|
Overview
  •  Nitrogen balance 
    • positive
      • amino acid (AA) intake > excretion
      • examples
        • growth
        • pregnancy
    • negative
      • AA excretion > intake
      • examples
        • kwashiorkor
        • starvation
        • infection
  • AA absorption in intestine
    • proteins degraded by trypsin and pepsin
      • enteropeptidase cleaves trypsinogen (inactive) to trypsin (active)
    • absorbed as AA's across the gut lumen with specific transporter for similar AA's
      • e.g., transporter for basic AA's, transporter for large neutral AA's
    • deficiencies
      • lack of absorption with pancreatitis due to ↓ in degradative enzyme production
      • Hartnup disease
        • defect in large neutral AA transporter in the intestine and renal proximal tubule cells
        • result is a tryptophan deficiency
        • presents similar to pellagra
  • AA absorption in kidney
    • AA's that are filtered from the glomerulus can be actively reabsorbed in the proximal convoluted tubules with similar transporters as the gut
    • deficiencies
      • cystinuria
        • genetic defect in transporter for cysteine, ornithine, lysine, arginine
        • AR
        • presentation
          • cystine staghorn calculi
            • note: cystine = 2x cysteine attached by a disulfide bridge
            • cystine kidney stones result from high concentrations in urine
        • treatment
          • alkalinization of the urine with acetazolamide
 

Please rate topic.

Average 4.8 of 5 Ratings

Questions (1)
EVIDENCE & REFERENCES (4)
Topic COMMENTS (5)
Private Note