Choudhury CIS Flashcards
Amino Acids in Metabolism- Fed State
Amino acids brought in by digestion Travel to liver - Nitrogen to synthesize proteins --- Particularly albumin --- Amino acids released into blood for other tissues
Carbon converted to glucose, ketone bodies or triacylglycerols
- Stored or travel to other tissues
Amino Acids in Metabolism- fasting state
Amino acids released from protein breakdown
- Some released into blood directly
- Some lose the nitrogen to glutamine or alanine to be shuttled through the blood
- – In the kidney, glutamine delivers ammonia into urine
- – In the liver, alanine and other aa deliver nitrogen for urea
- ——-Carbons are converted into glucose, etc.
Clay-colored stools mean
no bilirubin in the feces
tea colored urine
lacking bilirubin for coloration
clay-colored stools and tea colored urine indicate
blockage - tumor, stones, parasites- of hepatobiliary tract
types of hepatitis related to food
A or E
what should pts with liver issues avoid?
alcohol, NSAIDs, things that can increase hepatotoxicity
Hyper-ammonemia
In adults, caused by liver failure
Toxic effects of ammonia
- Brain swelling due to osmotic imbalance (High ammonia and glutamate in astrocytes)
- Astrocytes produce glutamine (From a-ketoglutarate and ammonia–> Exacerbates osmotic imbalance–> At high enough concentrations, opens mitochondrial permeability transition pore)
Decreases glutamate concentration
- An excitatory neurotransmitter
Glutamate
Central to urea production
Provides the two nitrogens Glutamate
- One in ammonium ion
—– From transamination of other amino acids followed by glutamate dehydrogenase reaction
- One in aspartate
—— Glutamate transaminates oxaloacetate (aspartate’s corresponding a-keto acid) to aspartate
Transamination: Removing the nitrogen
Nitrogen transferred to a-ketoglutarate
- Produces glutamate
The amino acid becomes its corresponding a-keto acid
Transamination: Production of Ammonia
Glutamate is deaminated by glutamate dehydrogenase:
a-ketoglutarate
Ammonium ion (NH4+)
reversible
Other sources of ammonia:
Deamination of other amino acids
Purine nucleotide cycle in brain and muscle
Bacteria in the gut
Glucose/Alanine Cycle
In muscle, glucose is metabolized via glycolysis
- Produces pyruvate
Pyruvate is transaminated by glutamate to
form alanine
Alanine is exported and used as one of two
main nitrogen carriers in the blood
Travels to the liver
transamination reactions
move an amine group.
Glutamine
The other main carrier (of nitrogen)
In somatic cells and liver
Glutamate can accept a second Nitrogen to
form glutamine
In liver:
- Reaction used to prevent any ammonia that escaped urea production from leaving liver
In somatic cells
- Glutamine released into circulation to go to liver
- Glutamine used to produce ammonia for urea cycle
Urea Cycle
In Liver Urea Cycle
Nitrogen enters as ammonium ion or aspartate
In mitochondria
- Ammonium ion is used to form carbamoyl phosphate
- Reacts with ornithine to produce citrulline
- Transported to cytosol
In cytosol
- Aspartate reacts with citrulline
- Arginine is generated
- Arginine is cleaved to release urea and regenerate ornithine