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Description
Flashcards by Mark Arsenal, updated more than 1 year ago
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Created by Mark Arsenal
about 11 years ago
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| Question | Answer |
| Explain the Randle Cycle (Glucose/Fatty Acid Cycle)? | This is whereby in Glucose metabolism we form high levels of Citrate through Acetyl-CoA breakdown in TCA. When Citrate builds up it is converted to Malonyl-CoA which inhibits CPT1 (allows fat to enter the cell for breakdown) and thus when Glucose Metabolism is high fat metabolism is low. Additionally a build up of Citrate also inhibits PFK (Glycolysis) to prevent further production of Acetyl CoA (through Pyruvate breakdown) and thus additional Citrate formation in the TCA. |
| What relationship do Insulin and Glucagon have? | Glucagon is the antagonist of Insulin. Insulin causes formation of Glygogen, whereas Glucagon stimulates the breakdown of Glycogen. |
| Why is there a flux between energy storage and release? | Because energy demand is constant, whereas energy intake is not. |
| What are the 4 states of feeding? | Fed State= 3-6 hours after a meal, Postabsorbative= 3-6-->12-18 hours after a meal, Fasting State= 18hrs-2 days after a meal, Starvation= 3 days --> 2 weeks after a meal. |
| How is Insulin key in Glucose Homeostasis? | After a meal blood Glucose increases which signals the Pancreas to release Insulin which in turn decreases blood Glucose through increasing Glucose uptake by the Liver where it is converted to Glycogen. |
| What hormone is released to cause breakdown of Glycogen to form Glucose? | Glucagon- When blood Glucose is low Glucagon acts as signal to the Pancreas which breaks down Glycogen to Glucose (Glycogenolysis) to increase Blood Glucose. |
| What are the characteristics of the Fed State? | Glucose from food is high so acts as our largest energy source, because of this we store fat. AA's are used to make functional proteins. The focus is on Glycogenesis (replenishing Glucose and Glycogen) in muscle. Glucose is is oxidized by the RBC's. |
| What are the characteristics of the Postabsorptive State? | Both Glucose and Fat are used as primary fuel source. Additionally excess AA's are used for energy. We also have Carbon Skeletons in the Pancreas (Alanine, Glycerol and Lactate) which we can convert into Pyruvate which we can use for energy in the TCA Cycle. Lactate is the primary used Carbon Skeleton. Glucose is primarily used to feed the brain. |
| What are the characteristics of the Fasting State? | Most of our energy is from stored fat, however there is also some protein breakdown. When there is no Glucose we feed the brain with Ketones (which can cross the blood brain barrier). A key principle is that fat and glucose metabolism are antagonistic, thus when fat metabolism is high Glucose metabolism is inhibited, thus we spare Glucose. |
| What are the characteristics of the Starvation State? | Major fuel is from Stored fat, we also increase energy production from protein breakdown. The brain is solely reliant on Ketones for energy as there simply is not enough Glucose to feed it. |
| What is Ketogenesis? | Ketogenesis is the creation of Ketones from fat (Acyl-CoA) breakdown to Acetyl CoA through Beta Oxidation. Acetyl-CoA would usually be used for energy in the TCA Cycle, but the key substrate Oxaloacetate is low, thus the cycle cannot run, thus Acetyl-CoA is used to synthesis Ketones. |
| What is the role of AMPK? | AMPK is the bodies fuel sensor, to this end it controls when ATP is Broken down and when it is Synthesized. Thus its role in Metabolism is key. |
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