Acid-Base Flashcards
Because of its small radius, … is more reactive than other cations in body fluids.
H+
[H+] in plasma is maintained between …
38-42 nEq/L
What are the 3 sources of H+ input into the biological system?
metabolic products (including CO2), dietary intake of acids, and loss of alkali in the GI tract
Metabolism produces a large amount of …, which must be excreted in the expired air.
volatile acid
What two characteristics of CO2 make it a volatile acid?
because it can be removed by ventilation, but has the potential to produce H+ when hydrated
How many moles of volatile acid per day is produced by metabolic activity and removed by ventilation?
15-20 moles
Are volatile acids normally a source of H+?
no
What are 2 sources of a fixed or nonvolatile source of acid?
H+ ingested with foods or in the form of medications
What is the concentration of nonvolatile acid per day?
20 mEq/per day
These ingested H+ cannot be removed from the system by ventilation, thus are …
nonvolatile
Incomplete … during excessive metabolic activity, in the absence of insulin, or during inadequate oxygenation can lead to production of nonvolatile acids like lactic, pyretic, and B-hydroxybutyric acids
glucose and fat metabolism
The net acid/base input for a typical American (Western) diet is usually …
acidic
The loss of base in the form of …., in the stool leaves a net H+ excess in the body
HCO3-
H+ is excreted into the urine as titratable (nonvolatile) acids such as … and as …, part of a buffer system which is unique to the kidneys.
phosphates (HPO4-2/H2PO4-) and as ammonium ion
It is not possible to eliminate the entire daily H+ load in the form of free H+ because urine can only reach pH of 4.5. Therefore, we must employ … in order to remove the normal acid load from the body.
chemical buffers of H+
What diet results in acid production > HCO3- production?
meat-containing diets
What diet results in a net production of alkali in the form of HCO3-, and therefore a net alkaline load and renal excretion of HCO3-?
vegetarian
Hb is an important … buffer.
intracellular
The respiratory system will respond to an acid load. H+ will stimulate … to increase ventilation
peripheral chemoreceptors (carotid bodies)
Is the respiratory control response slow or fast?
fast, occurs within less than a minute, but can be sustained for long periods
The kidneys must excrete an amount of acid equal to the total ….
nonvolatile acid production (which includes normal loss of HCO3- in stool)
The kidneys must replace the…, and prevent the loss of …
HCO3- lost in buffering reactions; filtered HCO3- in the urine
Is the renal response fast or slow?
slow and may take several days for the full response to an acid-base disturbance to be evident
What does the renal system excrete acids as?
H2PO4- and NH4+
What does the Isohydric Principle state?
A change in one buffer pair causes parallel changes in other buffer systems; therefore we can base our analysis on the bicarb system alone.
Since H2CO3 represents the pivot point in the bicarb buffering system adding acid forces the reaction to …
CO2 elimination
Since H2CO3 represents the pivot point in the bicarb buffering system adding alkali (-OH) increases …, which can be eliminated by…
HCO3- (-OH combines with CO2), which can be eliminated by the kidneys or by buffering reactions
In the bicarb buffering system the supply of what is virtually inexhaustible due to metabolic production of CO2?
H2CO3
The Henderson-Hasselbach equation is used to calculate …
how changes in CO2 and HCO3- affect pH
The cellular hydration mechanism produces a … that moves across the apical membrane and a … that moves across the basolateral membrane.
H+; HCO3-
What is the predominant pathway within the proximal RTC for H+ secretion into tubular fluid?
Na+-H+ antiport = NHE3
Where does the energy used to drive NHE3 come from?
Na+-K+ active exchange pump on the basolateral membrane
What is present in the apical membrane of both distal and proximal RTCs that make H+ secretion primary active transport?
H+-ATPase
in the distal RTCs what is the other primary active transport mechanism of H+ secretion?
apical membrane H+-K+ ATPase
The preservation of filtered bicarb is achieved by proximal and distal RTC …
H+ secretion
