Blood Gases Flashcards
Is a substance that can yield a hydrogen ion
(H+) when dissolved in water
Acid
Is a substance that can yield hydroxyl ions (OH-) when dissolved in water
Base
Bronsted-Lowry’s definition of base:
▪ Base is a substance that _________ in the reaction
accepts a proton
Bronsted-Lowry’s definition of acid:
▪ Acid is a substance that can _________ (H+) in the reaction
donate a proton
Unprotonated
acid
Unprotonated
acid
Protonated
base
Relative strengths of acids and bases
dissociation of constant k (value)
Ratio of dissociated ions to the _________
original acid
pH at which the protonated (the base) and unprotonated (the acid) forms are present in equal concentration
pKa
pKa _____ of the ionization constant
negative log
Strong acids has a pKa values of _____
less than 3.0
Raising the pH above the pK will cause it to dissociate and yield a H+ (hydrogen ion)
strong acids
Strong acids dissociates ______
completely
Strong bases has a pKa values of _______
greater than 9.0
Lowering the pH below the pK will cause it to release OH- (hydroxyl ion)
Strong bases
In strong bases ________
Completely dissociate
Dissociates completely
strong acids and bases
Some will dissociated, while others do not
weak acids and bases
It is a combination of a weak acids or weak base and its salt
buffer
main function of buffer
resist changes in pH
first line of defense
Buffer systems
For the buffer system in the intracellular fluid, this includes the ________________________________________
Phosphate buffer system and Protein buffer systems
Plays a role in both plasma and red blood cells
Phosphate buffer
Protein buffer system includes _________
hemoglobin buffer system, amino acid buffers, and plasma protein buffers
Acts as a buffer by transporting hydrogen ions from peripheral tissues to the lungs
hemoglobin buffer system
Most circulating proteins have a net negative charge, which means that proteins are capable of binding with hydrogen ions.
plasma protein buffer
If you have too much _______ inside your body, it would indicate that your blood is acidic, the _______ will now bind with you hydrogen ions to regulate your blood pH
hydrogen ions & proteins
For the buffer system in the extracellular fluid, this includes the ____________________________
Carbonic acid-bicarbonate buffer system and Protein buffer systems
considered as the main buffer system of the extracellular fluid
Carbonic acid bicarbonate buffer system
What are the following organs are the main organs which participate in the regulation of the acid-base status in the body:
lungs & kidney
It is a respiratory component
Lungs
It is a metabolic component
Kidney
When cells in our body metabolize, they release _____________ as a waste product
carbon dioxide
Forced to go inside the cell to maintain electroneutrality
Chloride
What do you call when chloride is forced to go inside the cell to maintain electroneutrality
chloride shift
__________ will accumulate in blood
bicarbonate
______ will combine ____ and result will be your carbonic acid
carbon dioxide (cO2), water (h2O)
Carbonic acid will immediately dissociate to ______________
hydrogen (h+) and bicarbonate (HCO3)
Carbonic acid is accelerated by the enzyme
Carbonic anhydrase
will bind with hemoglobin in the blood circulation
which eventually leads to the lungs
hydrogen ions
hydrogen ions will recombine to your bicarbonate
to form ________
carbonic acid
Carbonic acid will dissociate to ___________________
♦ carbon dioxide will be exhaled from the lungs
carbon dioxide & water
Carbonic acid will dissociate to ___________________
carbon dioxide & water
Carbon dioxide will be exhaled from the _____
lungs
what is the main role of the kidney
retain the bicarbonate
what is the main site which kidney retains the hcO3
proximal convoluted tubule
The carbon dioxide in the plasma will diffuse into the tubule, this will then combine with a water to become
carbonic acid
the enzyme responsible for the production of carbonic acid from carbon dioxide and water is the
carbonic anhydrase
Carbonic acid will dissociate immediately to _______ and _______
hydrogen, bicarbonate
______ will reabsorbed in blood
bicarbonate
Hydrogen ions will go the the lumen of the tubule this will bind to either
monohydrogen phosphate or ammonia
if the hydrogen ion binds with ammonia, its end product would be ______
