Acid Base Flashcards
which dissociate more: strong or weak acids
strong
what is a volatile acid
CO2. H2CO3. can be removed from body by ventilation
what is the other type of acid in the body
fixed acids, or nonvolatile
sulfuric, phosphoric etc
majority of the acid in our bodies comes from what
oxidative metabolism
CO2+H2O–>H2CO3–> H+ HCO3-
What are the 3 lines of defense against pH changes in the body
chemical buffers
respiration
kidneys
what is the main chemical buffer in the body
HCO3
what type of acids do the kidneys excrete
nonvolatile
what is the first line defense against an increase in H+
RBC taking it up and bind with Hb
why is the bicarb buffer system so powerful
HCO3 and CO2 are abundant
readily adjusted by respiration and renal function
Describe the response of bicarb to a strong acid addition
HCO3 binds some CO2
remove excess CO2 via respiration
kidneys add new HCO3 and excrete H
What happens when the renal system has excess acid
all of filtered HCO3 is reabsorbed and additional H is secreted as NH4
what is the renal response to excess base
incomplete reabsorption of filtered HCO3
decreased H secretion
secretion of HCO3 in collecting duct
H+ excess is excreted in which two ways
titratable acid–> conjugate bases like phosphate, urate and creatinine
or as ammonia, joins NH3 in lumen
how do we calculate H excretion
urinary excretion of titratable acid+ ammonium- HCO3
where in the nephron is hte urine most acidic
in collecting duct
What cells secrete H+ and HCO3 in collecting duct
alpha intercalated secrete H via H ATPase, also exchanges for a K+ to maintain charge
beta intercalated secrete HCO3 while reabsorbing Cl
most of H secreted in proximal tubule serves what purpose
to reabsorb filtered HCO3
does the pH change much in proximal tubule
no because majority H secreted binds HCO3 for reuptake
reabsorption of HCO3 ultimately depends on what
the Na K ATPase to cause Na gradient for Na/H exchanger
How are the kinetics set up for reabsorption of HCO3
saturable
where does the NH4 excreted in urine come from
break down of glutamine that yields two NH4 and 2 HCO3 ultimately
why do we increase NH4 in chronic acidemia
because will be excreted and also produces 2 HCO3 with it
What factors control H secretion in renal system
intracellular pH (lower pH higher excretion) plasma pCO2( highger pCO2 higher excretion) inhibiting carbonic anydrase leads to metabolic acidosis increased Na reabsorption increases H secretion(volume changes) increase EC K levels decrease excretion of H increase aldosterone, increase H excretion
describe the connection of diuretic abuse to alkalemia
RAAS system to increase aldosterone which stim K /H secretion and also diuretics cause K depletion leading to tubular secretion of H
all bicarb is reabsorbed
