2.3.2 Oxygen and Carbon Dioxide Transport

Question 1

In what two forms is oxygen transported through the body?

Answer 1

Dissolved in plasma and rbc water

Combined with Hb

Question 2

What is equation for dissolved O₂?

Answer 2

Dissolved O₂ = PO₂ * S

Question 3

What is the solubility constant, S, for O₂?

Answer 3

0.003 mL/dL/mm Hg

Question 4

What is the normal oxygen consumption of the body?

Answer 4

250-300 mL O₂/min

Question 5

How much oxygen can 1 g of Hb hold?

Answer 5

1.34 mL O₂

Question 6

What is the normal amount of Hb (g) in the blood?

Answer 6

15 g of Hb

Question 7

Blood PO2 is determined by what form of oxygen carried in the blood?

Answer 7

The O₂ in the liquid phase (not attached to Hb)

Question 8

What is the equation for O₂ saturation of Hb (%)?

Answer 8

O₂ saturation of Hb (%) = [(HbO2,ml/dl / (Hb, g/dl * 1.34 ml/g)] x 100

Question 9

What is the equation for blood O₂ content?

Answer 9

Blood [O2] content, ml/dl = [0.003 ml/(mmHg x dl) x PO2 (mmHg)] + [Hb] g/dl x 1.34 ml/g x % O2 sat]

Question 10

Calculate and insert the remaining values

Answer 10

Question 11

What is the normal PO2 in the arteries? veins?

Answer 11

PaO2 = 100 mm Hg

PvO2 = 40 mm Hg

Question 12

Draw the oxygen dissociation curve of Hb with O2 saturation on the y-axis

Answer 12

Question 13

What four changes can cause the red shift in the ODC of Hb? blue shift?

Answer 13

When trying to remember the changes that occur to cause the red shift, think of the changes that occur while working out

Question 14

Drawing a variation of the ODC by plotting total blood O2 content vs PO2.

What is different about this curve from the ODC with O2 sat vs PO2?

Answer 14

Because dissolved oxygen is a now factor in the y-axis, the ODC curve will not level off. As PO2 rises, the amount of dissolved O₂ in the blood willl continue to rise.

Question 15

What is the equation for VO₂?

Answer 15

VO2 = Q * C(a-v) O₂

Q, cardiac output

C (a-v) O2, difference in arterial and venous O₂ content

Question 16

What is the equation for oxygen extraction ratio (O₂ER)?

Answer 16

O₂ER- C (a-v) O₂/ CaO₂

Question 17

What are the three ways that CO₂ can be transported?

Answer 17

1. Physical solution. Dissolved CO2, mmol / L = 0.03 mmol/(L x mmHg)* PCO2, mmHg.
2. Hydration of CO2, formation of carbonic acid and dissociation into bicarbonate and hydrogen ions
3. Formation of carbamino compounds with plasma proteins and Hb.

Question 18

Where is most of the bicarbonate produced then stored?

Answer 18

Most of the bicarbonate is produced within the RBC. It is then gets transported out of the RBC via a HCO₃^--Cl^- exchanger and is stored in the plasma.

Question 19

What enzyme plays an important role in the formation of bicarbonic acid from CO₂ and water?

Answer 19

Carbonic Anhydrase

Question 20

Draw the curve for CO2 saturation of Hb. Identify the HbO₂ saturation at venous and arterial PCO2.

Answer 20

Question 21

Draw the curve where arterial and venous blood O2 and CO2 content, in ml/dl, are plotted as a function of the respective partial pressures

Answer 21