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Biochem-Nitrogenous waste cntd - Coggle Diagram
Biochem-Nitrogenous waste cntd
UREA cycle
Product
Input-ammonium enters into urea cycle
NH4 in urine
Glutamine>Main source of NH4
NH4+ is NB buffering system under pathophysiological conditions
Buffers the proton for excretion-
PO4 & NH4
Key function of aa metabolism in kidney – provide
NH3 to buffer protons in urine
Ammonium production in the Kidney
Amine groups removed from Glutamine are used to buffer the protons>reduce requirement of bicarbonate>reclaimed to buffer blood protons
Glutamine>source of energy for Kidneys
Uric ACid in urine
Enzyme: xanthine oxidase
uric acid derived from break down of purines(part of nucleotides)
HypoXanthine converted to xanthine>xanthine to uric acid
Break down of purine reflects break down of nucleic acid
Problems with uric acid
Uric acid Pka=5.4
>>nucleic acid becomes dissociated>exist in equilibrium with its ionized & non-ionised forms
pH in blood is 7.2>thus uric acid with Pka of 5.4 is ionised at physiologic pH
Ionised Uric acid
-poorly soluble at physiologic pH>
↑[Uric acid]>>crystallizes becoz of poor solubility
Crystallization
noticeable in synovial joints>Esp. Big toe>presents as
Gout
)
Treatment of Gout
Drugs
-
Allopurinol
binds enzyme xanthine oxidase to produce>
alloxanthin
which binds to xanthine oxidase(don't come off)>all the xanthine oxidase becomes occupied with alloxanthin
Modify Diet
-reduce dietary intake of nucleic acid rich foods, e.g liver, fish>instead replace with ea vegetables(↑ Fiber & H20)
All the x.o becomes blocked with alloxanthin>enzyme is degraded> ↑ conc. of allopurinol compared to hypoXanthine& xanthine>
enzyme is inhibited & dies
> so HX in not converted to Xanthine & Xanthine is not converted to uric acid