54: Oxygen Transport

Question 1

Solubility of Oxygen

Answer 1

0.003 ml O2 per 100 ml of plasma

Question 2

[02] dissolved

Answer 2

PO2 (100) x 0.003

Question 3

Blood oxygen content is increased by which oxygen carrier molecule?

Answer 3

Hemoglobin

Question 4

Hemoglobin

Answer 4

tetramer

each monomer has heme group (porphyrin ring with Fe & polypeptide globin)

Question 5

O2 saturation

Answer 5

25, 50, 75, or 100%

Question 6

Saturation

Answer 6

fraction of hemoglobin binding sites that are currently occupied of O2 (%)

Question 7

1 g of hemoglobin

Answer 7

can bind 1.36 ml O2

Question 8

Oxygen content

Answer 8

1.36 x 15 = 20.4

Question 9

Saturation Curve

Answer 9

Sigmoid binding curve

Hill coefficient of 2.8, amount of agonist binding to binding site

Question 10

Why is Hill coefficient of saturation curve not 4?

Answer 10

B/c there’s not complete cooperativity

Question 11

Cooperativity

Answer 11

once one O2 bound to hemoglobin, it’s easier for next one to bind

binding site affinity increased for agonist

Question 12

Hemoglobin relaxed state

Answer 12

high affinity for O2

Question 13

Hemoglobin tense state

Answer 13

low affinity for O2

Question 14

Percent Saturation equatioin

Answer 14

100 x (PO2)^2.8
divided by (P50)^2.8 + (PO2)^2.8

P50: 50% of binding

Question 15

P50 of Oxygen

Answer 15

27mm Hg, 50% Hb binding sites are full

low P50: high affinity

high P50: low affinity

Question 16

Decreased P50

Answer 16

left shift in saturation curve

increased Hb affinity for oxygen

harder to unload oxygen but easier to load oxygen

Question 17

Increased P50

Answer 17

right shift in saturation curve

decrease Hb affinity for oxygen

easier to unload oxygen

Question 18

P50 changes

Answer 18

only minor oxygen loading problems occur if P50 changes since alveolar PO2 is 80-100mm Hg

Question 19

Sigmoid Curve Plateau

Answer 19

Alveolar PO2: loading of O2 good even if alveolar PO2 falls slightly, blood remains well saturated with O2

Question 20

Sigmoid Curve Steep Region

Answer 20

HbO2 at tissues experience drop in PO2, small change in PO2

leads to a large unloading of O2 from Hb

Question 21

Anemia

Answer 21

100% saturation, all binding sites are full

there are less binding sites in total

02 content falls but saturation not affected

Question 22

Anemic patient

Answer 22

has 1/2 the Hb and carries 0.5 times the O2

Question 23

Polycythemia

Answer 23

increase conc of RBC

more Hb per 100 ml of blood

increased oxygen carrying capacity of blood

no change in affinity just more binding sites

opposite of anemia

Question 24

Factors Affecting Hb affinity for O2

Answer 24

ph
PO2
CO
PCO2
temperature
2,3 DPG

Question 25

Working muscle

Answer 25

heats up, produces CO2, acidic temp > ph < CO2 > 2,3 DPG > right shift and P50 > lower affinity for O2 easy unloading

Question 26

pH Bohr effect

Answer 26

``` PCO > pH < rightward shift low affinity easy unloading ```

Question 27

2,3-DPG

Answer 27

synthesis in RBC enhanced by hypoxia, exercise, high altitudes holds Hb in tense state, low affinity, high P50 low O2 affinity, helps unload O2 to tissues feature of chronic hypoxia (COPD, anemia, emphysema)

Question 28

Venous Blood

Answer 28

``` low pH high PCO2 P50 increased rightward shift low O2 affinity ```

Question 29

Carbon Monoxide

Answer 29

high affinity for Hb compete with O2 even at low CO concs. P50 reduced, O2 has greater affinity for O2 harder for Hb to unload the O2 to tissues reduces carrying capacity of Hb for O2 by binding to O2 sites driven off Hb by breathing 100% O2

Question 30

Cooperativity

Answer 30

One O2 site taken up by CO, P50 decreased, O2 unloading reduced