Exam 2 Flashcards
lipoprotein lipase
enzyme found on vascular endothelial cells throughout the body, esp. adipose tissue, breaks down triglycerides from VLDLs and chylomicrons into fatty acids that can diffuse into adipocyte and reform triglycerides with glycerol. Insulin promotes the activity of lipoprotein lipase: insulin is the hormone that promotes fat storage.
What hormone promotes fat storage?
insulin
when needed in fasting state, what enzyme promotes the breakdown of stored triglycerides that the adipocyte can used to release free fatty acids and glycerol?
hormone-sensitive lipase
Glucose production in liver includes glycogenolysis and gluconeogenesis. What is the process of glycogenolysis?
breakdown of glycogen to produce G6P –> removal of phosphate –> generating free glucose that can leave the liver and enter blood stream.
Hepatic release of glucose by breaking down glycogen depends on the ability to remove phosphate from G6P, releasing free glucose
Glucose production in liver includes glycogenolysis and gluconeogenesis. What is the process of gluconeogenesis?
substrates generated by muscle and fat can enter a hepatic pathway that synthesizes new glucose
Gluconeogenic precursors include lactate and amino acids derived from muscle, and glycerol from fat cells. Fatty acids CANNOT be used for gluconeogenesis.
What cannot be used for gluconeogenesis?
fatty acids
In catabolism in liver needed for energy release during fasting, you can dephosphorylate the G6P, but in the catabolic pathway in MUSCLE, what happens?
G6P cannot be dephosphorylated but can undergo glycolysis and be converted to lactate. Lactate can travel though bloodstream to liver to serve as precursor for liver gluconeogensis.
liver –> release free bg
muscle –> create new bbg
What two precursors from muscle tissue are used by liver in gluconeogenesis?
lactate –> glycogenolysis
amino acids –> proteolysis
difference between glut 2 and GLUT 4 ?
glut 2 on liver cells transports glucose in either direction across cell. It doesn’t need insulin to move glucose into cells. GLUT 4 is sensitive to insulin in muscle and fat cells. WIthout GLUT 4, blood glucose levels stay high for longer periods of time after a meal. GLUT 2 moves glucose into lever cell relative to concentration on either side of membrane.
Where is glut 2 and glut 4 found?
glut 2 –> liver cells
glut 4 –> muscle and fat cells
secondary active transport does what with glucose?
removed it from GI tract and renal tubules. Hyperglycemia in DM may overwhelm number of transporters –> glucosuria
glycolysis process
glucose –> converted to G6P by enzymes –> G6P undergoes glycolysis, producing pyruvate –> pyruvate enters mitochondria –> with O2 available, pyruvate converts to acetyl Coa –> enters krebs cycle. electron transport chain produces most ATP
when the body is in fed state, what happens in liver?
glucose uptake via GLUT 2 and glycogenesis
GLYCOLYSIS occurs to break down glucose to make glycogen and increase acetyl CoA levels.
acetyl CoA used to make triglyceride (lipogenesis) and form VLDLS + cholesterol
ketogenesis
fatty acid released by ketone adipose lipolysis, oxidized bby liver, produce acetyl CoA and ketone bodies
high glucagon, low insulin. high stress hormone. used bby brain and not liver for fuel.
insulin secretion
increased plasma glucose is primary stimulus for insulin release –> glucose enters pancreatic B cells through GLUT 2 transporters –> glucose triggers a cascade of events resulting in exocytosis of vesicles containing insulin –> insulin then binds to its receptors on insulin-sensitive cells and triggers glucose uptake through GLUT 4 carriers
