Digestive 4

Question 1

Liver functions

Answer 1

o Produces and secretes bile.
o Receives substances absorbed by the intestines
through portal circulation.
o Processes/stores nutrients, minerals, and glucose
(glycogen); controls when to put these into blood.
o Detoxifies ingested toxins (e.g. alcohol, drugs).
o Breaks down old RBCs & produces blood proteins.

Question 2

ANTERIOR liver

Answer 2

o Anteriorly, liver is divided into left and right lobes.
o Lobes separated by a falciform ligament, which connects liver to anterior abdominal wall.
o Inferiorly, falciform ligament is continuous with round ligament (ligamentum teres), which is remnant of umbilical vein. Connects to umbilicus.
o Superiorly, falciform ligament turns into coronary ligament, which attaches to diaphragm.

Question 3

SUPERIOR liver

Answer 3

o Coronary ligament reflects superiorly onto diaphragm.
o Bare area of liver: Area bounded by the coronary ligament and triangular ligaments, not covered by peritoneum (liver directly touching diaphragm).
o Triangular ligaments: formed at left and right angles of coronary ligament.

Question 4

POSTERIOR liver

Answer 4

o Two more lobes:
• Caudate lobe (between inferior vena cava and venous ligament of the liver (ligamentum venosum)
• Quadrate lobe (between gallbladder and round ligament)

Porta hepatis: site where portal triad enters/exits the liver. The portal triad consists of:
o Hepatic artery (supplies oxygenated blood to liver)
o Hepatic portal vein (brings nutrient-rich blood from intestines to liver)
o Common hepatic duct (carries bile away from liver toward duodenum).

Question 5

Lesser omentum

Answer 5

double-layer of peritoneum connecting liver with lesser curvature of stomach and first part of duodenum.
The portal triad runs within the lesser omentum to get to the porta hepatis.

Question 6

BLOOD

Answer 6

Blood from portal vein (3/4, nutrientrich) and hepatic artery (1/4, O2-rich) percolate through hepatocyte plates (via large capillaries called sinusoids).

Cleaned blood then reaches a central vein in middle of lobule. Central veins empty into hepatic veins that drain
liver (into inferior vena cava).

Question 7

BILE

Answer 7

o Bile produced by hepatocytes is secreted into bile canaliculi (channels between hepatocytes), which merge to form biliary ducts.
o Biliary ducts unite to form left and right hepatic ducts, which drain bile from left and right lobes of liver.
o Left and right hepatic ducts converge at porta hepatis to form the common hepatic duct.

Question 8

CIRRHOSIS

Answer 8

o Destruction of hepatocytes, replaced by tough scar tissue. Liver becomes hard and nodular due to scar tissue.
o Blood flow through liver becomes inefficient, leading to portal hypertension.
o Causes:
• Alcohol (most common)
• Viruses (hepatitis C)
• Drugs/medications
• Autoimmune disease

Question 9

JAUNDICE

Answer 9

o Hepatocytes decompose old RBCs. Convert heme
(protein in hemoglobin) into a yellow-green substance called bilirubin, which is excreted in bile.
o Bilirubin gives bile its yellow/green colour and is oxidized in intestines to give feces its brown colour.
o A diseased liver cannot process and excrete bilirubin
efficiently, leading to high bilirubin in circulation.
o Jaundiced patients have yellowish skin and eyes,
and clay-coloured feces.

Question 10

The gallbladder has 3 parts:

Answer 10

o Fundus (rounded inferior part)
o Body (middle part)
o Neck (narrow superior part)

Question 11

cystic duct

Answer 11

connects neck of gallbladder with hepatic duct. Bile drains into and out of the gallbladder by this duct.
runs in layers of lesser omentum to join common hepatic duct.

Question 12

bile duct

Answer 12

Once cystic duct and common hepatic duct unite, the bile duct is formed. Bile duct transports bile from liver/gallbladder to duodenum.

Question 13

Bile:

Answer 13

yellow/green alkaline solution that emulsifies (breaks down) fats.