Ammonium
If the hydrogen ion binds with the monohydrogen
phosphate, the end product would be _______
Dihydrogen phosphate
The end product will be excreted through the ____
urine
Pressure or tension exerted by CO2 gas dissolved in blood
Partial pressure of co2 (pco2)
Normal value of pco2
35-45 mm Hg
Not a measure of CO2 concentration in the blood
pco2
An index of efficiency of gas exchange in the lungs
pco2
→ Total CO2 Content
→ Refers to the total concentration of CO2
in the blood
Total carbon dioxide concentration (tCO2)
Consisting of ionized ____________________________-__ and unionized fraction ________ and physically dissolved_______
(HCO3-, CO3-, carbamino compound)
(H2CO3)
dissolved CO2
Normal value of tco2
23-27 mmol/L
The ______________ in the blood that has been equilibrated with CO2 at __ mm Hg at ______
bicarbonate ion concentration, 40 mm Hg, 37 degrees celsius
Normal value of bicarbonate ion concentration
22-26 mmol/L
The pressure or tension exerted by oxygen gas dissolved in arterial blood which reflects the availability of the gas in blood but not its content
Partial Pressure of O2 (pO2)
Normal value of pO2
80-110 mm Hg
Index of acidity or alkalinity of the blood
pH
pH is _______ to your hydrogen ion cncentration
inversely proportional
more hydrogen ions present in the blood,
the ________, and vice versa
lesser the blood pH
INCREASE = H+
DECREASE = Blood pH
acidic
INCREASE = Blood pH
DECREASE = H+
Alkaline
Acidosis or acidemia pH
< 7.35
Alkalosis or alkalemia pH
> 7.45
process in the body
Akalosis, acidosis
state in blood
alkemia, acidemia
Bicarbonate is ___________________ to the blood pH
directly proportional
related to the acidity of the blood
hydrogen
related to the capacity of the blood to become basic
bicarbonate
Normal value of h+
Normal: 36 – 44 mmol/L (pH 7.34 – 7.44)
Through _______, the body produces much greater quantities of H+
metabolism
The body controls and excretes H+ in order to maintain pH homeostasis through what?
(through regulation by the lungs and excretion by kidneys)
________ will cause alterations in the rates of chemical reactions within the cell and affect the many metabolic processes of the body
Increase H+
Increase H+ can lead to
alterations in consciousness, neuromuscular irritability, tetany, coma, and death
proton acceptor (HCO3-)
A-
proton donor or weak acid (H2CO3)
HA
= the value for the combination of
the solubility constant for pCO2 and the factor to convert mm Hg to mmol/L
0.0307 mmol/L/mm Hg
= pK of HCO3
6.1
= equilibrium between H2CO3 and CO2 in plasma
1:800
proportional to the pCO2
CH2CO3
are measured in blood gas analysis
pH and pCO2
Bicarbonate ion concentration is
calculated parameter
What are measured in parameter
pH, pCO2, pO2
pH
pCO2
HCO3
tCO2
pO2
SO2
O2Hb
7.35-7.45
35-45
22-26
23-27
80-110
>95
>95
pH less than 7.35 – 7.45
Acidemia
Reflects excess base
Alkalemia
Reflects excess acid or H+ concentration
Acidemia
pH greater than 7.35 – 7.45
Alkalemia
when talking about acidosis and alkalosis, it also talks about the ratio bicarbonate and carbonic acid in the blood (as seen in the henderson-hasselbalch equation) what is tha normal ratio
20:1 (bicarbonate:carbonic acid)
Caused by ventilatory dysfunction (a change in pCO2)
Primary respiratory disorder
Resulting from a change in the HCO3 -
ion level
Metabolic (nonrespiratory) disorder
The body tries to restore acid-base homeostasis whenever an imbalance occurs
compensation
If the primary disorder is of metabolic origin, the body will compensate through the ________, and vice versa
respiratory component
if the primary disorder is the respiratory component, then the _______ will compensate
kidney (metabollic origin)
For disturbances of the RESPIRATORY COMPONENT, the kidneys compensate by selectively excreting or reabsorbing anions and cations
Lungs
can compensate immediately, but the response is
short term and often incomplete
Lungs
are slower to respond (2-4 days), however, the
response is long term and potentially complete
kidney
Implies that the pH has returned to the normal range (the 20:1 ratio has been restored)
fully compensated
Implies that the pH is approaching normal
partially compensated
There are times wherein the compensation may return the ratio to ______, but the primary abnormality or disorder is not ______.
