Jackson 3

Question 1

Less than——– of the oxygen in the blood is dissolved

Answer 1

2%

Question 2

Dissolved O2 represents what is available to .

Answer 2

diffuse

Question 3

Resting O2 consumption is ——-, and the amount of dissolved O2 in the blood is less than 10% of what is needed to support ——-.

Answer 3

~250 ml/min, basal metabolism

Question 4

Therefore, must rely on O2 bound to hemoglobin to carry

Answer 4

~98% of the total O2 in the blood.

Question 5

Hemoglobin is a respiratory pigment found in mammalian erythrocytes
predominant protein in erythrocytes; estimates of

Answer 5

250-280 million Hb molecules per cell

Question 6

Hemoglobin: structure

Answer 6

tetrameric molecule – 4 protein subunits, each with a heme group that includes 1 iron atom that can reversibly bind O2

Question 7

Oxygen carrying capacity of hemoglobin

each subunit can bind an

Answer 7

O2 or not; maximum per molecule of Hb is 4 O2

Question 8

Carrying capacity (saturation) is reached with maximum

Answer 8

HbO2

% saturation= % of Hb in HbO2

Question 9

Total O2 in blood is a function of

Answer 9

PO2 and amount of Hb in blood

Question 10

Binding of O2 to Hb changes the ——- of the Hb molecule, but not the oxygen molecule.

Answer 10

conformation

Question 11

Hb exhibits

Answer 11

cooperative binding of O2

Question 12

3Other substances in the blood can also affect Hb’s affinity for O2. For example, binding of======= Hb binding of O2.

Answer 12

2,3 DPG (see figure at right), reduces

Question 13

Oxygen-hemoglobin dissociation (association?) curve describes the effect of

Answer 13

PO2 on Hb saturation

Question 14

Oxygen-hemoglobin dissociation (association?) curve has

Answer 14

2 possible y axis.

Question 15

O2 content – total

Answer 15

O2 per ml of blood

Question 16

Two regions of the curve describe O2 binding to Hb as a function of

Answer 16

PO2 or the amount of dissolved O2.

Question 17

Oxygen-heme dissociation curve; Plateau region –

Answer 17

loading phase

Question 18

Oxygen-heme dissociation curve: Steep region –

Answer 18

unloading phase

Question 19

Oxygen-heme dissociation curve: P50 is the PO2 at which

Answer 19

½ of Hb is saturated (green line)

Question 20

Oxygen-heme dissociation curve: Note that the amount of dissolved O2 (red line) changes very little as

Answer 20

PO2 increases.

Question 21

PO2 is a measure of dissolved O2 and ——– can diffuse into tissues. It is critical to maintain a pool of dissolved O2 to supply ———–

Answer 21

ONLY dissolved O2

mitochondrial demand.

Question 22

O2 bound to Hb can not diffuse, but O2 is released from Hb into the dissolved pool when —— falls, as it does when O2 diffuses out of the blood into interstitial fluid.

Answer 22

PO2

Question 23

Changes in Hb affinity have different consequences in plateau and steep phase of curve
increase Hb affinity for O2—–>

Answer 23

shift curve to left and Hb is saturated at a lower PO2

Question 24

Changes in Hb affinity have different consequences in plateau and steep phase of curve

decrease Hb affinity for O2 —->

Answer 24

shift curve to right and Hb is less saturated for a given PO2

Question 25

Hb affinity decreased by factors associated with

Answer 25

metabolic activity – curve shifts right

Question 26

increased T due to production of

Answer 26

metabolic heat

Question 27

increased CO2 (Bohr effect) –

Answer 27

CO2 binds to globin part of Hb (allosteric effect)

Question 28

increased H+ (or decrease pH) – H+ also binds to

Answer 28

globin part of Hb and has an allosteric effect

Question 29

increased 2,3 diphosphoglycerate (2,3,DPG) – 2,3 DPG is a product of ——- in erythrocytes that enhances ——–

Answer 29

glycolysis,

offloading/dissociation of O2 by allosteric modulation

Question 30

Remember, exercising muscle is warm, acidic, and produces much

Answer 30

DPG

Question 31

Hypoxic disorders or disorders affecting O2 content
It is important to consider total oxygen content in the blood when interpreting consequences of a disorder. Normal arterial values:

Answer 31

15 g Hb and 20 ml of O2 /100 ml blood

Question 32

Anemia does not change

Answer 32

arterial PO2 or Hb saturation (?) but total O2 content is reduced

Question 33

CO replaces O2 on Hb – competes for binding sites on Hb; forms

Answer 33

carboxyhemoglobin

Question 34

Hb affinity for CO ——- greater than for O2

Answer 34

200-fold

Question 35

according to Vander, CO also shifts Hb-O2 dissociation curve to the

Answer 35

left (binding of CO will increase Hb’s affinity for whatever O2 is has).

Question 36

CO2 transported in 3 forms

Answer 36

dissolved (7%)
bound to Hb (~23%)
as HCO3- (70%)

Question 37

CO2 is more soluble in plasma than

Answer 37

O2

Question 38

CO2 binds to globin portion of Hb – forms

Answer 38

carbaminohemoglobin

Question 39

CO2 has no ——— for O2 binding sites (O2 binds to heme portion)

Answer 39

direct competition

Question 40

Carbonic anhydrase (CA) is the enzyme that catalyzes the formation of ———. CA is found in ——–. Erythrocytes have a ————-.

Answer 40

carbonic acid. CA
eythrocytes (not plasma);
HCO3- / Cl- transporter that moves HCO3- into plasma as it forms (see figure below).

Question 41

The CA reaction —– the plasma.

Answer 41

acidifies

Question 42

Some CO2 converted to —— which is transported into plasma

Answer 42

bicarbonate

Question 43

Carbonic acid reaction reverses which

Answer 43

maintains CO2 gradient into alveolar air.

Question 44

H+ binds to ———- on Hb, but affinity depends on —–

Answer 44

histidine residues, PO2

Question 45

oxyHb affinity for H+

Answer 45

low –

Question 46

deoxyHb affinity for H+

Answer 46

high –

Question 47

so in the tissues, Hb picks up H+ and minimizes effect of

Answer 47

HCO3- on pH

Question 48

then in the lung, Hb releases

Answer 48

H+ to combine with HCO3- and CA reaction runs in reverse

Question 49

Hb buffers most of the H+ produced by the

Answer 49

CA reaction

Question 50

Respiratory alkalosis:

Respiratory rate

Answer 50

faster than normal or hyperventilation results in decreases in
[H+] and PCO2

Question 51

breath-holding is extreme

Answer 51

hypoventilation

Question 52

Respiratory acidosis

Answer 52

Respiratory rate lower than normal or hypoventilation results in increases in
PCO2 and [H+]