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26 Cards in this Set
- Front
- Back
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How do SUGARS and AMINO ACIDS get to the liver?
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Through the PORTAL BLOOD
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How do FATS get to the liver?
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Fat --> Lymph --> thoracic duct --> systemic blood --> Peripheral tissues --> Liver
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What happens to EXCESS CARBOHYDRATES in the FED STATE?
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Becomes
- GLYCOGEN (liver, muscle) + FAT (adipose) |
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What happens to EXCESS AMINO ACIDS in the FED STATE?
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Becomes MOSTLY FAT (not stored as protein)
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What happens to EXCESS FATS in the FED STATE?
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Becomes STORED FAT (in adipose) (not converted to CBH.
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Fasting state:
GLYCOGEN breakdown? |
Glycogen -> glucose -> CO2 + energy
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Fasting state:
FAT breakdown? |
Fat -> FFA -> acetyl-CoA -> CO2 + energy
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Fasting state:
AMINO ACID breakdown? |
Amino acids -> glucose + ketoacids -> CO2
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What roles do the LIVER play in METABOLISM?
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- Central processing and distributing role
- Feeds other tissues with an appropriate mix of nutrients via the bloodstream |
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3 reasons that energy stores are required?
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1. Fuels are provided at meal time, which are irregular, and not in phase with demand
2. Every organ consumes energy at different rate 3.Need stores to even out nutrient supplies, and for times of need |
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Which fuels yield the most energy?
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Fat (adipose TAG): 141000Kcal
Protein (muscle): 24000Kcal Glycogen (liver): 600Kcal Glycogen (muscle): 300Kcal Glucose (extracellular): 80Kcal |
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In terms of energy, what are the 2 types of tissues?
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Consumers and Maintainers
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What are Consumer Tissues?
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Nett users of energy
(Brain, muscle, excretory organs) |
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What are Maintainer Tissues?
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Regulate, store, release and interconvert energy
(Liver, adipose) |
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What do hepatocytes do to nutrients?
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Transforms them into fuels and precursors needed by other tissues.
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What causes the kinds and quantities of liver-supplied nutrients to vary?
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Diet and time length between meals.
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What determines demand by extra-hepatic tissues?
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Depends on the organ + activty of the organism.
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Explain how the liver has awesome metabolic flexability?
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Liver enzyme levels are mediated by type and balance of diet.
(When the diet is rich in protein hepatocytes contain high levels of enzymes needed for amino acid metabolism and gluconeogenesis. Hours after a switch to a carbohydrate diet the levels of these enzymes drop and more appropriate enzymes are synthesised.) |
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How can the liver's GLUT2 glucose transporter ensure that:
Hepatic glucose conc. = blood glucose conc. |
GLUT2 is insulin-insensitive, so glucose has no directional pressures.
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Fructose, galactose, and mannose are all converted to...
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Glucose.
Unless required for carb structure |
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What are the 5 fates of Glucose-6-Phosphate in liver?
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1. Dephosphorylation to replenish blood glucose.
2. Conversion to liver glycogen. 3. Pentose phosphate pathway to generate NADPH and ribose. → Pyruvate → Acetyl CoA: 4. Oxidation for energy generation via glycolysis and citric acid cycle (& oxidative phosphorylation). 5. Lipid synthesis. |
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What are the 5 fates of Amino Acids in liver?
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1. Liver and plasma protein
synthesis. 2. Released for extrahepatic protein synthesis. 3. Precursors in biosynthesis. 4. Deamination to ketoacids for use in (a) gluconeogenesis, (b) energy production, or (c) lipogenesis. 5. Glucose-alanine cycle. |
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What are the 6 fates of Fatty Acids in liver?
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1. Liver lipid synthesis.
2. Major oxidative fuel for liver. 3. Precursors of ketone bodies. 4. Cholesterol synthesis. 5. Hepatic TAG and phospholipid are exported as lipoproteins. 6. FFA exported on albumin as fuel for heart and muscle. |
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Attributes of Adipose tissue.
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- Amorphous
-Widely distributed - Accounts for 15-25% of young adults |
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Attributes of Adipocytes.
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- High metabolic activity
- Responds to hormonal stimuli - Has active glycolytic metabolism - Uses Citric Acid Cycle to oxidise pyruvate and fatty acids - Can convert glucose to fatty acids (level nowhere as high as liver though) |
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What are O2 consumptions of muscle at rest and when active?
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Rest: ~50% of overall O2 consumption
Active work: 90% of overall O2 consumption |
