Resp - Acid Base Flashcards
changes from acidosis
depression of CNS (disorientation, coma)
Kidney eliminates less K (Na reabsorbed w/ secreted H or K) –> hypercalemia –> altered cardiac fxn
changes from alkalosis
overexcitability of nervous system PNS: afferent (pins and needles) efferent (muslce spasms) CNS: extreme nervousness death from resp tetany
sources of H+ in body
CO2*
nutrients (meat –> sulfuric/phosphoric acid)
intermediary metabolism (lactic acid, keto-acids)
buffer systems
bicarb
protein
Hb
phosphate
bicarb buffer
primary ECF buffer vs. non-carbonic acids (HCl)
HCO3»_space;> H+
Use CO2 for H2CO3 in HH eq
protein buffer
primary ICF buffer (also does ECF)
proteins have both acidic and basic groups - great buffers
Hb buffer
primary buffer vs carbonic acid changes
takes H from CO2, keeps out of blood, releases it at lungs to leave as CO2
phosphate buffer
urinary buffer, also does ICF
Na2HPO4 + H NAH2PO4 + Na+
Pick up H in filtrate to maintain gradient so it can be secreted
HH - bicarb buffer
pH = 6.1 + log [HCO3]/[H2CO2] pH = [HCO3]/[CO2] = kidney control/lung control
kidney H+ secretion
based on acidity of blood
H+ out for Na in
no neural/hormonal control
kidney HCO3 secretion
- HCO3 that is in filtrate comes into caps in exchange for H+ (enter tubular cell as H20 and CO2 then enter cap as HCO3)
- if filtered is used up, H combines w/ HPO4 and bicarb (made in tubular cell) enters caps
acidosis renal compensation
up H+ secretion (down plasma H)
reabsorb filtered HCO3 and new HCO3 (up plasma HCO3)
==> up pH
alkalosis renal compensation
down H+ secretion (up plasma H)
incompletely reabsorb filtered HCO3 –> excretion of HCO3 (down plasma HCO3)
==> down pH
urinary buffers and fxn
fxn: keep H+ gradient high to allow secretion
buffers: phosphate (diet) and secreted ammonia
kidney: ammonium excretion
when phosphate buffers are saturated, tubular cells secrete NH3 (from glutamine, controlled by H+)
NH3 + H –> NH4
NH4 is not so permeable –> excreted
