Review 9 Flashcards
Short and Long Fatty acids Absorption
- Short-chain fatty acids are absorbed across the intestine into the blood.
- Long-chain fatty acids are absorbed as micelles and assembled into chylomicrons for release into lacteals of the LYMPHATIC system and re-enter the bloodstream via the thoracic duct.
Hormone-sensitive lipase of Adipocytes Regulators
- Inhibitors - Insulin
2. Activators - Epinephrine and Cortisol
HDL function
Picks up cholesterol accumulating in blood vessels Delivers cholesterol to liver and steroidogenic tissues.
LDL Function
Delivers cholesterols into cells.
Cholesterol Metabolism Notes
- HMG-CoA reductase
- Activator - Insulin
- Inhibitor - Cholesterol
Fatty Acid Notes
- Occurs in liver and stimulated by Insulin.
2. Synthesized in the CYTOPLASM from acetyl-CoA transported from MITOCHONDRIA.
Citrate Lyase
Splits citrate into acetyl-CoA and oxaloacetate.
Fatty Acid Synthesis Acetyl-CoA carboxylase
- Rate limiting enzyme.
- Adds CO2 to acetyl-CoA to form malonyl-CoA
- Requires Biotin and Citrate.
- Activator - insulin and ATP
Fatty Acid Beta Oxidation
- Activator - Glucagon
2. Inhibitor - Insulin
Fatty Acid Beta-Oxidation Notes
- Occurs in mitochondria (some B-oxidation in peroxisome)
- Activation: fatty-acyl-CoA synthetase attaches fatty acid to CoA
- Fatty acids Transported into MITOCHONDRIA by the carnitine shuttle
- Short-chain fatty acids (two to four carbons) and medium-chain fatty acids (six to twelve carbons) diffuse freely into mitochondria. Long-chain fatty acids (14 to 20 carbons) require transport via a carnitine shuttle.
- β-oxidation uses cycles of oxidation, hydration, oxidation, and cleavage
- Releases acetyl group and produces 1 FADH2 and 1 NADH.
LOOK AT DIAGRAM OF BETA-OXIDATION
PLEASE :-)
Ketogenesis vs. Ketolysis
Ketogenesis - Ketones form during a prolonged starvation state due to excess acetyl-CoA in the liver.
Ketolysis - Regenerates acetyl-CoA for use as an energy source in peripheral tissues.
Triglycerides Catabolism
- A 16 carbon fatty acid is cleaved 7 times and produces 7 FADH2 and 7 NADH as it is converted into 8 acetyl-CoA.
- Acetyl CoA enters into the Krebs cycle as usual.
- Glycerol backbone is converted into PGAL and used in glycolsis.
Homeostasis
- A physiological stable state that is maintained and adjusted, often with the expenditure of energy.
- Usually different from equilibrium
- Nervous tissue and red blood cells are INSENSITIVE to insulin and both tissues derive energy almost exclusively from GLUCOSE. Also, the nervous tissue may also use KETONES.
Insulin Notes
- Secreted by pancreatic BETA cells.
2. Increases the rate of anabolic metabolism.
Carbohydrates and Insulin
- insulin INCREASES the uptake of glucose and INCREASES carbohydrate metabolism in muscle and fat cells.
- Insulin INCREASES glycogen synthesis in the liver by increasing the activity of GLUCOKINASE and GLYCOGEN SYNTHASE while DECREASING the activity of enzymes that promote glycogen breakdown (GLYCOGEN PHOSPHORYLASE and GLUCOSE-6-PHATASE).
Glucagon Notes
- Secreted by pancreatic ALPHA cells
2. Activator - Low glucose and high protein.
Glucagon and Glucose
- INCREASES liver glycogenolysis, ACTIVATES glycogen phosphorylase and INHIBITS glycogen synthase.
- INCREASES liver gluconeogenesis. INCREASES the conversion of pyruvate to phosphoenolpyruvate by PYRUVATE CARBOXYLASE and PHOSPHOENOLPYRUVATE CARBOXYKINASE (PEPCK).
- INCREASES the conversion of fructose 1,6-bisphosphate to fructose 6-phosphate by fructose-1,6-bisphosphate.
- Increases liver ketogenesis and DECREASES lipogenesis.
- INCREASES lipolysis in the liver. Glucagon INCREASES hormone-sensitive lipase in the liver.
- Glucagon is not considered a major fat-mobilizing hormone.
LEARN INSULIN AND GLUCAGON RELATIONSHIP
Look at the handout
Glucocorticoids
- Increase blood glucose in response to stress (including exercise, cold, and emotional stress) by BREAKING DOWN fat stores, INCREASING gluconeogenesis and DECREASING glucose uptake.
Catecholamines
- INCREASE glycogenolysis and lipolysis -> INCREASE basal metabolic rate through their SYMPATHETIC nervous system activity..
- INCREASE the activity of liver and muscle glycogen phosphorylase.
Thyroid Hormone
- INCREASE basal metabolic rate.
- T3 is more potent than T4 (thyroxine) but have a shorter half-life.
- T4 is converted to T3 in tissues.
Hypothyroidism
Cold intolerance, fatigue, weight gain, and depression
Hyperthyroidism
Weight loss, anxiety, jitteriness, and fever
Glucose Synthesis Source
Lactate
Glycerol
Amino Acids