Question 14

Gallstones

Answer 14

o Gallstones form when cholesterol, bilirubin, and other substances in bile crystallize to make stones.
o May not cause any pain; but if lodged in cystic or bile duct, can cause severe abdominal pain and block bile
from reaching the duodenum.
o If recurrent, may need to have gallbladder removed (cholecystectomy).

Question 15

Pancreas:

Answer 15

an elongated, flat gland found in the upper left abdomen behind the stomach and between the
duodenum and spleen.

Question 16

ANATOMY pancreas

Answer 16

o Five parts:

1) Head (expanded part close to duodenum)
2) Uncinate process (hook-shaped projection of head of pancreas)
3) Neck (small part adjacent to pylorus)
4) Body
5) Tail (left-most part close to spleen)

Question 17

The pancreas performs two major functions:

Answer 17

o Exocrine function: produces pancreatic juice, which contains enzymes essential for digestion.
o Endocrine function: produces hormones (insulin and glucagon) that control blood glucose levels.

Question 18

EXOCRINE

Answer 18

o Most (~95%) of pancreas is acinar cells
arranged in acini (sacs).
o Acinar cells make pancreatic juice containing:
• Enzymes (amylase, trypsin, chymotrypsin) that
break down starch and protein.
• Bicarbonate, which neutralizes gastric acid.
o Enzymes are stored and secreted as zymogens (inactive enzymes). Zymogens move from acinus via intralobular ducts to main pancreatic ducts.
o Zymogens are active once they reach acidic environment of duodenum.

Question 19

ENDOCRINE

Answer 19

o Endocrine pancreas comprises 5% of thec ells arranged in islets (of Langerhans).
o These cells produce:
• Insulin (decreases blood glucose).
• Glucagon (increases blood glucose).
• Somatostatin (slows down digestion, inhibits insulin and glucagon production).
o Islet cells secrete these hormones directly into the bloodstream.

Question 20

Insulin

Answer 20

is the hormone that lowers blood glucose (facilitates glucose entry into cells).

Question 21

Diabetes

Answer 21

absence or insufficient insulin production, or an inability of cells to properly use insulin, leading to high blood sugar levels

Question 22

pancreatic ducts

Answer 22

Main pancreatic duct + Bile duct => hepatopancreatic ampulla (of Vater). => major duodenal papilla.

Question 23

hepatopancreatic ampulla (of Vater).

Answer 23

Main pancreatic duct joins with bile duct, and together they form hepatopancreatic ampulla (of Vater).
Hepatopancreatic ampulla drains into duodenum at major duodenal papilla.

Question 24

Hepatopancreatic sphincter (of Oddi)

Answer 24

surrounds this duct and controls flow of bile and pancreatic juice into duodenum.
Controls entry of bile and pancreatic juice through major duodenal papilla.

Question 25

PANCREATITIS

Answer 25

o Pancreatitis is inflammation of pancreas, often due to premature release/activation of pancreatic juice that eats away at acini.
o Causes:
• Blockage of bile duct/hepatopancreatic ampulla (e.g. gallstones)
• Alcohol
• Viruses
• Trauma (injury to pancreas)
o Can be sudden (acute) or chronic, and very painful!

Question 26

Pancreatic duct summary

Answer 26

oLeft and right hepatic ducts combine to form common hepatic duct, which carries bile from liver.
oCystic duct carries bile to/from gallbladder.
oBile duct is formed after cystic duct joins common hepatic duct.
oMain and accessory pancreatic ducts drain pancreas.
oMain pancreatic duct joins with bile duct to form hepatopancreatic ampulla. It empties into duodenum at major duodenal papilla. oAccessory pancreatic duct empties into duodenum separately at minor duodenal papilla.

Question 27

PANCREATIC

CANCER

Answer 27

o Uncontrolled proliferation of cells in pancreas.
o Most commonly associated with: smoking, pancreatitis/inflammation, diabetes, age (70+).
o Most common: adenocarcinoma (acinar cells).
o Difficult to detect until advanced stage. Thus, when detected it has usually spread to other tissues, so has a high mortality rate.
o In Canada: 12th highest incidence, 4th deadliest.