Hb will more readily bind CO2 than O2. How is this helpful?
the unloading of O2 at the tissues supports the binding of CO2 and the unloading of CO2 at the respiratory membrane (via diffusion gradient) supports the binding of O2
How is bicarbonate formed?
CO2 + H2O <-CA-> H2CO3 <--> H+ + HCO3- where CA = carbonic anhydrase
Where is CA found?
in the RBCs, not the plasma
What is the chloride shift?
When bicarb is made, the bicarb ion diffuses out of the cell, but H+ remains in the cell, so Cl- diffuses in to maintain electrical neutrality
How does bicarbonate benefit the plasma?
it acts as a buffer
Why is it important that the bicarbonate equation is reversible?
at the level of the respiratory membrane so CO2 can form and diffuse across the membrane into the alveoli
What is bicarbonate a marker of?
metabolic function in acid-base balance
What is the Haldane effect?
deoxygenation of the blood increases its ability to carry carbon dioxide and oxygenated blood has a reduced capacity for carbon dioxide; this doubles the amount of CO2 picked up at the tissues and doubles the CO2 released at the lungs
What is respiratory acidosis and what is it a consequence of?
blood pH <7.4 and pCO2 >40mmHg; hypoventilation
What does hypoventilation do to the carbonic acid equation?
pushes it towards the left producing more HCO3- and H+
How does the body compensate for chronic respiratory acidosis?
the kidneys preserve more HCO3- and excrete more H+
In what 2 instances might you see respiratory acidosis?
anesthesia and brain stem injuries
What is respiratory alkalosis and what is it a consequence of?
blood pH >7.4 and pCO2 <40mmHg; hyperventilation
How does the body compensate for chronic respiratory alkalosis?
the kidneys preserve more H+ and excrete more HCO3-
What can respiratory alkalosis occur secondary to?
pain or hypoxemia
Which of the following is the major transport form of CO2 in the blood? a) Bicarbonate b) CO2 is not transported in the lungs c) Bound to Hb d) dissolved
Which of the following best describes the Bohr effect? a) Deceased P50 b) Increased O2 offloading at the tissues c) Left shift in the oxyhemoglobin dissociation curve d) Increased Hb affinity for O2
Which of the following is false regarding the consequences of exposure to carbon monoxide? a) Left shift of the oxyHb dissociation curve b) Decreased CaO2 c) Decreased Hb affinity for O2 d) Decreased offloading of O2 at the peripheral tissues
Which of the following best describes a respiratory acidosis? a) PCO2 = 40mmHg; pH = 7.4 b) PCO2 = 60mmHg; pH = 7.4 c) PCO2 = 60mmHg; pH = 7.3 d) PCO2 = 40mmHg; pH = 7.3