o2 gas transport

Question 1

when a gas diffuses into the blood, what is the first thing that happens?

Answer 1

it first dissolves in the plasma

Question 2

why are gas transport mechanisms needed?

Answer 2

bc o2 and co2 are less soluble in plasma than in air

Question 3

do these other mechanisms contribute to the partial pressure of the gas in the blood?

Answer 3

no

Question 4

most o2 that dissolves in plasma is rapidly taken up by what? what is this movement driven by?

Answer 4

red blood cells; partial pressure gradient bw the plasma and ISF.

Question 5

some o2 remains in the ISF but the other 98% binds to what?

Answer 5

hemoglobin (Hb)

Question 6

what does hemoglobin do?

Answer 6

increases the oxygen content of the blood by 50-fold

Question 7

what is oxygen content?

Answer 7

the total o2 present per unit volume

Question 8

each hemoglobin consists of what? what are they called and how many are there?

Answer 8

4 protein subunits; 2 alpha-globin; 2 beta-globin

Question 9

each subunit is bound to what?

Answer 9

heme

Question 10

contains an iron atom that can reversibly bind to one oxygen molecule? this means that each hemoglobin can do what?

Answer 10

heme; bind up to 4 molecules of oxygen

Question 11

binding of o2 to hemoglobin displays what? what does that mean?

Answer 11

cooperativity; as binding sites are occupied by O2, the affinity of the remaining sites will increase

Question 12

a site bound to o2 is said to be _________, and is referred to as _____________.

Answer 12

oxygenated; oxyhemoglobin

Question 13

a site not bound to o2 is said to be _________, and is referred to as _____________.

Answer 13

deoxygenated; deoxyhemoglobin

Question 14

the percentage of o2 binding sites that are oxyhemoglobin depends on what?

Answer 14

the partial pressure of O2 in the blood

Question 15

what is used to visualize the relationship bw Po2 and the oxyhemoglobin percentage?

Answer 15

oxygen-dissociation curve

Question 16

the proportion of binding sites occupied by o2

Answer 16

saturation

Question 17

the percentage of oxygenated binding sites at any given partial pressure

Answer 17

percent saturation

Question 18

what is the percent saturation in the pulmonary veins and systemic arteries? (Po2 = 100mmHg here)

Answer 18

close to 100%

Question 19

what is the percent saturation in the pulmonary arteries and systemic veins? (Po2 = 40mmHg here)

Answer 19

75%

Question 20

the affinity of Hb of O2 _____________ as blood moves thru the pulmonary capillaries, and __________ as blood moves thru the systemic capillaries

Answer 20

increases, decreases

Question 21

increased affinity promotes what? what does that mean?

Answer 21

loading; binding of O2 to Hb

Question 22

decreased affinity promotes what? what does that mean?

Answer 22

unloading; unbinding of O2 from Hb

Question 23

what does a leftward shift in the dissociation curve indicate?

Answer 23

increased affinity that promotes loading

Question 24

what does a rightward shift in the dissociation curve indicate?

Answer 24

decreased affinity that promotes unloading

Question 25

what are factors that affect affinity?

Answer 25

Pco2, pH, temp, 2,3-DPG levels

Question 26

which factors will decrease Hb affinity for O2 and shift the oxygen-dissociation curve to the right? (promoting unloading) where would these conditions be favorable?

Answer 26

increased Pco2, temp, and 2,3-DPG lvls; decreased pH; systemic capillaries where unloading delivers O2 to tissues

Question 27

which factors will increase Hb affinity for O2 and shift the oxygen-dissociation curve to the left? (promoting loading) where would these conditions be favorable?

Answer 27

decreased Pco2, temp, and 2,3-DPG lvls; increased pH; pulmonary capillaries, where loading brings o2 into the blood

Question 28

why does pco2 have a direct effect on O2 affinity? what happens when this occurs?

Answer 28

bc co2 also binds to hemoglobin, when it does it produces a conformational change in Hb that decreases Hb affinity to O2.

Question 29

what happens when Pco2 increases in the systemic capillaries, as co2 moves from ISF to plasma, to red blood cells where it binds to Hb?

Answer 29

decreases Hb affinity to O2, promoting unloading

Question 30

what happens when Pco2 decreases in the pulmonary capillaries, as co2 moves from plasma to alveolar air?

Answer 30

causes co2 to detach from Hb, increasing its affinity of O2, promoting loading

Question 31

how does Pco2 indirectly affect Hb affinity?

Answer 31

by affecting blood pH

Question 32

what does increased Pco2 do to pH?

Answer 32

increase H+ conc, decreasing pH

Question 33

H+ binding causes to Hb causes what?

Answer 33

a conformational change that decreases that affinity of Hb for O2

Question 34

the interaction of Pco2 and pH on the affinity of Hb for O2 is called

Answer 34

the Bohr effect

Question 35

what does increased temp and metabolic activity do?

Answer 35

decreases affinity and increases unloading

Question 36

is produced in red blood cells as a consequence of glycolysis

Answer 36

2,3-DPG

Question 37

what happens when 2,3-DPG binds to Hb?

Answer 37

decrease affinity of Hb for O2 and promote unloading

Question 38

2,3-DPG binds only to deoxyhemoglobin (t or f)

Answer 38

true

Question 39

normally 2,3-DPG has a small effect on Hb affinity but under what conditions does its effect increase?

Answer 39

under low o2 conditions like high altitudes