Chapter 3 (PBL) Flashcards
Which processes by the liver maintain steady blood glucose early on in a fast (prior to 12 hours) then after 1 day?
First glycogenolysis then after 12 hours, at reduced glycogen levels, then exclusively after 1 day, gluconeogensis
What metabolic changes occur during a prolonged fast (3-5 days), and how does that affect blood glucose, ketone body, and fatty acid levels?
Since the liver continues to produce ketone bodies and glucose via gluconeogenesis, but the muscle no longer uses ketone bodies and relies on fatty acids, serum ketone bodies rise. Since the brain begins to use ketone bodies for fuel, there is a reduces need for glucose, which reduces gluconeogenesis, and there is reduced protein breakdown. Serum glucose decreases slightly, ketone bodies increase greatly, and fatty acids increase slightly
What is the relationship between the liver and ketone bodies?
The liver produces them for the muscle and brain to use, but it cannot use them for fuel itself.
What are the carbon sources in gluconeogenesis?
lactate from exercising muscle, glycerol from fat degradation, and amino acids from protein breakdown
What is/are the fuel sources of red blood cells?
Glucose only, can only undergo glycolysis since they do not contain mitochondria
The muscle and most other tissues oxidize fatty acids into what?
Into carbon dioxide and water
The liver partially oxidizes fatty acids into what and then goes into what?
Into ketone bodies and then goes into the TCA cycle and then is fuel for the muscle and kidney
What is glycogenolysis?
Glycogen is degraded to glucose into the blood
What is lipolysis?
Adipose tissue is degraded and triacylglycerols are mobilized, releasing fatty acids and glycerol into the blood
What is the major fuel that is oxidized during overnight fasting?
Fatty acid
What is gluconeogenesis?
Production of new blood glucose from non-carb sources
Can fatty acids provide carbons for gluconeogenesis?
No, only glycerol from the triacylglycerol can provide carbons for gluconeogenesis
