Physiology 7 Flashcards
What is the equation for pH?
log 1/[H}
What does an acidosis lead to
depression of the CNS
What does an alkalsosis lead to?
overexcitability of the peripheral NS and CNS
Where is the continual addition of H+ from in the body?
carbonic acid formation (CO2); inorganic acids produced during breakdown of nutrients and organic acids from metabloism
What does a buffer system consist of?
a pair of substances- one which can yield free H+ and another which can bind free H+
What is the henderson-hasselbach equation?
pH = pK + log [A-}/[HA]
What is the enzyme that creates carbonic acid from CO2 nad watr?
carbonic anhydrase
How is bicarb reabsorbed in the proximal tubule?
CO2 and H2O diffuse into epithelial cell and then carbonic anhydrase converts them to carbonic acid which dissocaites into bicarb and H+- H+ is secreted whilst bicarb is co-tranposrted with sodium
What are the 2 tubular buffers?
phosphate and ammonia
Where does phosphate come from and why does this limit its job as a buffer?
all dietary, so if there was not enough dietary intake of phosphate then body would not be able to effectively excrete H+
Why do we need tubular buffers?
energy dependent H+ carriers can secrete H+ against a conc. grad until tubular fluid becomes 800x more acidic than plasma- most urinary H+ need to be buffered to allow adequate excretion of H+
How can the amoutn of H+ excreted as phosphoric acid be measured?
as titratable acid- measure amoutn of base needed to make urine pH 7.4
Where does ammonia come from?
is converted by the epithelial cells from glutamine into ammonia, glutamine comes from the liver
How does titrable acid allow us to calculate the amoutn of “new” HCO3- generated?
acid excreted mols equals new bicarb added to blood.
