Flash Notes Miscellaneous - Acid Base Basics Flashcards
what is an acid? acidosis? acidemia?
acid: substance that gives up/donates a proton, acidosis: process that causes an excess of acid, & acidemia: pH of extracellular fluid is lower than normal, <7.4
what is a base? alkalosis? alkalemia?
base: substance that accepts/binds a proton, alkalosis: process that causes an excess of base, & alkalemia: pH of extracellular fluid is higher than normal
what is a buffer? why are they important? what role do they usually play?
compound that can accept or donate a proton - important to minimize pH changes in solutions/tissues, usually a weak acid with their corresponding salts
what happens when a strong acid is added to a buffer solution?
protons are donated to/accepted by the weak acid forming a salt & limiting the change in pH
what do acids do to litmus paper? what do bases do to a litmus paper?
acids turn it pink/red & base stays or turns blue
what are the 2 categories of buffers? which one is used most often in acid/base evaluation?
bicarbonate (HCO3-) major extracellular buffer & everything else (non bicarb) - bicarb
T/F: all buffers shift in the same direction as pH because pH & [H+] are inversely related
TRUE
how are hydrogen ions measured?
by pH
how are pH & H+ related?
inversely related, so if one increases the other decreases
what is pH?
approximate measure of the concentration of the hydrogen ion, pH = the negative log (base 10) of [H+]
a higher H+ means what to pH?
lower pH
what are the 3 mechanisms used to maintain pH homeostasis at 7.4?
- physiochemical buffering (develops immediately), 2. respiratory compensation (elimination or retention of CO2), & 3. metabolic compensation
what is the physiochemical buffering mechanism?
balance of cations/anions always maintained that occurs both intra & extra cellularly that occurs immediately & involves HCO3, proteins (hemoglobin & albumin), & phosphates
what is the respiratory compensation mechanism?
elimination or retention of CO2 seen within minutes & complete in minutes to hours where CO2 functions as an acid (carbonic acid formed when combined with water & called a volatile acid because removed via the lungs)
what is the metabolic compensation mechanism?
elimination or retention of H+/HCO3 by the kidney that begins within hours & is complete in 2-5 days
what is an anion gap?
calculation/estimate of the difference between cations/anions in serum/plasma used to evaluate a/b balance & to categorize/identify a metabolic acidosis
what are the measured cations & anions used to calculate an anion ap?
cations: sodium & potassium, anions: HCO3 & chloride
when there are changes in what ions, the anion gap will increase or decrease?
changes in the unmeasured ions!!!!
how is the anion gap calculated?
(Na + K) - (Cl + HCO3) = anion gap (anions - cations)
what are some common causes of a high anion gap?
alkalemia, dehydration, hyperalbuminemia
what are some common causes of a decreased anion gap?
acidemia, hemodilution, hyperglobulinemia, & hypercalcemia
what is the traditional approach to acid/base status?
using the henderson-hasselbalch equation: pH = 6.1 + log [HCO3]/(0.03 X pCO2)
what is the non-traditional approach to acid/base status?
strong ion theory
what 3 physical laws is the non-traditional approach to acid/base based on?
electroneutrality always maintained, equilibrium equations of incompletely dissociated solutes are satisfied, & conservation of mass
