4B- Fed and Fasted States Flashcards
- Describe the general metabolism of glucose, fats, and proteins in the fed state following their absorption from the digestive tract into the following tissues: liver, brain, red blood cell, muscle and adipose tissue.
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What does insulin do in the fed state?
in the fed state, insulin allows glucose uptake into msucle and adipose tissues
muscle uses the glucose to replenish glycogen storage
adipose oxidize glucose for energy and also use glucose as the source of glycerol of triglycerides they store
How are blood glucose levels maintained during a short term fast (up to 12h)?
talk about the pancreas, liver and adipose tissue
2 hours after eating, blood glucose levels drop so the pancreas stops secreting insulin and starts secreting glucagon
the liver starts to degrade its glycogen stores (glycogenolysis) and release glucose into the blood
it also goes through gluconeogenesis by converting noncarbohydrate precursors (lactate, glycerol, and amino acids) into glucose
when insulin drops, glucagon rises and adipose tissues undergo lipolysis which coverts fatty acids into glycerol, which enter the blood.
most of the fatty acids undergo beta-oxidation into acetyl-CoA’s for the
How are blood glucose levels maintained during a prolonged fast (starvation)?
muscle decreases its use of ketone bodies and depends mainly on fatty acids for fuel
liver continues to covert fatty acids into ketone bodies to supply the brain. it also makes free glucose (by guconeogenesis) for RBC’s and a little for the brain.
adipose tissue continues to break down TG’s for FA’s and glycerol for fuel.
Provide a summary of fasting
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Provide a summary of fasting for days
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What metabolic pathways are active in the liver?
gluconeogenesis
glycogenolysis
TCA
glycolysis
glycogen synthesis
beta-oxidation
What metabolic pathways are active in the brain?
glycolysis
TCA
What metabolic pathways are active in the RBC?
only glycolysis
What metabolic pathways are active in the muscle?
TCA
glycolysis
proteolysis
glycogenolysis
glycogen synthesis
What metabolic pathways are active in the adipose tissue?
lipolysis
lipogenesis
What are the 3 ketone bodies?
Ketone bodies are produced from excess acetyl-CoA when fatty acids are broken down, making:
acetone, acetoacetic acid, and beta-hydroxybutyric acid
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Which 2 ketone bodies can be used as energy?
acetoacetate and beta-hydroxybutyrate can be reconverted to acetyl-CoA to produce energy, via the citric acid cycle.