The Liver Flashcards
(50 cards)
Summarise the gross structure and anatomy of the liver:
- Split into four lobes, functionally split into two
- Diaphragmatic surface on top
- VIsceral surface below, gallbladder located here
- Portal vein carries nutrient-rich blood
- Central vein removes deox blood from liver
- Hepatic artery supplies nutrients and ox to liver
- Bile ducts feed into gallbladder
What is the portal triad? What is its function?
Group of three tubular structures: The bile duct, portal vein and hepatic artery. Responsible for moving resources around the liver.
What cells are responsible for the liver’s immune function?
Kupffer cells
What is the functional unit of the liver?
Hepatic lobule
Describe the micro-structure of the liver:
- Comprised of lobules (functional unit) containing hepatocytes and Kupffer cells
- Bile and blood pass on different sides of the hepatocytes
Why does the liver receive blood from both the hepatic portal vein and the hepatic portal artery?
Hepatic portal vein provides nutrient rich blood from the GI tract which must be processed and have its contents metabolised.
Hepatic artery provides oxygen from the tract.
Why does the liver receive blood from the GI tract?
Because it processes, balances and metabolises its contents before they reach the heart and it enters systemic circulation.
What is meant by the exocrine function of the liver?
The synthesis and secretion of bile into the gallbladder for use in the GI tract.
What are the main components of bile? What are their functions?
Bile salts - Emulsifies fats, making them soluble
Cholesterol - Aids emulsification
Phospholipids - Limits bile salt toxicity
HCO3- - Neutralises stomach acid
What is enterohepatic recycling/circulation? Why does it occur?
The process by which bile salts are secreted into the GI tract and reabsorbed into the liver.
It reduces the energy spent synthesising bile compounds by recycling them.
Why is enterohepatic circulation important in pharmacology?
Certain drugs are reabsorbed along with the bile by the liver, increasing bioavailability by increasing circulatory exposure.
Describe the bile cycle in the liver, gallbladder and GI tract.
- Liver secretes bile into the gallbladder via the common hepatic and cystic ducts
- Gallbladder concentrates then secretes bile into duodenum via common bile duct
- Bile reabsorbed in the ileum and sent to the liver via the hepatic portal vein
What role does cholesterol play in the liver? If it is used by the liver why is it harmful to have too much cholesterol?
Cholesterol is used by the liver to produce bile.
If you have too much cholesterol it builds up in arteries forming a plaque that raises blood pressure.
Explain how dietary fibre has a positive impact on the body through cholesterol.
- Dietary fibre sequesters bile
- Bile contains cholesterol
- Sequestered bile isn’t recycled and is eliminated
- Thus, cholesterol is eliminated from the body, lowering cholesterol levels
What is the basis of most cholesterol lowering drugs? Why?
Fibre function since it eliminates cholesterol from the body by. preventing bile recirculation.
Why is it important that cholesterol doesn’t fall too high when taking cholesterol lowering drugs?
Cholesterol is required for membrane stability, bile synthesis and steroid hormone synthesis. A low cholesterol level would impact all of these vital functions.
Why are some sources of cholesterol defined as “good” whilst others are defined as “bad”?
Plasma cholesterol is bad (raises BP). Cholesterol inside the liver is good. Cholesterol from different food sources ends up in different locations and is thus defined as good or bad.
What are LDLs? Are they good or bad? Why?
Low density lipoproteins. They are cholesterol carriers which deliver cholesterol to cells.
BAD because they raise plasma cholesterol.
What are HDLs? Are they good or bad? Why?
High density lipoproteins. They are cholesterol carriers which remove cholesterol from plasma and delivers it to the liver.
GOOD because they decrease plasma cholesterol.
What is atherosclerotic disease?
Deposition of cholesterol in artery walls which increases risk of heart attack.
What are some factors that lower the LDL to HDL ratio? What impact does this have?
- Weight loss
- Oestrogen
Decreases risk of atherosclerotic disease.
What are some factors that raise the LDL to HDL ratio? What impact does this have?
- Smoking
- Weight gain
Increases risk of atherosclerotic disease.
What is hypercholesterolaemia? How does this raise the risk of athersclerotic disease?
A genetic decrease in LDL receptor expression.
These receptors are necessary to take up LDLs and reduce plasma cholesterol. Without them plasma cholesterol increases, thereby raising the risk of atherosclerotic disease.
