Lecture 42 Flashcards
(10 cards)
Ammonia is very toxic, especially to the _____. The serum level is regulated around _____microM/L by two key enzymes, _______ and _______ because ______ is a major source of ammonia and ______ is a major sink for ammonia.
CNS 35microM/L GLUTAMINE SYNTHETASE GLUTAMINASE GLUTAMINE GLUTAMATE
The expression of Glutamine synthetase (glutamate to glutamine) and Glutaminase (glutamine to glutamate) is tissue specific. The kidneys, intestines, and periportal hepatocytes produce _______ but not ______ ______. The brain, muscles, and perivenous hepatocytes produce ______ ______ but not ______. This means Periportal hepatocytes are where NH4+ is being captured and processed through the urea cycle.
The kidneys, intestines, and periportal hepatocytes produce GLUTAMINASE but not GLUTAMINE SYNTHETASE. The brain, muscles, and perivenous hepatocytes produce GLUTAMINE SYNTHETASE GLUTAMINASE.
_____ provides a nontoxic storage and transport form of ammonia, and it is generated from the conversion of _____ in a reaction that requires ATP + NH4 and is catalyzed by _____ _____.
GLUTAMINE provides a nontoxic storage and transport form of ammonia, and it is generated from the conversion of GLUTAMATE in a reaction that requires ATP + NH4 and is catalyzed by GLUTAMINE SYNTHETASE.
Formation of Urea takes place in the _____, specifically within ______ hepatocytes, and is the most important disposal route for ammonia.
Formations of Urea takes place in the LIVER, specifically in PERIPORTAL hepatocytes, and is the most important disposal route for ammonia.
The sources of Nitrogen in the Urea cycle are as follows: One molecule of N comes from ____ and the other comes from ______ acid.
One molecule comes from NH3 (ammonia), and the other comes from ASPARTIC ACID.
Carbamoyl Phosphate synthetase I (CPS) has an absolute requirement for N-acetyl _______. CPS catalyzes the first rxn in the urea cycle that combines bicarb and NH4+ (the first source of Nitrogen in the urea cycle) with 2 ___ to form Carbamoyl Phosphate. This takes place in the ______ of periportal hepatocytes. Then, _____ combines with carbamoyl phosphate to form _____, which moves to the _____ of the cell where it’s combined with _____ (the second source of Nitrogen in the urea cycle) to form Arginosuccinate.
N-Acetyl GLUTAMATE ATP Mitochondria Ornithine Citrulline Cytoplasm Aspartate
The Urea cycle is regulated by the activation of N-acetyl glutamate synthetase via the AA ______. This AA is common between the Urea cycle and the _____-NO cycle, as it can be converted directly to _____.
ARGININE. Citrulline Citrulline
CPS 1 deficiency is the most severe cause for ______, whereas _____ deficiency is the most common.
Most sever cause for HYPERAMMONEMIA, whereas OTC deficiency is the most common.
Hyperammonemia can be treated with _________, which is converted to _______, and can shunt glutamine to the urine by binding it, thereby getting rid of ammonia from the body.
It can be treated with PHENYLBUTYRATE, which is converted to PHENYLACETATE, and can shunt glutamine to the urine by binding it.
Overview of the Urea cycle reaction is as follows: _____ + _____ + _____ + 3 _____ + H2O –> ____ + ____
Apartate + NH3 + HCO3 + 3 ATP + H2O –> Urea + Fumarate
