Flashcards in Acid-Base Balance Deck (72)
what is the normal systemic arterial blood pH?
what is considered a basic pH?
greater than 7.4
what is considered an acidic pH?
less than 7.4
the attempt of renal and respiratory mechanisms to reestablish a normal pH
the reestablishment of a normal systemic arterial blood pH, bicarbonate concentration, and carbonic acid concentration
what happens is pH is out of the normal range?
alterations in ion balance
alterations in membrane potentials
changes in the conformation of proteins (enzymes)
which pH range is not compatible with life?
less than 6.8 and greater than 7.8
Acidosis _______ the plasma concentration of calcium. Why?
bc H+ displaces Ca from protein which increases blood Ca
what are the effects of acidosis?
depression of the CNS
coma and death
alkalosis _____ the plasma concentration of Ca.
what are the effects of alkalosis?
hyper-excitability of the CNS
convulsions and death
what are some extracellular buffers?
what are some intracellular buffers?
What would happen with an increase in CO2?
the production of H+ would increase
what is the main driver of respiration?
the need to exhale carbon dioxide
what is a respiratory mechanism for adjusting body pH?
changing rate and depth of breathing
what are the 5 renal/metabolic mechanisms?
1-secretion of hydrogen into the urine and the recovery of bicarbonate from the urine
2-creation of new bicarbonate from the kidney by secretion of H+
3-buffering of secreted H+ by phosphate
4-creating bicarbonate by producing ammonium
5-buffering of H+ by ammonia
explain active secretion of H+ into the urine and recovery of bicarbonate from the urine
the net result of a hydrogen being secreted into the urine is a bicarbonate being recovered from the urine.
how much bicarbonate is usually recovered from the kidneys?
explain the creation of new bicarbonate by primary active secretion of H+
hydrogen is secreted into the urine which increases the H+ concentration which then decreases pH. Because ATP is present, it allows H+ to go against its gradient (keep getting pumped out even though it's concentration is high) new bicarbonate is synthesized rather than uptaken
what is the lowest urine pH?
describe the creation of new bicarbonate through buffering of secreted hydrogen by phosphate
hydrogen pumped into the urine combines with buffers in the urine. the NaHPO4- is converted into NaH2PO4. Bicarbonate can then be synthesized.
what does converting NaHPO4- to NaH2PO4 enable?
we are then able to trap more H+ in the urine and thus produce more bicarbonate
describe creation of new bicarbonate through direct production of ammonium
when arterial blood pH is low, glutamine is converted to ammonium and bicarbonate. the ammonium is transported into the urine which results in an ammonium increase in urine.
describe the production of new bicarbonate through the buffering of ammonia
this occurs in the collecting ducts. we have ATP mediated transport of H+ into the urine which allows it to combine with ammonia and then more can be pumped out. one new bicarbonate ion is synthesized as the result of pumping out one H+.
what is the source of intracellular H+?
anaerobic (non-mitochondrial) metabolism of glucose.
ATP hydrolysis (big source of H+)
excessive formation of ketones
what about the excessive formation of ketones?
it reduces pH
they are produces in the liver by converting acetyl-CoA to ketones which are acidic.
insulin inhibits ketogenesis
how do we correct changes in pH?
occurs almost instantly