question

In what 2 ways is oxygen transported in the blood?

answer

dissolved and bound to Hb

question

What percent of the total oxygen is dissolved in the blood?

answer

3%; for every mmHg of O2, the blood contains 0.003mL O2/100mL of blood

question

What form of oxygen is PaO2 a measure of?

answer

dissolved O2

question

What form of oxygen is PaO2 a measure of?

answer

dissolved O2

question

What is the importance of the dissolved O2?

answer

it drives the concentration gradient of O2 across the respiratory membrane

question

What is a normal PaO2?

answer

100mmHg

question

What is positive cooperativity?

answer

the binding of each successive molecule of O2 induces a conformational change in the Hb and making it easier for the next molecule to bind

question

Approximately how much of the RBCs is Hb?

answer

1/3; if a PCV = 45, the Hb = 15g/dL

question

What is the shape of the oxyhemoglobin dissociation curve?

answer

sigmoidal

question

What is oxyhemoglobin?

answer

Hb bound to O2

question

What is reduced Hb?

answer

unbound Hb

question

At what PO2 is Hb 97% saturated? 75% saturated? 50% saturated?

answer

100mmHg; 40mmHg; 28mmHg

question

Where is Hb normally 97% saturated?

answer

arterial blood

question

Where is Hb normally 75% saturated?

answer

venous blood

question

What will PO2 be if SpO2 is 85%?

answer

estimate! between 40 and 100 (75% and 97% SpO2) so probably about 70mmHg

question

Approximately how much O2 can a normal gram of Hb carry?

answer

1.34mL

question

What is the Oxygen Concentration equation?

answer

CaO2 = (1.34 x Hb x (%sat/100)) + (0.003 x PO2) where:
CaO2 = concentration of oxygen in mL/dL
Hb = hemoglobin concentration in g/dL
PO2 = partial pressure of O2 in blood in mmHg

question

Which part of the oxygen concentration equation denotes the O2 bound to Hb? Which part denotes the dissolved O2?

answer

(1.34 x Hb x (%sat/100)); (0.003 x PO2)

question

What will anemia do to Hb concentration?

answer

decrease it

question

What will polycythemia do to Hb concentration?

answer

increase it

question

What does an SpO2 <95% denote?

answer

hypoxemia

question

What 5 things causes a shift to the right of the O2 Hb dissociation curve?

answer

1) decrease in pH
2) increase in temp
3) increase in RBC 2,3 DPG
4) increase in H+
5) increase in CO2

question

What is the Bohr Effect?

answer

a decrease in Hbs affinity for O2; a shift to the right of the O2 Hb dissociation curve

question

What does the Bohr effect do to a patients P50 value?

answer

increases it

question

How does the Bohr Effect effect tissue offloading?

answer

it increases it

question

What 5 things cause a shift to the left of the O2 Hb dissociation curve?

answer

1) increase in pH
2) decrease in temp
3) decrease in RBC 2,3 DPG
4) decrease in H+
5) decrease in CO2

question

What is 2,3 DPG?

answer

glycolysis intermediate

question

What does a left shift of the O2 Hb dissociation curve indicate? How does this effect tissue offloading?

answer

it indicates an increase in Hbs affinity for O2; this decreases offloading at the tissues

question

What does a left shift do to a patients P50 value?

answer

decreases it

question

What is carboxyhemoglobin?

answer

carbon monoxide bound to hemoglobin

question

Why is CO so toxic?

answer

Hbs affinity for CO is 240x greater than its affinity for O2, therefore with a CO partial pressure of only 0.16mmHg 75% of Hb is bound to CO

question

Which way does CO toxicity shift the O2 Hb dissociation curve?

answer

left which means that there isnt much offloading at the tissues

question

What is a non-invasive way to measure oxygenation? When is this method not recommended?

answer

pulse oximetry; it cant distinguish between oxyhemoglobin and carboxyhemoglobin, and therefore is not recommended for CO toxicity patients

question

What are the 5 main causes of hypoxemia?

answer

1) decreased inspired O2 partial pressure
2) hypoventilation
3) V/Q mismatch
4) right to left shunts
5) diffusion impairment

question

True or False: A left to right anatomic shunt will cause hypoxemia.

answer

False! A right to left shunt will!

question

In what 3 ways is CO2 transported in the blood?

answer

1) dissolved (10%)
2) carbamino compounds (30%)
3) bicarbonate (60%)

question

What is carbaminohemoglobin?

answer

CO2 bound to Hb

question

Hb will more readily bind CO2 than O2. How is this helpful?

answer

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

question

How is bicarbonate formed?

answer

CO2 + H2O ;-CA-; H2CO3 ;/*> H+ + HCO3-
*/ where CA = carbonic anhydrase

question

Where is CA found?

answer

in the RBCs, not the plasma

question

What is the chloride shift?

answer

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

question

How does bicarbonate benefit the plasma?

answer

it acts as a buffer

question

Why is it important that the bicarbonate equation is reversible?

answer

at the level of the respiratory membrane so CO2 can form and diffuse across the membrane into the alveoli

question

What is bicarbonate a marker of?

answer

metabolic function in acid-base balance

question

What is the Haldane effect?

answer

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

question

What is respiratory acidosis and what is it a consequence of?

answer

blood pH ;7.4 and pCO2 ;40mmHg; hypoventilation

question

What does hypoventilation do to the carbonic acid equation?

answer

pushes it towards the left producing more HCO3- and H+

question

How does the body compensate for chronic respiratory acidosis?

answer

the kidneys preserve more HCO3- and excrete more H+

question

In what 2 instances might you see respiratory acidosis?

answer

anesthesia and brain stem injuries

question

What is respiratory alkalosis and what is it a consequence of?

answer

blood pH ;7.4 and pCO2 ;40mmHg; hyperventilation

question

How does the body compensate for chronic respiratory alkalosis?

answer

the kidneys preserve more H+ and excrete more HCO3-

question

What can respiratory alkalosis occur secondary to?

answer

pain or hypoxemia

question

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

answer

a

question

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

answer

b

question

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

answer

c

question

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

answer

c

Oxygen and Carbon Dioxide Transport in the Blood – Flashcards

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