Hepatic Secretions Flashcards
How much bile is formed per day?
600-1200mL/day
What are the functions of bile?
- Aids fat digestion. Fats are not water soluble so need a detergent to break them down
- Route for metabolic excretion, cholesterol and bilirubin
- Neutralises duodenal acidity.
What cells form bile?
Hepatocytes
Where is bile stored?
Gallbladder
Functions of the liver
Main role is the digestion of food
- Regulates metabolism of COH , lipids and proteins
- Glycogen storage, stores excess blood glucose
- Production of ketone bodies (which are a byproduct of fatty acid metabolism)
- Ammonia to urea
- Synthesis of plasma proteins
- Storage of iron and vitamin A, D, B12
- Detoxification of drugs
Composition of bile
- 50% Bile acids
- 40% Phospholipids
- 4% Cholesterol
- 2% Bile pigments (bilirubin)
Where is bilirubin primarily derived from?
Metabolic breakdown of haemoglobin. Most of this haemoglobin comes from aged RBCs that are disposed of by cells of the reticuloendothelial system
Musculature of the Sphincter of Oddi
Thickening of circular muscles of the bile duct, located at the ductal entrance into the duodenum
How is bile concentrated in the gallbladder?
Reabsorption of NaCl which is accompanied by water, concentrating the bile
How much fluid can the human gallbladder accumulate?
20-50mL of fluid
What is CCKs role in the release of bile?
Contracts the gallbladder by binding to receptors located directly on the smooth muscle cells.
What happens with bile secretion in the period between meals?
Gallbladder is readily distensible and the sphincter of odd is contracted, therefore bile flows towards the gallbladder not the duodenum
What happens to bile secretion after a meal?
Humoral (CCK) and neural stimuli cause contraction of the gallbladder and the relaxation of the sphincter of odd. Thus more fluid flows towards the bowel. Bile acid from the liver increases as bile acids are returned via the enterohepatic circulation.
How much bile is extracted and recycled in the enterohepatic circulation?
95%
