Test 2 - Acid Base Flashcards
logarithm
compares a ratio instead of an absolute number. Order of magnitude instead of a linear scale
pH
logarithm of the reciprocal of hydrogen-ion concentration in gram atoms per liter
pH
“pH= -log [H+]
pH literall means
potential hydrogen
example, 7.4 to 7.1 is a change of
40-80x
Henderson equation
quantifies relationship between H+, HCO3- and PCO2
Sorensen 1909
introduces log scale as a way of quantifying H+
Henderson-Hasselbalch equation
pH=pKa + log(HCO3/CO2)
Ka and Pka
a= acid, Ka is the value used to describe the tendency of compounds or ions to dissociate. The Ka value is also called the dissociation constant, the ionization constant, and the acid constant.
pKa =
-log10(Ka)
higher the ka
stronger the acid.
acid comes from the latin term
acere, which means sour
acid litmus paper
red
characteristics of bases
slippery, litmus blue,
arrhenius def of acid
releases H+ into solution
bronsted lowry
donating H+ ions
Lewis definition of acid
accept pair of electrons from a base
respiratory acidosis
PCO2 > 45
Metabolic acidosis
HCO3 <22
Acidemia in blood
pH < 7.35
Respiratory alkalosis
PCO2 < 35
Metabolic alkalosis
HCO3 >26
alkalemia
ph > 7.45 in blood
anion gap
Difference between sum of major anions and cations
anion gap equation
(na + k) - (Cl + HCO3)
normal PaO2
75-100mmgh
Partial pressure of CO2
35-45mmhg
bicarbonate levels
22-26mEq/L
Acidity of GI
stomach 1-3, D 6-6.5, J & I 7-8, large int 5-5.7 urine 4.4-8
3 buffers of pH in the body
Body Buffers, Respiratory Control, Renal control
Examples of protein body buffers
intracellular proteins (Hb) are the most effective, extra cellular proteins. Both can accept or donate H+
Phosphate body buffers
intracellular buffer. Also a urinary buffer.
carbonic-acid-bicarbonate buffer
H+ + HCO3- H2CO3 H20 + CO2
Renal vs respiratory compensation
renal works much slower
Causes of respiratory acidosis
MH, adrenal excess, thyroid storm
Metabolic acidosis causes
anion gap(acid gain), non-anion gap(bicarb loss)
Acid gain
lactic acid, keto-acidosis (D type 1, starvation, alcohol associated). Toxic ingestions (methanol, asprin..)
Increase in lactic acid production
shock, seizures, exercise.
Ketoacidosis in Type 1 DM
ketones form when blood levels of insulin is zero
methanol can cause
blindness
ethylene glycol can cause
renal failure
tx of toxic methanol/ethylene
block alcohol dehydrogenase with fomepizole or ethanol
tx of acid gain
charcoal decontamination
how much asprin will kill you
10 to 30g
causes of bicarbinate loss
diarrhea and other intestinal losses, type 2 renal tubular acidosis, carbonic anhydrase inhibitors, ureteral diversion, chronic kidney disease
Toulene found in
gasoline, glue, paint, adhesives
effects of toluene
causes anion gap (hippuric acid). Causes hypovolemia and hypokalemia
renal tubular acidosis
inability to reabsorb bicarb & excrete H+, net retention of HCl, net loss of bicarb
Alkalosis
inability to remove bicarbonate
azolamide
reduces bicarb
rhabdomyolysis
CK released from muscles rises. pH treatment in ureter (5.5) to prevent blockage
Why is the pH of blood 7.35-7.45?
hb is oxygen avid at that range.
