Hey guys
I’m looking at the bicarbonate buffer system for human bioscience in a first year undergrad course and I’ve totally understood the lung side of the equation, but I’m having a bit of trouble with the kidney side of things.
So far my understanding is that the nephrons can excrete excess H+ ions in the urine, whilst reabsorbing bicarbonate back into the circulation from the urine?
Is this all they do? Most of the sources I’m finding tend to be too simplistic or too advanced for my understanding
Thanks!
In: Biology
Our kidneys are these awesome, super complex things. I’m not a nephrologist by any means so I hope I don’t butcher this, but I think this will do for an A&P class.
You pretty much got it already. Our kidneys will either excrete or reabsorb whatever in order to keep us balanced, including our pH! Acid is H+. One way to rid our body of H is by the excretion if ammonia, which is one nitrogen and 3 hydrogen atoms. (A lot of chemistry goes into this.)
So in further detail, sodium is reabsorbed in exchange for H+ in our renal tubules, bicarbonate ions are shunted to peritubular capillaries (little blood vessels next to our nephron.) CO2 then causes the formation of carbonic acid, which dissociates (breaks up) into a bicarbonate ion and a hydrogen ion. The bicarbonate ion passes into the peritubular capillaries and returns to the blood. The hydrogen ion is secreted into the filtrate (filtrate being fluid filtered from our blood,) where it can become part of a new water molecule (H2O) or becomes pee. 😀
I haven’t used this in a while so here is the source I used to brush up. I reworded it a little to make it a bit easier. https://opentextbc.ca/anatomyandphysiology/chapter/26-4-acid-base-balance/
Does that make sense?
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