kidney physiology

let me write it later

https://docdro.id/RYyp7oc

using:
https://www.histology.leeds.ac.uk/urinary/kidney.php
http://fblt.cz/en/skripta/vii-vylucovaci-soustava-a-acidobazicka-rovnovaha/1-funkcni-morfologie-ledvin/
https://www.quora.com/What-is-the-function-of-the-renal-medulla-Where-is-it-located