1. Overview of the flow of nitrogen in the biosphere. Nitrogen, nitrites and nitrates are acted upon by bacteria (nitrogen fixation) and plants and we assimilate these compounds as protein in our diets. Ammonia incorporation in animals occurs through the actions of glutamate dehydrogenase and glutamine synthase. Glutamate plays the central role in mammalian nitrogen flow, serving as both a nitrogen donor and nitrogen acceptor.

6. Simplified Urea Cycle

11. Urea Cycle 2 1 3 4 5

13. Connections b/w Urea Cycle & CAC

16. 4. As KetoGlut ↓, Oxaloacetate ↓ , CAC halts  Absence of aerobic oxidative phosphorylation and TCA cycle activity  Irreparable cell damage and neural cell death ensue. Electron Transport Chain Oxidative Phosphorylation

17. 5. Also, ↑ glutamate leads to glutamine formation by glutamine synthetase. depleting levels of glutamate ↓, which are needed in neural tissue since glutamate is both a neurotransmitter and a precursor for the synthesis of GABA. GABA is chief inhibitory neurotransmitter in the mammalian CNS, it is directly responsible for the regulations of muscle tone in human. Therefore, ↓ glutamate affect energy production + neurotransmission. Neurotoxicity Associated with Ammonia