Lecture 32: O2 and CO2 Transport

Question 1

Two forms in which O2 is carried in the body

Answer 1

1. Dissolved

2. O2 combo with hemoglobin

Question 2

Dissolved O2 percentage

Answer 2

2%

Question 3

Form of O2 that produces partial pressure and drives O2 diffusion

Answer 3

dissolved

Question 4

Does O2 bound to hemoglobin contribute to partial pressure in blood?

Answer 4

Nope

Question 5

When Hb is saturated, blood PO2 rapidly

Answer 5

equalizes with alveolar PO2

Question 6

Hb facilitates a large net transfer of O2 by

Answer 6

acting as a storage depot to keep PO2 low

Question 7

% saturation of hemoglobin is a function of

Answer 7

the PO2 of the blood

Question 8

Binding of O2 to Hb is cooperate, meaning

Answer 8

• The binding of each O2 makes it easier for the next O2 to bind
• This steepens the O2-Hemoglobin Dissociation curve

Question 9

O2 hemoglobin dissociation curve flattens when

Answer 9

Between 60 and 100mmHg as all binding sites become occupied. Occurs in the lungs

Question 10

In a resting individual, the normal PO2 leaving the tissue capillaries of skeletal muscle is about __ mmHg and approx. ___% saturated, meaning…

Answer 10

40
75
some O2 bound to Hb is released into the blood and can diffuse into the tissue

Question 11

During conditions of vigorous exercise, the blood PO2 can decline to levels as low as ___ mmHg because

Answer 11

20

skeletal muscle cells are using O2 in aerobic respiration

Question 12

At PO2 of 20 mmHg, approx. ____% of Hb is saturated with O2. Thus

Answer 12

35%

Hb releases a large amount of O2 to active cells

Question 13

When O2 needs of tissues increase, the blood Po2

Answer 13

decreases

Question 14

P50

Answer 14

• PO2 when Hb is 50% saturated
• Approx 25-35 mmHg
• Used as an indicator for a change in affinity of Hb for O2

Question 15

Effect of CO2 on binding of HB and O2 - increase in metabolic activity in tissues

Answer 15

1. Increase in CO2
2. Increase in H+
3. Decreased affinity for O2
4. Shift of O2 hemoglobin curve to the right

Question 16

Consequence of increased P50

Answer 16

-Hemoglobin unloads O2 to the tissues

Question 17

Bohr effect

Answer 17

The effect of PCO2 and pH on the O2-Hemoglobin association curve

Question 18

Effect of CO2 on binding of Hb and O2 - decrease in metabolic activity in the tissue

Answer 18

1. Decrease in CO2 production
2. Decrease in H+
3. Left shift of O2 Hb dissociation curve

Therefore, when the demand for O2 is more tightly bound to hB and less O2 is delivered to tissues

Question 19

Heat is produced by working muscle and the O2 hb dissociation curve shifts to the

Answer 19

right, providing more O2 to the tissues

Question 20

When heat is produced, P50

Answer 20

increases which suggests a decreased affinity of Hb for O2

Question 21

2,3 - diphosphoglycerate

Answer 21

• By product of glycolysis in rbc
• Binds reversibly with Hb and reduces affinity for O2
• Shifts O2-Hb curve to right

Question 22

Production of 2,3 BPG increases under

Answer 22

hypoxic conditions

Question 23

Anemia effect on 2,3 BPG production

Answer 23

Increases production of 2,3 - BPG by rbc to facilitate the delivery of O2 to tissues
P50 increases

Question 24

PCO2, temp, and 2,3 - BPG effect of O2 HB curve

Answer 24

right shift wiith no change in O2 binding capacity

Question 25

CO effect on O2 Hb curve

Answer 25

Causes a left shift of O2 - Hb curve

Decreases O2 binding capacity

Question 26

Co binds to Hb with an affinity that is ___ times greater than O2

Answer 26

250

Question 27

CO + Hb =

Answer 27

Carboxyhemoglobin (COHb)

Question 28

CO reduces O2 binding by ___ %

Answer 28

50%

Question 29

O2 -binding sites not bound to CO have an ____ affinity for O2, thus

Answer 29

increased

P50 decreases, making it more difficult for O2 to be unloaded in the tissues

Question 30

Three forms of Co2 in the blood

Answer 30

1. Dissolved Co2
2. Carbaminohemoglobin
3. Bicarbonate (HCO3-)

Question 31

Dissolved Co2 depends on the

Answer 31

PCO2

Question 32

What percentage of CO2 is dissolved

Answer 32

10%

Question 33

Carbaminohemoglobin

Answer 33

• CO2 binds with globin portion of hemoglobin
• Reduced Hb has a greater affinity for CO2 than HBO
• Unloading of O2 from Hb in tissue capillaries facilitates picking up of CO2 by Hb

Question 34

What percentage of CO2 is carbaminohemoglobin

Answer 34

23%

Question 35

Greatest percentage of CO2 (___) is in what form

Answer 35

70%, Bicarbonate

Question 36

In the lungs, HCO3-

Answer 36

is reconverted to CO2 and expired

Question 37

The direction of the carbonic acid reaction depends mostly on

Answer 37

CO2

Question 38

Where are H+ and HCO-3 formed

Answer 38

In tissue capillaries

Question 39

Haldane effect

Answer 39

• Hemoglobin that has released its O2 binds more readily to CO2 than Hb that has O2 bound to it
• Removal of O2 from Hb increases the ability of Hb to pick up CO2 and CO2- generated H+
• An increase in O2 released from Hb = an incres in CO2 and H+ uptake by hemoglobin

Question 40

At the lungs, CO2 dissolved in plasma

Answer 40

diffuses into the alveoli and is exhaled

Question 41

When blood reaches the pulmonary capillaries,

Answer 41

• deoxyhemoglobin is converted to oxyhemoglobin
• since oxyhemoglobin has a lower affinity for H+ than deoxy, H+ are released within rbc
• Attracts HCO3- from the plasma, which combines with H+ to form carbonic acid

Question 42

Under conditions of lower PCO2, as occurs in the pulmonary capillaries,

Answer 42

carbonic anhydrase catalyzes the conversion of carbonic acid to carbon dioxide and water