Lipolysis and Ketogenesis Flashcards
Describe how adipose tissue is hormonally active
-It secretes leptin which stimulates energy usage and limits food intake. it also produces cytokines and estrogens
-Produces adiponectin which regulates glucose levels and fatty acid breakdown
How does brown adipose tissue participate in thermogenesis?
in brown adipocytes, fatty acids stimulate the production of thermogenin which uncouples the movement of protons moving down their gradient from the synthesis of ATP thus allowing the energy generated to be dissipated as heat
What regulates lipolysis in adipocytes?
hormone sensitive lipase
What is the function of hormone sensitive lipase?
it hydrolyzes TG to free fatty acids and glycerol
What stimulates HSL?
glucagon, epinephrine, and norepinephrine
What inhibits HSL?
insulin
When does ketogenesis occur?
When there is a high rate of fatty acid oxidation in the liver
What are the two ketone bodies?
acetoacetate and 3 hydrobutyrate
True/False ketone bodies can cross the blood brain barrier and placenta
true
What are the two enzymes associated with ketone body formation?
acetoacetate: HMG-CoA lyase
3-hydroxybutyrate: 3-OH-Butyrate dehydrogenase
Where does ketogenesis occur?
in the mitochondria of hepatocytes
How is acetoacetate utilized as fuel in tissues?
it is activated to acetoacetyl CoA , then thiolase splits this into two acetyl CoA molecules
How is 3-hydroxybutyrate utilized as fuel in tissues?
it is converted to acetoacetate then activated, then split by thiolase into 2 acetyl CoA molecules
What are the 3 main regulations of ketogenesis?
- The main regualtion is amount of circulating free fatty acids
-If the fatty acids are used in other ways in the liver(ie CO2 formation, esterification to TG, or oxidation)
-The energy needs of the cell
what is ketoacidosis?
When the body fails to adequately regulate ketone production causing increased levels of ketone bodies and decreased blood pH. Results from prolonged ketosis
