LIN Q's [Acids, Bases, and Buffers] Flashcards
what are the 3 important homeostatic regulators of acid-base balance (in the order of response)?
1) chemical buffer systems
2) respiratory mechanism
3) renal mechanism
acid
tends to donate a proton
base
tends to accept a proton
what are the characteristics of chemical buffer systems?
- first to respond
- bicarbonate; phosphate; protein buffer systems
- remove excess acids or bases
- takes < 1 sec (acid/base neutralization & equilibrium shifting)
what are the characteristics of respiratory mechanism?
- 2nd to respond
- takes 1-3 min
- respiratory center involved
- removes carbon dioxide and therefore H2CO3 (carbonic acid)
what are the characteristics of renal mechanism?
- 3rd to respond bu most potent
- takes hours to days
- kidneys remove metabolic acids (Pi, uric & lactic acids, ketone bodies)
what is the Kd of pure water?
1.8 * 10^-16 M
what is Kw of water at 25 degrees C?
1 * 10^-14
strong acid
dissociate completely in solution
weak acid
dissociate to only a limited extent
what is the Ka of an acid?
it is the dissociate constant of an acid; the tendency of the acid to dissociate and donate a H+ ion; equation: Ka= [H+[A-]/[HA]
what is Henderson-Hasselbalch equation?
estimate the pH of a solution of an acid when pKa is known; the pH of a buffer system is controlled by [A-]/[HA]; equation: pH=pKa + log([A-]/[HA])
when does the weak acid tend to dissociate?
when the pH > pKa
Le Chatelier’s Principle
if a dynamic equilibrium is distributed by changing the conditions, the position of equilibrium ives to counteract the change
[HIGH YIELD] what determines plasma pH?
either concentration of bicarbonate or the PaCO2
what is the plasma pH that is maintained by renal and respiratory systems? and what buffer ratio causes this plasma pH?
plasma pH= 7.4 when buffer ratio= 20/1
what would happen if the pH is still low after acid is added in the bicarbonate buffer system?
the H+ will rise and removed by the kidneys.
the HCO3- will be retained by the kidneys.
what are some characteristics of protein buffer system?
- work in both ICF & ECF
- amino groups accept a proton
- carboxyl groups donate a proton
- side chain can be partially deprotonated
protein buffer system: what has histidines?
albumin (in ECF) and Hb (in ICF)
protein buffer system: what are the most important buffer groups of proteins?
imidazole groups of histidine
acidosis and alkalosis is due to imbalance of what?
PaCO2 and [HCO3-]
what causes respiratory acidemia?
decrease in pH due to increase in CO2
what causes respiratory alkalemia?
increase in pH due to decrease in CO2
what causes metabolic alkalemia?
increase in pH due to increase in HCO3-
what causes metabolic academia?
decrease in pH due to decrease in HCO3-
Davenport Diagram
a graphical tool that helps a physician or investigator to diagnose the causes of acidosis and alkalosis; a specific area in the diagram represents a specific disorder
what do the buffer systems in our body control?
changes in [HCO3-] and pH
what are the three buffer systems talked about in class?
1) bicarbonate buffer system
2) phosphate buffer system
3) protein buffer system
phosphate buffer system
- intracellular buffer
- phosphate anion dissociates to generate H+ and the conjugate base, mono hydrogen phosphate with a pKa of 7.2
which diseases lead to metabolic acidosis?
- diabetes
- heart failure
- renal failure
- diarrhea
what can cause metabolic alkalosis?
- vomitting
- ingestions of soda (NaHCO3)
T/R the renal regulator can retain bicarbonate to increase the plasma pH
TRUE
