Flashcards in 0610 - Oxygen delivery to the periphery - EG Deck (21):
How does CO2 predominantly travel from the periphery to the lungs?
How does O2 predominantly travel from lungs to periphery?
O2-Hb, small amount dissolved in plasma
Which catabolic pathways consume more O2 than CO2 produced?
fat and amino acid
What causes the sigmoidal shape of the O2-saturation curve of Hb?
initially hard to bind O2, however once O2 is bound, successively easier to bind subsequent O2.
What is the O2 capacity?
~1.35 mL O2/g Hb
roughly how much O2 can be maximally bound to Hb in 1 L of blood?
~200 mL, plus a small amount of dissolved.
What is the rate of O2 consumption at rest?
~250 mL/min (for a cardiac output of 5L)
List the stressors that "right-shift" the Hb-O2 saturation curve.
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
List the stressors that "left-shift" the Hb-O2 saturation curve.
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
What is complex IV of the electron transport chain also known as? (i.e. the name of the protein that consumes O2)
At what location does CO2 occur in mitochondria?
dehydyrogenases (a-ketoglutarate DH; isocitrate DH)
List the various ways CO2 can transport.
(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-)
Are erythrocytes in veins larger or smaller than those in arteries (haematocrit count)?
What is the breakdown (%ages) of the various forms of CO2 transport?
21% as carbamino-Hb; 69% as HCO3-; 10% dissolved CO2
Is carbamino-Hb found in plasma?
No (neglibable (<1%). Just 11% of CO2 in plasma, with 6% dissolved and 5% as bicarbonate.
Is carbamino-Hb found in erythrocytes?
Yes. 89% of CO2 in erythrocyte, with 4% dissolved, 21% carbamino-Hb; 64% as bicarbonate.
What is the function of carbonic anhydrase?
convert CO2 to HCO3-
What is the function of the Cl--HCO3- exchanger of RBCs?
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.
What 3 effects (N) contribute to O2 unbinding in the periphery?
(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.
What is the O2 consumption rate per L?