Acid Base Physiology Flashcards
What is the normal blood pH?
~7.4
in the body, what is considered basic and what is considered acidic?
pH > 7.6 is basic
pH
What is the major source of volatile acids?
oxidative metabolism of carbohydrates and triglycerides
what does the oxidative metabolism to produce volatile acids also produce?
CO2 converted to carbonic acid (H2CO3) and back to CO2 to be secreted by lungs
what are two exceptions of oxidative metabolism for volatile acids?
carbohydrate oxidation in hypoxia (lactic acid)
fat oxidation in diabetes mellitus (ketoacids)
what is the chemical reaction that occurs when CO2 and H2O mix?
create H2CO3 that then creates H+ and HCO3
what is the ratio of free H to free HCO3? what does this mean?
1:600000
a shift to the right has a much greater effect on H than HCO3
descrive non volatile acids
excreted by the kidneys
form non carbonic acids, sulfuric, and hydrochloric acids
what molecule do you lose from the following body functions?
1) vomiting
2) diarrhea
3) urine
vomit - H+ loss
diarrhea - HCO3 loss
urine - HCO3 loss
what molecule do you lose from the following body functions?
1) vomiting
2) diarrhea
3) urine
vomit - H+ loss
diarrhea - HCO3 loss
urine - HCO3 loss
what is the difference between volatile and non volatile acids?
volatile metabolism produces CO2 that is excreted by the lungs whereas non-volatile metabolism does not produce CO2 to be excreted in lungs
what is the difference between volatile and non volatile acids?
volatile metabolism produces CO2 that is excreted by the lungs whereas non-volatile metabolism does not produce CO2 to be excreted in lungs
what is the henderson hasselbach equation?
relationship between pH, CO2, and HCO3
pH proportional to concentration of HCO3 and inversely proportional to dissolved CO2
what is the henderson hasselbach equation?
relationship between pH, CO2, and HCO3
pH proportional to concentration of HCO3 and inversely proportional to dissolved CO2
what is the significant of buffers in the body?
acute control of pH and prevent large shifts in pH
what are 2 blood buffers?
plasma
erythrocytes
what kind of buffers does plasma contain?
bicarbonate and phosphate buffers
what kind of buffer does RBCs contain?
bicarbonate buffer
what are 2 tissue buffers?
skeletal muscle
bone
where is a large percentage of the total body HCO3 contained?
skeletal muscle
how does bone offer a buffering system?
large store of carbonate
main source for neutralizing non carbonic acid
what is associated with bone breakdown?
long term non carbonic acidosis
what is associated with bone breakdown?
long term non carbonic acidosis
how does the respiratory system regulate pH
eliminates CO2 from the blood and shift equilibrium away from H2CO3 (and vice versa)
what happens to pH if you incr. or decr. resp rate?
decr RR - decr pH
incr RR - incr pH
what are 3 renal mechanisms for responding to pH changes?
1) bicarbonate reabsorption
2) formation of new bicarbonate/ ammonium:ammonia
3) excretion of hydrogen ions (ammonia/phosphate)
where does bicarbonate reabsorption occur in the kidneys?
proximal tubule mostly
also in collecting ducts
where does bicarbonate reabsorption occur in the kidneys?
proximal tubule mostly
also in collecting ducts
How is HCO3 produced in proximal tubule?
glutamine converted to NH4 and HCO3
what happens to NH4 and HCO3?
HCO3 reabsorbed
NH4 secreted into tubule lumen
what is the ultimate goal of converting glutamine to NH4 and HCO3? where does the HCO3 go?
to put NH3 into the interstitum for later use
HCO3 goes to peritubular plasma
what are the 3 parts to net acid secretion (NAE)? which is most important
UNH4V - urine ammonium excretion (important)
UTAV - titratable acid secretion
UHCO3V - bicarbonate secretion
what is the NAE equation?
NAE = (UNH4V + UTAV) - UHCO3V
what causes little excretion of H from distal tubule?
concentration gradient from plasma to tubule lumen limits amount that can be excreted
which direction does H move in distal tubule? why does this occur?
H moves into tubule
HCO3 buffers the H in tubule lumen
what back up bufferers are in place if all HCO3 is used up?
phosphate and ammonia
what hormone stimulates H secretion?
aldosterone
which buffer is more effective at higher pH?
phosphate
which buffer is more effective at higher pH?
phosphate
what are the 3 responses from the kidney in the case of acidosis? what is the ultimate goal?
goal: incr NAE
1) incr H secretion and incr HCO3 reabsorption to 100%
2) incr NH3 production and loss of NH4
3) generate new HCO3 from glutamine
what are 2 responses from the kidney in the case of alkalosis? what is the ultimate goal?
goal: decrease NAE
1) decr. H secretion
2) decr HCO3 reabsorption
what are 2 responses from the kidney in the case of alkalosis? what is the ultimate goal?
goal: decrease NAE
1) decr. H secretion
2) decr HCO3 reabsorption
how do you determine if someone is acidotic/alkalotic due to respiratory issues or metabolic issues?
if pH is consistent with CO2 or HCO3 levels
CO2 - resp
HCO3 - meta
how do you calculate anion gap?
Na - (HCO3 + Cl)
Na = major extracellular cation
HCO3 and CL = majority of anions associated with Na
what is the anion gap in a normal person?
11mEq/L
what causes metabolic acidosis?
gain of acid through production or ingestion or loss of HCO3 (ex: diarrhea)
what could be causes of increased acid production or ingestion?
prod - lactic/ketoacidosis (diabetes)
ing - methanol, ethanol, aspirin
what happens to the ion gap when HCO3 is depleted? why?
nothing
Cl compensates for loss of HCO3
what is hyperchloremic metabolic acidosis?
loss of HCO3 causes there to be too much Cl in the body but shows a normal anion gap
what are two causes of hyperchloremic metabolic acidosis?
loss of HCO3 from GI tract renal impairment (renal tubular acidosis)(RTA)
what is RTA? what are the 3 different kinds?
RTA - unable to excrete acid load
Type 2 - proximal type (reduced ability to reabsorb HCO3)
Type 1 - distal nephron (late nephron unable to secrete H)
Type 4 - hypoaldosteronism (unable to secrete H)
