Integration of Metabolism Flashcards
Define homeostasis.
Metabolic condition that is the result of dynamic processes to maintain a constant internal environment despite a changing external environment
Define negative feedback.
Acts to resist any deviation
Define metabolism.
Sum of anabolic and metabolic processes, both act at the same time
Which metabolic process requires E?
Anabolism
Which metabolic process yields E?
Catabolism
Pyruvate -> AA
and TCA -> AA
are only for what?
Nonessential amino acids
Which AA are glucogenic? Ketogenic?
Glucogenic: AA that can make glucose via pyruvate or TCA cycle intermediates
Ketogenic: AA that are degraded to acetyl CoA
What happens during the fed state?
Carbs -> Glucose -> Liver and muscle glycogen OR body fat stores
Fat -> Fatty acids -> body fat stores
Protein -> amino acids -> N lost in urine OR body fat stores
What happens during a short-term fast?
Glycogen in liver -> Glucose -> Energy
Body fat stores -> Fatty acids -> Energy
What happens to glycogen after 24 hours?
Depleted
What promotes protein breakdown?
Glucagon
What are the 4 ways to make E during a long term fast?
1) Body protein -> amino acids -> glucose ->E
2) Body protein -> amino acids -> ketone bodies -> E
3) Body fat -> fatty acids -> ketone bodies -> E
4) Body fat -> fatty acids -> E
What are the 2 ways to produce ketone bodies?
Amino acids -> ketone bodies
Fatty acids -> ketone bodies
What is lost in urine during a long term fast?
N and some ketone bodies lost in urine
Ketone bodies are produced from what in the absence of glucose?
Fatty acid oxidation
How do you form acetoacetate?
Condensation of acetyl CoA and the removal of the CoA to form a compound that is converted to acetoacetate
What can acetoacetate do? What are its downsides?
- Fuel the brain since its water soluble
- BUT acidosis
What does TCA need to keep spinning? What happens if not?
- Pyruvate (3 carbons)
- If not, acetyl coa builds up -> ketone bodies
What cannot produce glucose?
Fatty acids
How can ketone bodies become other ketones?
- Lose a CO2 (acetone)
- May add 2 hydrogens (beta-hydroxybutyrate)
What is the RQ for anabolism, short-term and long-term fast?
Anabolism: RQ = 1 (glucose)
Short-Term: RQ = 0.8 (balance of FA and glucose)
Long-Term: RQ = 0.7 (predominantly fatty acids -> acetyl CoA)
What is a ketogenic diet?
VERY low in CHO to promote fatty acid oxidation in absence of glucose
Ketogenic diets are treatments for what?
Epilepsy in kids
What is glycolysis?
Glycolysis: Glucose to Pyruvate
What can pyruvate be converted to anaeorobically? Aerobically?
Anaerobically (no O): lactate
Aerobically (with O): acetyl CoA
What can be used to make glucose? What can’t?
Can: Pyruvate and lactate
Can’t: acetyl CoA
What happens before an amino acid enters metabolic pathways?
Deamination: nitrogen containing amino group = removed
What do carbohydrates yield? Where does it go?
Yield: glucose
Go: stored as glycogen, some is broken down to pyruvate and acetyl CoA
What does the digestion of fat yield? Where does it go?
Yield: fatty acids and glycerol
Go: some are stored as body fat, others are broken down to acetyl coa
What does the digestion of protein yield? Where does it go?
Yield: amino acids
Used: build body protein, some are broken down to acetyl CoA, while the carbon skeleton of others enters the TCA cycle directly
What can acetyl CoA do?
- Enter the TCA cycle to release energy
- Combine with other molecules of acetyl coa to make body fat
Which nutrients can make acetyl coa?
all of them
What is the main characteristic of the pathway from pyruvate to acetyl CoA?
It is metabolically irreversible
