Kidney Disease and the Urea Cycle Flashcards
What is haemodialysis?
It is a life-saving treatment for kidney failure that uses a machine to filter and clean the blood, removing waste products and excess fluid when the kidneys are unable to so effectively.
Where is urea produced?
In the liver, in the urea cycle
What is the major nitrogenous excretory product?
Urea
What does the urea cycle do?
detoxifies the ammonia (NH4+)
What is the amount of ammonia in the blood?
30 to 60 umol/L
Explain nitrogen balance
The amount of nitrogen ingested is balanced by the excretion of an equivalent amount of nitrogen. About 80% of excreted nitrogen is in
the form of urea.
Ammonia originates in the catabolism of amino acids that are primarily produced by the degradation of proteins – dietary as well as
existing within the cell:
- digestive enzymes
- proteins released by digestion of cells sloughed-off
the walls of the GIT - muscle proteins
- haemoglobin
- intracellular proteins (damaged, unnecessary)
Why does ammonia is toxic, especially for the CNS?
Because it reacts with a-ketoglutarate, thus making it limiting for the TCA cycle = decreased in ATP
Liver damage or metabolic disorders associated
with elevated ammonia can lead to:
tremor, slurred speech, blurred vision, coma and death
Explain Nitrogen removal from amino acids processes:
- Remove amino group
- Take amino group to liver for nitrogen excretion
- Entry into mitochondria
- Prepare nitrogen to enter urea cycle
- Urea cycle
Name the nitrogen carriers:
- Glutamate
- Glutamine
- Alanine
Explain Creatinine:
Produced from creatine
Explain urea cycle disorders:
Urea cycle disorders (UCDs) include a variety of genetic defects in ammonia metabolism in which one of the urea-synthesis passages is defective, leading to hyperammonemia.
