Flash Notes Miscellaneous - Acid Base Basics

Question 1

what is an acid? acidosis? acidemia?

Answer 1

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

Question 2

what is a base? alkalosis? alkalemia?

Answer 2

base: substance that accepts/binds a proton, alkalosis: process that causes an excess of base, & alkalemia: pH of extracellular fluid is higher than normal

Question 3

what is a buffer? why are they important? what role do they usually play?

Answer 3

compound that can accept or donate a proton - important to minimize pH changes in solutions/tissues, usually a weak acid with their corresponding salts

Question 4

what happens when a strong acid is added to a buffer solution?

Answer 4

protons are donated to/accepted by the weak acid forming a salt & limiting the change in pH

Question 5

what do acids do to litmus paper? what do bases do to a litmus paper?

Answer 5

acids turn it pink/red & base stays or turns blue

Question 6

what are the 2 categories of buffers? which one is used most often in acid/base evaluation?

Answer 6

bicarbonate (HCO3-) major extracellular buffer & everything else (non bicarb) - bicarb

Question 7

T/F: all buffers shift in the same direction as pH because pH & [H+] are inversely related

Answer 7

TRUE

Question 8

how are hydrogen ions measured?

Answer 8

by pH

Question 9

how are pH & H+ related?

Answer 9

inversely related, so if one increases the other decreases

Question 10

what is pH?

Answer 10

approximate measure of the concentration of the hydrogen ion, pH = the negative log (base 10) of [H+]

Question 11

a higher H+ means what to pH?

Answer 11

lower pH

Question 12

what are the 3 mechanisms used to maintain pH homeostasis at 7.4?

Answer 12

1. physiochemical buffering (develops immediately), 2. respiratory compensation (elimination or retention of CO2), & 3. metabolic compensation

Question 13

what is the physiochemical buffering mechanism?

Answer 13

balance of cations/anions always maintained that occurs both intra & extra cellularly that occurs immediately & involves HCO3, proteins (hemoglobin & albumin), & phosphates

Question 14

what is the respiratory compensation mechanism?

Answer 14

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)

Question 15

what is the metabolic compensation mechanism?

Answer 15

elimination or retention of H+/HCO3 by the kidney that begins within hours & is complete in 2-5 days

Question 16

what is an anion gap?

Answer 16

calculation/estimate of the difference between cations/anions in serum/plasma used to evaluate a/b balance & to categorize/identify a metabolic acidosis

Question 17

what are the measured cations & anions used to calculate an anion ap?

Answer 17

cations: sodium & potassium, anions: HCO3 & chloride

Question 18

when there are changes in what ions, the anion gap will increase or decrease?

Answer 18

changes in the unmeasured ions!!!!

Question 19

how is the anion gap calculated?

Answer 19

(Na + K) - (Cl + HCO3) = anion gap (anions - cations)

Question 20

what are some common causes of a high anion gap?

Answer 20

alkalemia, dehydration, hyperalbuminemia

Question 21

what are some common causes of a decreased anion gap?

Answer 21

acidemia, hemodilution, hyperglobulinemia, & hypercalcemia

Question 22

what is the traditional approach to acid/base status?

Answer 22

using the henderson-hasselbalch equation: pH = 6.1 + log [HCO3]/(0.03 X pCO2)

Question 23

what is the non-traditional approach to acid/base status?

Answer 23

strong ion theory

Question 24

what 3 physical laws is the non-traditional approach to acid/base based on?

Answer 24

electroneutrality always maintained, equilibrium equations of incompletely dissociated solutes are satisfied, & conservation of mass

Question 25

what are the 3 independent variables in the non-traditional approach to acid/base?

Answer 25

pCO2, atot (total concentrations of weak acids, balance between strong cations/anions), & strong ion difference

Question 26

what is the strong ion difference? what are the cations? which is the most important cation? what are the anions?

Answer 26

balance between strong cations/anions, cations: Na, K, Mg, Ca, most important is Na (high concentration affects SID), anions: Cl & unmeasured anions (lactate, ketones, sulfates)

Question 27

in the non-traditional approach to acid-base status, an increase in strong ion difference indicates? what about a decrease?

Answer 27

increase = alkalosis & decrease = acidosis

Question 28

what is the one dependent variable used in the non-traditional approach to acid/base?

Answer 28

bicarbonate - altered by internal changes only

Question 29

what is the basic concept of the strong ion therapy?

Answer 29

a/b status is determined by the concentration of CO2, proteins, & anion/cation balance

Question 30

what is partial pressure? what do we measure?

Answer 30

pressure exerted by one compound contained in a mixture, pCO2 (partial pressure of carbon dioxide), pO2 (partial pressure of oxygen), & CO2/O2 are the main blood gases

Question 31

what is the respiratory component in acid/base balance in both approaches to acid/base?

Answer 31

carbon dioxide - end product of metabolism

Question 32

what is the metabolic compenent of acid/base balance which is also the major chemical buffer in the body?

Answer 32

bicarbonate - regulated by the kidneys & indirectly by the lungs

Question 33

HCO3 is regulated by what?

Answer 33

directly the kidneys & indirectly the lungs

Question 34

what is base excess?

Answer 34

net amount of base present

Question 35

what is the base deficit?

Answer 35

net amount of acid present

Question 36

what is negative base excess?

Answer 36

amount of additional acid or base needed to bring pH back to 7.4

Question 37

what is the important equestion to know for bicarbonate?

Answer 37

HCO3 + H = H2CO3 = H2O + increased CO2

Question 38

dogs & cats tend towards what while herbivores tend toward what? why?

Answer 38

dogs/cats: acidemia as HCO3 increases to balance gastric acid secretion & herbivores: alkalemia that is diet related