CPPS303 XIAO Lecture 3 Liver Lipid 1 March_14_2025 (1) (1) (1) Flashcards
What is the role of the liver in lipid homeostasis?
The liver synthesizes and secretes very-low-density lipoprotein (VLDL) and is the major organ for cholesterol synthesis, bile acids synthesis and secretion, and uptake of various lipoproteins.
What is enterohepatic circulation?
The enterohepatic circulation refers to the recycling of bile acids, which are synthesized in the liver, stored in the gallbladder, released into the duodenum, absorbed in the intestine, and returned to the liver.
What are the components of very-low-density lipoprotein (VLDL)?
VLDL is composed of:
* TAG
* Phospholipids
* Cholesterol
* Cholesteryl esters (CE)
* Proteins
What causes steatosis (fatty liver)?
Steatosis occurs due to an imbalance of lipid influx and efflux.
Fill in the blank: The liver is a major tissue for LDL uptake, accounting for _____% of total uptake.
40~60%
What happens to triglycerides in chylomicrons at adipose and muscle tissues?
Triglycerides are removed from chylomicrons via lipoprotein lipase (LPL).
What is the primary site for active uptake of conjugated bile acids?
The ileum.
True or False: Only about 5% of bile acids are lost through fecal output.
True.
What is the function of microsomal triglyceride transfer protein (MTP) in VLDL synthesis?
MTP mediates lipidation of apoB100.
What happens to apoB100 in a lipid-poor state?
ApoB100 is degraded.
What is the main regulatory mechanism for VLDL synthesis and secretion?
Regulation occurs at the level of post-translation, not expression.
During the inter-digestive phase, what does the liver receive from adipose tissue?
Fatty acids and glycerol.
What are the main causes of hepatosteatosis?
Impairment of VLDL assembly and secretion, leading to triglyceride accumulation in lipid droplets.
What is the relationship between liver steatosis and the VLDL secretory pathway?
Impairment of VLDL assembly and secretion causes triglycerides to be stored in lipid droplets, leading to hepatosteatosis.
What are the inputs for TAG metabolism in the liver?
Fatty acid flux (from adipose lipolysis), dietary fat (chylomicron remnants, FAs), and de novo lipogenesis (DNL).
The liver plays a key role in whole-body lipid homeostasis. What are the three main areas of focus?
Enterohepatic circulation of bile acids, VLDL synthesis and secretion, and regulation of TAG sources.
Fill in the blank: If input exceeds output in TAG metabolism, it leads to _____
Steatosis.
