Transport of oxygen

Question 1

What are the forms in which oxygen can be transported?

Answer 1

Form 1: Oxygen in physical solution (2%)
Form 2: Oxygen in chemical form (98%)

Question 2

How is oxygen transported in a physical solution?

Form 1

Answer 2

Free oxygen is dissolved in blood

Question 3

Volume and partial pressure of oxygen dissolved in blood

Form 1

Answer 3

V = 0.3ml/100ml, PO2 = 100mmHg in arterial blood
V = 0.13ml/100ml, PO2 = 40mmHg in venous blood

Question 4

What does O2 tension determine?

Form 1

Answer 4

Rate and direction of O2 diffusion
% of hemoglobin saturation

Question 5

How is oxygen transported in the chemical form?

Form 2

Answer 5

Combines with Fe2+ of hemoglobin forming HbO2, HbO4, HbO6 and HbO8

Question 6

What does O2 in the chemical form determine?

Answer 6

The O2 capacity and O2 content

Question 7

What is O2 capacity?

Answer 7

Volume of O2 in ml present in chemical combination with Hb in 100ml blood when Hb is fully saturated

Question 8

How much oxygen can each gram of Hb carry?

Answer 8

1.36 ml of O2

Question 9

What is the general O2 capacity?

Answer 9

O2 capacity = 1.36 x Hb content
= 1.36 x 15g%
=20ml/100ml blood

Question 10

What is O2 content?

Answer 10

Volume of O2 in ml present in chemical combination with Hb in 100ml blood

Not fully saturated

Question 11

O2 content in arterial blood

Answer 11

At PO2 = 100mmHg → O2 content = 19ml/100ml blood

Question 12

O2 content in venous blood

Answer 12

At PO2 = 40mmHg → O2 content = 14ml/100ml blood

Question 13

How is %O2 saturation of Hb calculated?

Answer 13

(O2 content/O2 capacity) x 100

Question 14

%O2 saturation in arterial blood

Answer 14

(19/20) x 100 = 95% or more

Question 15

%O2 saturation in venous blood

Answer 15

(14/20) x 100 = 70%

Question 16

What does the oxygen-hemoglobin dissociation curve represent?

Answer 16

It represents the relationship between partial pressure of O2 (blood PO2) and % Hb saturation (SaO2)

Question 17

Describe the oxygen-hemoglobin dissociation curve

Answer 17

Sigmoid

Question 18

What does the shape of the oxygen-hemoglobin dissociation curve represent?

Answer 18

Saturation of Hb with oxygen varies with partial pressure of oxygen

Question 19

What does the plateau phase of oxygen-hemoglobin dissociation curve represent?

Answer 19

At high partial pressure of oxygen, such as in the lung tissue, oxygen taken up by Hb

Uptake of one O2 facilitates the uptake of further O2

Question 20

What does the sloped phase of the oxygen-hemoglobin dissociation curve represent?

Answer 20

At low partial pressures of oxygen, such as in the tissues of the body, oxygen released to the tissue

Low affinity of Hb to O2

Question 21

What causes the sigmoid shaped oxygen-hemoglobin dissociation curve?

Answer 21

Presence of 4 heme groups in the Hb
Each group can combine to one molecule of O2 and the groups differs in their affinity to O2 as the O2 tension increases

Question 22

What factors cause a rightward shift in the oxygen-hemoglobin dissociation curve?

Answer 22

Increased blood PCO2 (Bohr effect)
Increased concentration of 2,3 DPG
Increased body temperature
Increased blood H+ concentration (decreased blood pH, acidosis)
There is decreased affinity of Hb to O2 leading to increase O2 release to the tissues

Question 23

What factors cause a leftward shift in the oxygen-hemoglobin dissociation curve?

Answer 23

Decreased blood PCO2
Decreased concentration of 2,3 DPG
Decreased body temperature
Decreased blood H+ concentration (increased blood pH, alkalosis)
Hemoglobin F (Fetal Hb)
There is increased affinity of Hb to O2 leading to decrease O2 release to the tissues

Question 24

What is myoglobin?

Answer 24

Iron containing pigment present in skeletal muscle

Question 25

Purpose of myoglobin

Answer 25

Stores O2 in the muscles

Question 26

How many oxygen molecules can each myoglobin bind?

Answer 26

One molecule

Question 27

Describe the shape of the myoglobin dissociation curve

Answer 27

Rectangular hyperbola

Question 28

At what partial pressure is myoglobin saturated?

Answer 28

At tissue level, PO2 = 40mmHg, myoglobin is fully saturated
During muscular exercise, if PO2 < 40mmHg, myoglobin release O2 to the muscles