normal, corrected
If primary disorder is metabolic origin, the body will compensate through the _____
respiratory component
Decrease in bicarbonate, resulting in a decreased pH as a result of the ratio for the nonrespiratory to respiratory component less than 20:1
Primary Metabolic Disorder Acidosis
pCO2 in primary metabolic acidosis
normal
What are the 4 main acid-base disorder
- Primary Metabolic Acidosis
- Primary Respiratory Acidosis
- Primary Metabolic Alkalosis
- Primary Respiratory Alkalosis
Causes of primary metabolic acidosis compensation
May be caused by the direct administration of an acid producing
substance
● By excessive formation of organic acids as seen with diabetic ketoacidosis and starvation
● Reduced excretion of acids (renal tubular acidosis)
● Excessive loss of bicarbonate from diarrhea or drainage from a biliary, pancreatic, or intestinal fistula
compensation of primary metabolic acidosis
Through hyperventilation, which is an increase in the rate or depth of breathing
● By “blowing off” CO2, the base-to-acid ratio will return toward normal
● Secondary compensation occurs when the “original” organ (kidney) begins to correct the ratio by retaining bicarbonate
Results from a decrease in alveolar ventilation (hypoventilation), causing a decreased elimination of CO2 by the lungs
Primary Respiratory Acidosis
In primary respiratory acidosis pCO2
increases
In primary repspiratory acidosis the bicarbonate to carbonic acid ratio will also ______
decrease
Causes of primary respiratory acidosis
COPD
Bronchopnuemonia
Hypoventilation
Decreased cardiac output
destructive changes in the airways and alveolar walls increase the size of the alveolar air spaces, with the resultant reduction of the lung surface area available for gas exchange
COPD
gas exchange is impeded because of the secretions, WBCs, bacteria, and fibrin in the alveoli
bronchopneumonia
caused by drugs, mechanical obstruction, and asphyxiation, will increase blood pCO2
levels
hypoventilation
less blood presented to the lungs for gas exchange, and therefore, an elevated pCO2
decreased cardiac output
Primary respiratory acidosis compensation
Occurs through nonrespiratory processes
● Kidneys increase the excretion of H+ and increase the reabsorption of HCO3-
● Begins immediately, but it takes days to weeks for maximal compensation to occur
Results from an increased rate of alveolar ventilation causing excessive elimination of carbon dioxide by the lungs
Primary respiratory alkalosis
Results from a gain in HCO3-, causing an increase in the nonrespiratory component and increase in the pH
primary metabolic alkalosis
causes of primary metabolic alkalosis
Results from excess administration of sodium bicarbonate or through ingestion of bicarbonate-producing salts
● Excessive loss of acid
→ Vomiting
→ Nasogastric suctioning
→ Prolong use of diuretics that augment renal excretion of H+
causes of primary metabolic alkalosis
Results from excess administration of sodium bicarbonate or through ingestion of bicarbonate-producing salts
● Excessive loss of acid
→ Vomiting
→ Nasogastric suctioning
→ Prolong use of diuretics that augment renal excretion of H+
compensation of primary metabolic alkalosis
● Depressing the respiratory center
● Hypoventilation increases the retention of carbon dioxide
causes of primary repiratory alkalosis
● Hypoxemia
● Chemical stimulation of the respiratory center by drugs
● Increase in the environmental temperature
● Hysteria, anxiety (hyperventilation)
● Pulmonary emboli
● Pulmonary fibrosis
compensation of of primary respiratory alkalosis
Kidneys excrete HCO3- in the urine and reclaiming H+ to the blood
→ Popular treatment for hysterical hyperventilation: breathing
into a paper bag
▪ when breathing into a paper bag, carbon dioxide cannot
escape and will accumulate in the paper bag, this will then
be inhaled back by the patient with hysterical
hyperventilation.
