Answer 17

Extract oxygen/most nutrients, detoxify/store poisons + drugs, secrete products into hepatic vein (except bile)

Question 18

Hepatic blood supply?

Answer 18

Receives double blood supply (oxygenated from hepatic artery, deoxygenated (nutrient rich) from portal vein)

Question 19

Bile?

Answer 19

Excretory product of liver metabolism/digestive secretion

Question 20

Where can bile go?

Answer 20

Go straight to duodenum or stored in gallbladder - determined by presence of fat

Question 21

Bile salts?

Answer 21

Emulsify fat into small droplets (as fat is in aqueous environment)

Question 22

Bile cholesterol?

Answer 22

Made soluble by salts

Question 23

Bile pigments (bilirubin)?

Answer 23

Are yellow/brown - gives urine/faeces their colour, absorbed from blood

Question 24

Where are bile salts, cholesterol, pigments secreted from?

Answer 24

Liver cells - hepatocytes

Question 25

What is secreted from epithelial cells lining bile ducts?

Answer 25

Bicarbonate ions - neutralise acidic chyme

Question 26

Circulation of bile salts?

Answer 26

Travel down bile duct: if stomach empty then stored, if fat in duodenum then used to emulsify in digestion (then reabsorbed/recirculated)

Question 27

Function of gallbladder?

Answer 27

Stores/concentrates bile by extracting water/ions - can lead to increased insoluble cholesterol levels (gallstones)

Question 28

Entry of bile into gallbladder?

Answer 28

Enters by cystic duct when small intestine is empty

Question 29

Ejection of bile from gallbaldder to duodenum?

Answer 29

Occurs when protein/fat-rich chyme enters duodenum (causes CCK release)

Question 30

Role of CCK (cholecystokinin) in gallbladder?

Answer 30

Causes it to contract + sphincter of Oddi to relax allowing bile to enter duodenum

Question 31

Gallstones?

Answer 31

Crystalline deposits, accumulate when too much cholesterol + not enough bile salts

Question 32

Treatment for gallstones?

Answer 32

Small: can be dissolved
Severe: gallbladder can be removed (cholecystectomy)

Question 33

Why jaundice symptom of gallstones?

Answer 33

Stones block common bile duct so increased bilirubin (pigment) in blood plasma