0610 - Oxygen delivery to the periphery - EG

Question 1

How does CO2 predominantly travel from the periphery to the lungs?

Answer 1

bicarbonates (~60%)

Question 2

How does O2 predominantly travel from lungs to periphery?

Answer 2

O2-Hb, small amount dissolved in plasma

Question 3

Which catabolic pathways consume more O2 than CO2 produced?

Answer 3

fat and amino acid

Question 4

What causes the sigmoidal shape of the O2-saturation curve of Hb?

Answer 4

initially hard to bind O2, however once O2 is bound, successively easier to bind subsequent O2.

Question 5

What is the O2 capacity?

Answer 5

~1.35 mL O2/g Hb

Question 6

roughly how much O2 can be maximally bound to Hb in 1 L of blood?

Answer 6

~200 mL, plus a small amount of dissolved.

Question 7

What is the rate of O2 consumption at rest?

Answer 7

~250 mL/min (for a cardiac output of 5L)

Question 8

List the stressors that “right-shift” the Hb-O2 saturation curve.

Answer 8

Fast mediators of shift:Increased temperature, decreased pH, increased ppCO2. Factors often consequence of active tissue.Slow mediators of shift:increased 2,3-DPG (takes ~14 days)Increase O2 release from N (50mL/L) to 90 mL/L

Question 9

List the stressors that “left-shift” the Hb-O2 saturation curve.

Answer 9

Fast mediators of shift:decreased temperature, increased pH, decreased ppCO2. Slow mediators of shift:decreased 2,3-DPG (takes ~14 days)Decrease O2 release from N (50mL/L) to 30 mL/L

Question 10

What is complex IV of the electron transport chain also known as? (i.e. the name of the protein that consumes O2)

Answer 10

cytochrome oxidase

Question 11

At what location does CO2 occur in mitochondria?

Answer 11

dehydyrogenases (a-ketoglutarate DH; isocitrate DH)

Question 12

List the various ways CO2 can transport.

Answer 12

(1) CO2 dissolves in plasma. (2) can bind to amino termini of proteins: carbamino-compounds. (3) formation of bicarbonate (water and CO2 to form H2CO3-)

Question 13

Are erythrocytes in veins larger or smaller than those in arteries (haematocrit count)?

Answer 13

larger

Question 14

What is the breakdown (%ages) of the various forms of CO2 transport?

Answer 14

21% as carbamino-Hb; 69% as HCO3-; 10% dissolved CO2

Question 15

Is carbamino-Hb found in plasma?

Answer 15

No (neglibable (<1%). Just 11% of CO2 in plasma, with 6% dissolved and 5% as bicarbonate.

Question 16

Is carbamino-Hb found in erythrocytes?

Answer 16

Yes. 89% of CO2 in erythrocyte, with 4% dissolved, 21% carbamino-Hb; 64% as bicarbonate.

Question 17

What is the function of carbonic anhydrase?

Answer 17

convert CO2 to HCO3-

Question 18

What is the function of the Cl–HCO3- exchanger of RBCs?

Answer 18

export one HCO3- for intake of 1 Cl-. Water follows the influx of Cl-. incoming water also aids formation of HCO3- from CO2. excess H+ from this dislodges O2.

Question 19

What 3 effects (N) contribute to O2 unbinding in the periphery?

Answer 19

(1) decreased ppO2 in local perfused tissues causes Hb to dump O2. (2) drop in pH due to metabolic activity. (3) increased ppCO2 in local tissue, carbamino-Hb formation.

Question 20

What is the O2 consumption rate per L?

Answer 20

~50 mL/min

Question 21

Where is O2 consumed and CO2 produced within a cell?

Answer 21

mitochondria