This occurs by deamination.

Deamination of amino acids outcomes in the production of ammonia (NH3).

You are watching: The liver quickly combines the ammonia with carbon dioxide to form

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Ammonia is very toxic base and also its accumulation in the human body would quickly be fatal.

However, the liver consists of a mechanism of carrier molecules and enzymes which quickly converts the ammonia (and carbon dioxide) right into urea. This is called the urea cycle.

One turn of the cycle:consumes 2 molecule of ammonia consumes 1 molecule of carbon dioxidecreates 1 molecule the urea ((NH2)2COregenerates a molecule the ornithine for another turn.

Although our bodies cannot tolerate high concentration of urea, it is much less poisonous than ammonia.

Urea is removed properly by the kidneys.

Link to conversation of the anatomy and physiology that the kidneys.

What can go wrong?

There are numerous inherited diseases of the urea cycle led to by mutations in genes encoding one or one more of the necessary enzymes.

The most usual of this is one inherited deficiency the ornithine transcarbamylase, an enzyme required for the switch of ornithine come citrulline. It results in elevated level of ammonia that might be for this reason high regarding be life-threatening.

It is an X-linked disorder; because of this most typically seen in males. It have the right to be cured by a liver transplant.

It can also be caused through a liver transplant! In 1998, an Austrian mrs was provided a new liver indigenous a male cadaver that — unknown come the operated doctor — had a mutation in his single ornithine transcarbamylase gene. The woman"s blood level of ammonia shoot up, and she passed away a few days later.

Uric acid

Humans also excrete a 2nd nitrogenous waste, uric acid. That is the product that nucleic acid, no protein, metabolism. The is created within peroxisomes.

Uric mountain is just slightly soluble in water and easily precipitates out of solution developing needlelike crystals of sodium urate. Thesecontribute come the development of kidney stones;produce the excruciating ache of gout as soon as deposited in the joints.

Curiously, our kidneys reclaim most of the uric mountain filtered at the glomeruli. Why, if that can cause problems?

Uric acid is a potent antioxidant and also thus can protect cells from damage by reactive oxygen species (ROS). The concentration that uric acid is 100-times higher in the cytosol than in the extracellular fluid. So when lethally-damaged cells relax their contents, crystals the uric acid type in the vicinity. These enhance the ability of adjacent dendritic cell to "present" any kind of antigens exit at the exact same time to T cells leading to a stronger immune response. For this reason the threat of kidney stones and gout might be the price us pay for these protections.

Most mammals have actually an enzyme — uricase — for breaking uric mountain down into a dissolve product. However, during the development of great apes and also humans, the gene encoding uricase became inactive. A bias to gout is ours legacy.

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Uric acid is the chief nitrogenous waste of

insectslizards and snakesbirds

(It is the whitish product that birds leave on statues.)

These pets convert the waste assets of protein line — and nucleic acid metabolism — into uric acid.

Because the its low solubility in water, these animals are maybe to eliminate waste nitrogen with tiny loss of water.