Acid-Base Physiology Revisited Flashcards
what is electroneutrality?
sum of positive ions = sum of negative ions
what is chemical neutrality?
[H+]=[OH-]
do we exist in chemical neutrality?
no
alkaline
what are the strong ions in mammalian biological fluids?
Na+
Cl-
K+
SO4
lactate or keto acids
what is the strong ion difference (SID)?
sum of all strong cation concentrations minus the sum of all strong anion concentrations
what is the strong ion difference normally in plasma?
+42 mEq/L
what does it mean that the strong ion difference in negative?
strong anions exceed strong cations
solution is acidic
any change in strong ion difference must change both [H+] and [OH-]; therefore ____________________ is an independent variable, while ___________________ are dependent variables
strong ion difference
[H+] and [OH-]
_________ is a new independent variable, and [H+] and [P-] are dependent variables that change when _________ changes
[Ptot]
[Ptot]
is bicarbonate a dependent or independent variable?
dependent: changes when independent variables are manipulated
what are the independent variables?
water dissociation constant (does not change)
strong ion difference
[Ptot]
PCO2
from where do acid base derangements arise?
abnormalities of strong ion difference, proteins, and PCO2
where are therapeutic efforts to correct acid base derangements directed?
correction of strong ion difference and PCO2
what does PCO2 depend on?
respiration
changes occur rapidly
what does the concentration of strong ions depend on?
gastrointestinal absorption and gastrointestinal and renal loss (normal and pathologic)
changes occur over hours
what does an increased strong ion difference cause?
metabolic alkalosis
what are the major weak acids in plasma?
proteins
what does hyperproteinemia cause?
metabolic acidosis
a decrease in total protein in a patient would result in _____________
metabolic alkalosis
how does the kidney lower [H+]?
excretes more [Cl-] than [Na+]
raises strong ion difference
does movement of bicarbonate in or out of plasma or renal tubules alter [H+]?
no
both are dependent variables
why do you give sodium chloride to a patient with metabolic alkalosis?
in metabolic alkalosis: SID increased
sodium chloride: SID 0
will decrease SID in plasma
