Acid-Base Balance

Question 1

Buffer

Answer 1

combination of a weak acid or weak base and its salt

resists pH changes

Question 2

Acidosis

Answer 2

pH < 7.35

describes the process that leads to an decreased blood pH

Question 3

Acidemia

Answer 3

describes the state of low blood pH

Question 4

compensation vs correction

Answer 4

compensation, a metabolic or respiratory change outside of the normal range to compensate for acidosis or alkalosis
correction is intervening action to return the blood pH to the proper range

Question 5

Oxidative Metabolism

Answer 5

uses O2 at the mitochondrial level to metabolize nutrients and turn them into ATP & waste products

Question 6

normal blood range pH

Answer 6

7.34- 7.44

Question 7

If H+ was not regulated the acid environment would damage:

Answer 7

metabolic processes
alter consciousness
increase neuromuscular irritability
coma, death

Question 8

Buffer systems (4)

Answer 8

bicarbonate-carbonic acid buffer
hemoglobin buffer system
proteins as buffers of H+ (usually only in cells)
phophate buffer - only for the kidneys

Question 9

Major organs involved in acid-base maintenance

Answer 9

Kidney & Lungs

Question 10

Bicarb-Carbonic Acid Buffer general characteristics

Answer 10

h2co3 dissociates into co2 & h20 allowing co2 to be eliminated by lungs & H+ to leave as water through the kidneys

Question 11

correction to bicarb-carbonic acid system

Answer 11

changes in co2 modify the ventilation rate of the lungs

Question 12

compensation of bicarb-carbonic acid system

Answer 12

hco3- concentration can be altered by the kidneys

this system also binds H+ when it appears

Question 13

Bicarbonate- carbonic acid buffer system equation

Answer 13

co2 + h2o h2co3 H+ + hco3-

reaction is reversible

Question 14

formula to calculate carbonic acid

Answer 14

pCO2 x 0.0307

Question 15

tCO2 component

Answer 15

carbonic acid + bicarbonate (90%)

Question 16

carbonic acid molecular formula

Answer 16

H2CO3

Question 17

bicarbonate ion molecular formula

Answer 17

HCO3-

Question 18

pH calculation

Answer 18

pKa + log salt/acid
pKa - always use 6.1 during these calculations
acid- carbonic acid
salt - bicarbonate
normal ratio is around 20/1

Question 19

pCO2 range interpretation

Answer 19

respiratory associated
range 35-45 mmHg
lower than range = alkaline
higher than range = acidosis

Question 20

tCO2 range interpretation

Answer 20

metabolic associated
range 23-29 mmol/L
lower than range = acidosis (loss of bicarb ion)
higher than range = alkaline (increase of bicarb ion)

Question 21

Lung involvement

Answer 21

exhale co2, inhale o2
1st line of defense for acid-base disorders
quick effect on acid-base

Question 22

Kidney involvement

Answer 22

reclaims hco3-
produces more hco3- if needed & takes several days to correct a hco3- deficiency
long term compensation

Question 23

factors affecting increased levels hco3-

Answer 23

when hco3- is increased we excrete hco3-

retain it when compensating lung disease & when cl- loss exceeds what is needed for electrical neutrality

Question 24

factors affecting decreased levels of hco3-

Answer 24

diuretics
reduced absorption when there is loss of cations
when kidney is not functioning (nephritis, infections)

Question 25

Acid-base disorders

Answer 25

respiratory acidosis respiratory alkalosis metabolic acidosis metabolic alkalosis

Question 26

metabolic acidosis (non respiratory )

Answer 26

decreased hco3- ( bicarb ion) increase in acids= ketoacidosis decrease in acid excretion= renal tubular acidosis, diarrhea, loss of bicarb ion

Question 27

respiratory acidosis

Answer 27

``` increased pCO2 ( increase in carbonic acid bc lungs cant get rid of co2) COPD: chronic obstructive pulmonary disease, hypoventilation CHF ```

Question 28

most common causes of metabolic acidosis

Answer 28

ketoacidosis, shock, severe diarrhea, impaired kidney function

Question 29

metabolic alkalosis

Answer 29

increased hco3- (bicarb ion) ingestion of bicarb producing salts disease: diuretic therapy, vomiting, nasogastric suction

Question 30

respiratory alkalosis

Answer 30

decreased pCO2 more common missing H+ hypoxia from drugs like salicylates or increased temp due to fever, hysteria, pulmonary embolism, pulmonary fibrosis breathing into paper bag to correct - increase lvl of carbonic acid by breathing co2 rich air

Question 31

Oxygen transport

Answer 31

transported by hemoglobin sigmoidal curve due to affinity of o2 & hem after 1 o2 attaches, the affinity for other o2 is increased & same in the reverse see release of o2 when po2 is 60 mmHg or less

Question 32

oxygen at lung level is influenced by :

Answer 32

``` alveolar destruction pulmonary edema airway blockages inadequate blood supply rate of diffusion of co2 from blood & diffusion rate of o2 out of lung ```

Question 33

oxygen transport in hemoglobin is influenced by :

Answer 33

``` [co] pH temp of blood [pco2] 2,3 DPG in RBC presence of non-functioning hemoglobin ```

Question 34

left shift in o2 saturation curve

Answer 34

^ o2 saturation & v pco2 | ^ pH ( v H+), v 2,3 DPG, v temp

Question 35

right shift in o2 saturation curve

Answer 35

v o2 saturation % ^pco2 | ^ pH (^H+), ^ 2,3 DPG, ^ temp

Question 36

if a sample is not on ice what will be increased?

Answer 36

pCO2

Question 37

if a sample is correctly & anaerobically collected but is not processed immediately what will be abnormal?

Answer 37

incrased p02 from the leching of hemoglobin

Question 38

low end of pco2

Answer 38

respiratory alkaline loss of carbonic acid v h2co3

Question 39

high end of pco2

Answer 39

respiratory acidosis increase carbonic acid ^ h2co3

Question 40

low end of tco2

Answer 40

metabolic acidosis loss of bicarb ion v hco3-

Question 41

high end of tco2

Answer 41

metabolic alkalosis increase of bicarb ion ^ hco3-

Question 42

Measurements of blood gases

Answer 42

pH potentiometric pCO2: modified pH electrode thatm easures dissolved co2 pO2: amperometrical electrode

Question 43

Errors in electrode measurements

Answer 43

protein build up on the ISE membrane ** bacterial contamination of inner electrode solutions incorrect calibration of the ISE

Question 44

Calibration of blood gas analyzers

Answer 44

always 37 C temp 2 different pH buffer solutions to calibrate 2 gas mixtures to calibrate pCO2 & pO2

Question 45

Specimens for blood gases

Answer 45

``` collected in heparin* placed on ice* collected anaerobically* processed immediately ** otherwise metabolism will continute to occur in the tube & will generate additional H+ & p02 ```