Gallbladder + Bile

Question 1

Where is bile synthesised?

Answer 1

Liver

Question 2

Where is bile stored?

Answer 2

Gallbladder

Question 3

What is role of bile?

Answer 3

1. To emulsify fats

2. Serves as an excretory pathway for steroid hormones

Question 4

Where does the gall bladder lie?

Answer 4

At the junction of the right mid-clavicular line & costal margin

Question 5

What connects the liver to the gall bladder?

Answer 5

Cystic duct, branch of the common hepatic duct

Question 6

What is the functional unit of the liver?

Answer 6

The hepatic lobule

Question 7

What does a portal triad consist of?

Answer 7

Hepatic portal vein
Hepatic artery
Bile duct

Question 8

Which blood vessel runs up the centre of hepatic lobules?

Answer 8

Central vein

Question 9

Which liver blood vessel has fenestrated, discontinuous endothelium?

Answer 9

Hepatic sinusoid

Question 10

How are hepatocytes separated from the hepatic sinusoids?

Answer 10

By the space of disse

Question 11

Describe the blood content of hepatic sinusoids.

Answer 11

Contains oxygen-rich blood from the hepatic artery
Contains nutrient rich blood from the hepatic portal vein has come from small intestine where nutrients have been absorbed)

Question 12

Give the liver blood supply, both arterial and venous.

Answer 12

Arterial supply is from:
75% = hepatic portal VEIN
25% = hepatic artery

Venous drainage is via the hepatic vein.

Question 13

Name the cells which produce the extracellular matrix in the space of disse.

Answer 13

Stellate cells

Question 14

What is found between adjacent hepatocytes?

Answer 14

Bile canaliculi - not true vessels, more like grooves.

They are bound together by tight junctions, gap junctions & desmosomes

Question 15

Describe the pathway of bile into the GI tract.

Answer 15

1. Bile passes through the bile ducts in the hepatic lobules into either the left or right hepatic ducts which join to form the common hepatic duct
2. The cystic duct them joins the common hepatic duct to form the common bile duct. Allows bile to collect in the gall bladder
3. The pancreatic duct joins the common bile duct at the ampulla of vater
4. These two ducts then enter the duodenum at the major duodenal papilla
5. The sphincter of Oddi surrounds the two ducts to regulate the entry of bile into the duodenum

Question 16

Name the 6 components of bile.

Answer 16

Bile salts
Lecithin (a phospholipid)
HCO3
Cholesterol
Bile pigments
Trace metals

Question 17

What is the main role of bile salts?

Answer 17

They emulsify fats

Question 18

Why must bile salts be aggregated into micelles?

Answer 18

To reduce their damage on cell membranes until they are required

Question 19

Why is HCO3 contained within bile?

Answer 19

To neutralise the acids in the duodenum

Question 20

Which cells secrete bile salts, cholesterol, lecithin and bile pigments?

Answer 20

Hepatocytes

Question 21

Which cells secrete the HCO3?

Answer 21

Epithelial cells lining the bile ducts

Question 22

Which hormone stimulates the release of HCO3 by the bile ducts?

Answer 22

Secretin, in response to the acid of the duodenum

Question 23

Is bile more concentrated in the liver or the gall bladder?

Answer 23

Gall bladder

Question 24

Which hormone stimulates the gallbladder to contract and release bile?

Answer 24

CCK (cholecystokin). Also stimulates sphincter of Oddi to relax so bile can flow into the duodenum.

Question 25

Describe the vasculature of the gallbladder.

Answer 25

Arterial: Supplied by cystic artery Venous: No venous drainage, blood drains from the gallbladder directly into the liver

Question 26

Describe enterohepatic circulation.

Answer 26

1. During digestion of a fatty meal, the bile salts are absorbed via Na+ coupled transporters in the jejunum and terminal ileum 2. The absorbed bile salts return via the portal vein to the liver where they are secreted into bile again 3. The uptake of these bile salts into the hepatocytes is via secondary active transport coupled to Na+ 4. This recycling pathway is known as enterohepatic circulation. 5% of bile salts escape recycling and are lost in faces but the liver simply synthesises more bile salts from cholesterol

Question 27

From which molecule is bile synthesised from?

