Flashcards in Acid-Base Physiology Deck (116)
Acid-base balance is concerned with maintaining?
a normal hydrogen ion concentration in the body fluid
How is normal acid-base balance achieved?
- by utilization of buffers in ECF and ICF
- by respiratory mechanisms that excrete CO2
- by renal mechanisms that reabsorb bicarbonate and secrete hydrogen ions
The hydrogen ion concentration of the body fluids is extremely ____.
As H+ concentration increases, pH _____.
Do equal changes in pH reflect equal changes in H+ concentration? Why or why not?
No, because the relationship between the 2 is logarithmic
What is normal pH range?
7.37 - 7.42
When arterial pH is less than 7.37 it is called what?
When arterial pH is greater than 7.42 it is called what?
What are the 3 mechanisms that contribute to maintaining pH in the normal range?
- buffering of H+ in both ECF and ICF
- respiratory compensation
- renal compensation
Is arterial pH slightly acidic or alkaline?
What are the 2 forms of blood acid?
- CO2 (volatile acid)
- fixed (nonvolatile)
Why is CO2 considered a volatile acid?
Because it easily combines with H2O to form H2CO3 which can then be dissociated into H+ and HCO3 and travel through the blood.
In the lungs it occurs in reverse, CO2 is regenerated and then expired
What results in the production of fixed acid?
Catabolism of proteins and phospholipids
What type of acid is produced when proteins are metabolized?
What type of acid is produced when phospholipids are metabolized?
What are the 7 fixed acids that can be produced in certain pathophysiologic states?
- β-hydroxybutyric acid
- acetoacetic acid
- lactic acid
- formic acid
- salicyclic acid
- glycolic acid
- oxalic acid
Both β-hydroxybutyric acid and acetoacetic acid are produced in what pathology?
When is lactic acid produced?
During strenuous exercise or when the tissues are hypoxic
How are salicyclic acid, glycolic acid, and oxalic acid introduced into the body?
They are ingested
The overproduction or ingestion of fixed acids causes what?
What is the major difference between volatile and nonvolatile acids?
- volatile acids do not have to be buffered
- nonvolatile acids must be buffered in the body fluids until they can be excreted by the kidneys
What is a buffer?
A mixture of a weak acid and its conjugate base or a weak base with its conjugate acid
A buffer solution resists a change in what?
What equation is used to calculate the pH of a buffered solution?
the Henderson-Hasselbalch equation
What is the Henderson-Hasselbalch equation?
pH = pK + log ([A-] / [HA])
What is [A-]?
the concentration of the base form of buffer
What is [HA]?
the concentration of the acid form of buffer
What is pK?
A characteristic value for a buffer pair.
It equals -log of the equilibrium constant (K)
Strong acids (HCl) are more dissociated into H+ and A-, therefore they have ____ equilibrium constants (K) and ____ pKs.