Bile, gall bladder, gall stones and Jaundice Flashcards
Describe the path that bile takes from the liver
Label
How much bile made by liver per day?
600-1000ml
What is the capacity of the gallbladder?
30-50ml
Bile salts play a huge role in the digestion of fats. Explain what they do in this regard
- Most dietary lipids are not water soluble
- Pancreatic lipase is not lipid soluble funnily enough, so can only interact with lipids only at the surface of the lipid dropltet
- The larger the droplet, the more lipids inside
- Bile salts break apart the droplets, forming very tiny droplets, increasing the total surface area avaialble for enzymatic action
What type of the epitheium is found in the gall bladder?
Columnar
The gallbladder can store almost 12 hours worth of while. It does this by concentrating bile. How is this achieved?
- Water, sodium, cholride and most other small electrolytes are continously absorbed through the gallbladder mucosa, concentrating the remaining components.
- Most of this gallbladder absorption is caused by active transport of sodium, followed by secondary absorption of chloride ions, water and other components.
Where might you palpate the gallbladder?
State the man components of bile
- Bile salts
- Water
- Biliurbin
Cholesterol
Fatty acids
Lecithin
Sodium
Potassium
Calcium
Cholride
Bicarbonate
Another function of bile salts apart from emulsification is:
- Aid the absorption of fatty acids, monoglycerides, cholesterol and other lipids from the small intestine, by forming complexes with these lipids called MICELLES
Summarise how bilirubin is formed
- red blood cells break down after 120 days in spleen, most components are recycled
- Most parts are recycled
- Haem from haemoglobin is broken down into biliverdin
- Bilverdin is converted to uncojugated bilirubin
- Unconjugated bilirubin is not not soluble in water, so is bound to albumin in blood
- In the liver, bilirubin is conjugated to make it soluble, and is then excreted intotthe bile
Unconjugated bilirubin is conjugated through a two step process by which enzyme?
Uridine Diphosphatase Glucoronsyltransferase (UDT)
What disease is characterised by a mutation on chromosome two for the gene coding for the UGT enzyme?
Gilbert’s syndrome
- People with this can develop jaundice during fasting or times of stress.
As far as I can tell, bile salts and bile acids are the same thing - NOT TRUE SEE OPPOSITE CARD
The liver hydroxylates cholesterol to produce the bile acids chenodeoxycholic acid and cholic acid ( Fig. 29.9 ); these bile acids are then conjugated with the amino acids glycine or taurine to yield primary bile salts .
The liver makes about 6g of bile salts daily. Outline how bile salts are formed, and also go onto discuss how secondary bile acids are formed
- Bile salts are derived from cholesterol
- Cholesterol is first converted to cholic acid or chenodeoxychloic acid.
- These acids combine with either glycine or taurine, to form glyco and tauro-conjgated bile acids - the salts of these acids are then secreted into the bile
When these bile salts are secreted into the lumen of the intestine, bacterial partial dehydroxylation and removal of the glycine and taurine groups forms the secondary bile acids, deoxycholic acid and lithocholic acid. Cholic acid is converted into deoxycholic acid and chenodeoxycholic acid into lithocholic acid. All four of these bile acids can be taken back up into the blood stream, return to the liver, and be re-secreted in a process known as enterohepatic circulation
Explain the mechanisms by which gallbladder emptying is stimulated and inhibited
- Emptying of the bladder is a result of contractions, along with relaxation of the sphincter of Oddi
- The primary method for regulation of gallbladder contraction is Cholecystokinin
- CCK is produced by the duodenal mucosa as a result of chyme (although fat is the primary driver) entering the duodenum, enters the blood and then activates the gallbladder, whilst also promoting relaxation of the sphincter of Oddi
- The second way is Ach secreted by the vagus nerve and the inestinal enteric nervous system
- GB relaxation and closure of SO mediated by sympathetic nerves, and gut hormones vasoactive intestinal polypeptide (VIP) and somatostatin
Explain what is meant by enterohepatic circulation of BIle salts
- About 94% of bile salts are reabsorbed into the blood from the small intestine
- This will be absorped throught the small intestine, and will primarily occur in the Illeum by active transport into the PORTAL CIRCULATION
- Upon reaching the sinusoids, most are reabsorbed back into the hepatic cells and are re-secreted into the bile
- Any not absorbed in the illeum will be excreted, however this will be replenished by the luver
What are complications of gallstones in the small intestine?
Gallstone Ileus - A result of a fistula forming between the gall bladder and the small intestine
People with galllstones may present either with biliary colic or Acute Cholecystitis. Symptoms are similar, but have slight differences. Outline them
Key difference is the inflammation
What imaging tests can used for looking at biliary obstruction?
- Go to is ultrasound (good for liver, gallbladder, biliary system)
- CT
- MRI
What are potential causes of extrinsic compression of biliary structures
- Tumours of the pancreas and of lymph nodes
- Inflmammation - pancreatitis in particular
- Mirizzi syndrome (Mirizzi syndrome is a rare complication of prolonged cholelithiasis with presence of large, impacted gallstone into the Hartman’s pouch, causing chronic extrinsic compression of common bile duct (CBD))
Treatment for pancreatic cancer that compresses
- ERCP and place of a stent provides draininge of bile, relief of jaundice, bridge to therapy.