Answer 27

Cholesterol

Question 28

When is bile secretion at its greatest?

Answer 28

During and just after a meal

Question 29

What does it mean for the gall bladder to undergo adaptive relaxation?

Answer 29

The gallbladder increases in size with bile but the pressure doesn't increase as the bile duct is a low pressure system.

Question 30

What are bile pigments formed from?

Answer 30

The haem portion of haemoglobin when old erythrocytes are broken down.

Question 31

Name the predominant bile pigment. What colour is it?

Answer 31

Bilirubin - it is yellow

Question 32

Where does erythrocyte break down normally occur?

Answer 32

In the spleen and bone marrow by macrophages. Also occurs in the Kuppffer cells of the liver.

Question 33

Outline the steps of bilirubin metabolism.

Answer 33

1. Macrophage ingests the erythrocyte and haemoglobin is split into haem and globin 2. Globin is broken down to amino acids to be made into new erythrocytes in the one marrow 3. Haem is broken down by hemoxygenase into biliverdin, Fe2+ and CO 4. Fe2+ binds to transferrin and is used to make new erythrocytes 5. Biliverdin is reduced to unconjugated bilirubin by biliverdin reductase 6. Unconjugated bilirubin binds to albumin and travels to the liver. Glucoronic acid is added so it can be soluble and becomes conjugated bilirubin 7. Conjugated bilirubin dissolves in bile. When it reaches the ileum, it is reduced by bacteria to form urobilinogen 8. 10% of urobilinogen is reabsorbed into the blood and taken back to the liver to be oxidised to urobilin - makes urine yellow 8. 90% of urobilinogen is oxidised by other bacteria to form stercobilin - makes faeces brown

Question 34

What is jaundice?

Answer 34

Yellow discolouration of skin caused by a high serum bilirubin level

Question 35

Name the 3 types of jaundice

Answer 35

Pre-hepatic Hepatic Post-hepatic

Question 36

How is pre-hepatic jaundice caused? What are the symptoms?

Answer 36

Cause: Increased breakdown of erythrocytes, resulting in increased levels of unconjugated bilirubin. Caused by malaria, sickle cell anaemia, thalassaemia Symptoms: Yellow skin, enlarged spleen, normal stools and urine

Question 37

How is hepatic jaundice caused? What are the symptoms?

Answer 37

Cause: Hepatocellular swelling. Liver is damaged so cannot metabolise unconjugated bilirubin. Conjugated bilirubin cannot be secreted. Causes increase in conjugated and unconjugated bilirubin. Caused by parenchymal liver disease, viral hepatitis, alcohol hepatitis Symptoms: Dark urine, pale stools, enlarged spleen, yellow skin

Question 38

How is post-hepatic jaundice caused? What are the symptoms?

Answer 38

Cause: Biliary system is damaged. Results in increased conjugated bilirubin. Caused by gallstones, pancreatic cancer, pancreatitis (is pancreas is inflamed, it can obstruct the common bile duct) Symptoms: Dark urine, pale stools, yellow skin

Question 39

How are gall stones formed?

Answer 39

When the concentration of cholesterol is high, it will crystallise out of solution

Question 40

What are the consequences of having gall stones?

Answer 40

1. Stone may lodge in opening of gallbladder, causing painful spasms of the smooth muscle 2. Stone may lodge in common bile duct, preventing bile from entering the intestine. This causes decreased fat digestion and impaired absorption of fat soluble vitamins 3. Stone may lodge so pancreatic secretions and bile cannot enter the intestine. Will result in failure to neutralise acid and failure to digest, resulting in nutritional deficiencies.

Question 41

What controls the flow of bile and pancreatic enzymes into the duodenum?

Answer 41

Sphincter of Oddi

Question 42

Which nerve supplies parasympathetic innervation to the gallbladder?

Answer 42

Vagus nerve