Recent comments in /f/askscience

Coomb t1_jay2nm6 wrote

Reply to comment by Historical_Exchange in How is it that objects in equilibrium stay in motion at constant velocity? by KWOOOSH

I'm not sure what you're thinking, but the key difference between Newton's first law and Newton's second law is that Newton's first law tells you that inertia exists, and Newton's second law tells you how much momentum of an object changes when you exert a force on the object. They're not equivalent.

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Apotropaic_Sphinx t1_jay0ge6 wrote

Reply to comment by CrazyisNSFW in Where does nitrogen in urine come from? by Easy-Care-7463

You are absolutely right. I wanted to touch on that but didn't want to get too wordy. Plus other land animals (like birds) have a different solutions for the toxic Ammonia problem.

This is one of those things that can get super complicated the further down you get into the minutia. OP's question was fairly simple so it's basically food+metabolism+liver=Nitrogen in urine.

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MatthewCollins83 t1_jaxzqs8 wrote

Reply to Where does nitrogen in urine come from? by Easy-Care-7463

Nitrogen in urine comes from the breakdown of proteins in the body. When proteins are metabolized, they are broken down into amino acids, and then converted into ammonia through a process called deamination. Ammonia is then further converted into urea, which is excreted in urine. So, essentially, the nitrogen in urine comes from the nitrogen-containing amino acids in the proteins we eat.

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