Term
| What are the major control points in glycolysis and what are the activators/inhibitors of each? |
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Definition
| 1) Glucose à G6P (hexokinase; - G6P), 2) F6P à F1,6BP (PFK; + F2,6BP, + AMP, - ATP, - Citrate), 3) PEP à Pyr (Pyr kinase; + F1,6BP, - Acetyl-CoA, - ATP, - alanine, - cAMP dependent phosphorylation) |
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Term
| What are the major control points in gluconeogenesis and what are the activators/inhibitors of each? |
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Definition
| 1) Pyr à OAA (Pyr carboxylase; Acetyl CoA), 2) F1,6BP à F6P (F1,6BPhosphatase; - F2,6BP, - AMP), 3) G6P à Glucose (G6Phoshatase; + G6P) |
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Term
| True or false: Glucose can make pyr which makes acetyl CoA, but this reaction can't be run in reverse. |
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Definition
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Term
| True or false: Cholesterol can make acetyl CoA. |
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Definition
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Term
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Definition
| Ketone bodies can make glucose. |
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Term
| What happens to ingested proteins in the fed state? |
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Definition
| Proteins are digested into AA's and absorbed. They are transported to the tissues where they are stored as protein, turned into important compounds, and passed through the TCA cycle for energy. |
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Term
| What happens to ingested fats in the fed state? |
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Definition
| TG's are taken up by chylomicrons and transported to tissues (FA's by LPL). They are stored as fat. |
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Term
| What happens to ingested carbs in the fed state? |
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Definition
| Glucose is taken up and signals an increase in insulin and a decrease in glucagon. Glucose is taken to the brain, RBC's, and muscle where it's metabolized. It's also taken to the liver where it is metabolized, turned into glycogen, and turned into TG via acetyl CoA. VLDL's carry this TG to adipose tissue for storage. Note that adipocytes can also convert glucose to TG on their own. |
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Term
| True or false: The liver utilizes FA's, KB's, AA's, and Glucose as fuels? |
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Definition
| False. The liver cannot use KB's for energy since it doesn't have the enzymes. Note that the liver and the kidney are the only places that can make KB's, though. (The kidney can make them and metabolize them.) |
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Term
| True or false: The brain only utilizes KB's when starved for a prolonged period of time. |
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Definition
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Term
| True or false: Most of our calories come from glucose. |
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Definition
| False. Most of our calories come from FA's. (540: 280 glucose: 80 AA) |
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Term
| What happens to stored fat in the basal state? |
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Definition
| TG is broken down to glycerol (which goes to the liver to be turned into glucose) and FA. FA's go to the liver where they are metabolized. They are also converted to KB's (via Acetyl CoA), which are transported to the muscle. (The brain doesn't need KB's at this point, because it's getting glucose from glycogen stores). |
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Term
| What happens to glycogen in the basal state? |
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Definition
| It's converted to glucose in the liver, which feeds the brain and RBC's. All other bodily functions don't use glycogen. They use fat, protein, and KB's for energy instead. |
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Term
| What happens to protein in the basal state? |
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Definition
| Protein is broken down to AA's which go to the liver to form glucose. Waste products of this pathway are secreted as urea. |
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Term
| True or false: Fat is where we store most of our energy. Glycogen (in both muscle and liver) is second and proteins are third. |
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Definition
| False. We store about 141,000 Cal as fat, 24,000 Cal as proteins, and about 900 Cal as muscle and liver glycogen. |
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Term
| In the fed state, what stimulates the release of LPL from cells? |
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Definition
| Insulin. ApoCII on LP's activates LPL once LPL is bound to the membrane. |
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Term
| How is HSL regulated during fasting? |
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Definition
| Hormone sensitive lipase is activated by protein kinase A (low insulin, high glucagon) and starts breaking down TG's by removing a FA. Other lipases then act, producing FA's and glycerol. In the fed, state, HSL is phosphorylated by an insulin-sensitive phosphorylase. |
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Term
| In the fasting state, proteins are broken down in the muscle into AA's. Some of these pass straight into the bloodstream. What are the partial oxidation products of the TCA that also get sent out after conversion of other AA's and where do they go? |
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Definition
| AA's convert to Alanine and Glutamine in the TCA cycle in muscle cells. Glutamine goes to the kidney to unload an ammonium group before converting to serine or alanine. Glutamine can also convert to alanine in the gut. All alanine goes to the kidney where it is broken down to urea, glucose, and KB's. Recall that alanine is a key AA in gluconeogenesis as it activates protein kinase (+ gluconeogenesis, - glycolysis). |
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Term
| What reactions are seen in the fed state (briefly)? |
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Definition
| Glycogen storage, Glycolysis (high Pyr, high Citrate), TG synthesis, Cholesterol synthesis |
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Term
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Definition
| Activated by F2,6P, AMP during fed state. |
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Term
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Definition
| Activated by Acetyl CoA during the fed state |
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Term
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Definition
| Activated by Citrate during fed state |
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Term
| Carnitine: Palmitoyltransferase I |
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Definition
| Activated when Malonyl CoA (an inhibitor) levels are low in the fasting state. |
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Term
| In the starved state, what fuels the brain? |
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Definition
| KB's produced from FA's in the liver. |
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Term
| How does the body get glucose in the starved state? |
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Definition
| Glycogen supplies have been depleted so glucose needs to come through other means. Glucose comes from both the breakdown of AA's (protein), from glycerol (TG's), and from the lactate being produced by RBC's. Remember that RBC's need glucose in all states. |
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Term
| True or false: during prolonged fasting, muscles get more of their energy from KB's. |
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Definition
| False. Only the brain uses more KB's. The muscles are burning fat while simultaneously breaking down to provide AA's to the liver for breakdown into glucose (RBC's). |
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Term
| True or false: Production of urea goes down during prolonged fasting. |
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Definition
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Term
| When is urea production the highest and why? |
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Definition
| Urea production peaks in fasting state (12 hours). The brain is still using glucose but the only way to get it is by metabolizing protein, so that's what happens. |
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Term
| Outline the steps in the glucose-alanine cycle. |
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Definition
| Ala (from muscle to blood to liver)à Pyr (+NH2 à Urea) à Glucose (from liver to blood to muscle) à Pyr à Ala (gets an NH2 from BCAA's in this last step). |
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Term
| What is ketosis and when is it seen? |
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Definition
| KB's really high in bloodstream. Seen in starvation (normal) and diabetes (out of wack). Above max concentration (70), KB's are excreted in urine. Ketosis also produces metabolic acidosis because the buildup of acetoacetic and B-hydroxybutyric acids exceeds the buffering capacity of the plasma. |
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Term
| Why is there an excess of KB's seen in diabetes? How is diabetes different from the starved state? |
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Definition
| Insulin plays anabolic and inhibitory roles. In diabetes (especially Type I since insulin is gone completely), there is no inhibition of lypolysis so it runs wild. The resulting FA's go on to produce ketone bodies. |
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