Human Phys 6.6

Question 1

What percentage of dissolved O2 accounts for total O2 content in the blood?

Answer 1

2%

Question 2

What form of O2 produces a partial pressure?

Answer 2

Dissolved gas

Question 3

What drive diffusion?

Answer 3

Partial pressure

Question 4

What is O2 bound to?

Answer 4

Hemoglobin

Question 5

What percentage does bound gas account for?

Answer 5

98%

Question 6

Does bound gas contribute to partial pressure?

Answer 6

No

Question 7

What does CO2 get modified into?

Answer 7

HCO3 by carbonic anhydrase

Question 8

What is perfusion limited gas exchange limited by?

Answer 8

Amount of blood

Question 9

What is diffusion limited gas exchange limited by?

Answer 9

Strenuous exercise

Emphysema and fibrosis

Question 10

What is the only way to get more diffusion?

Answer 10

Get more blood flow

Question 11

What does pulmonary blood flow determine?

Answer 11

O2 transfer

Question 12

What do both O2 and CO2 bind to for transport?

Answer 12

Hemoglobin

Question 13

Why does O2 reach diffusion equilibrium while CO2 does not?

Answer 13

Hemoglobin in mixed venous blood is already about 75% saturated with O2

Question 14

When does blood become almost fully saturated with oxygen?

Answer 14

By the time it passed through 1/3 of the pulmonary capillary and little additional oxygen normally enters the blood during the later 2/3

Question 15

How long does the blood stay in the lung capillaries to cause full oxygenation?

Answer 15

3x as long

Question 16

How many molecules of O2 can each molecule of hemoglobin bind?

Answer 16

4 molecules of O2

Question 17

What is the PO2 when the arterial blood reaches the peripheral tissues?

Answer 17

95mmHg

Question 18

What is the PO2 in the interstitial fluid that surrounds the tissue cells?

Answer 18

40mmHg

Question 19

What is the % saturation?

Answer 19

Function of PO2 of blood

Question 20

P50

Answer 20

The PO2 at which hemoglobin is 50% saturated

Question 21

What does an increase in P50 indicate?

Answer 21

Drop in affinity

Question 22

What can we tolerate significant drops of PO2 in without significant changes in O2 carried by hemoglobin?

Answer 22

From 100-60mmHg

Question 23

What does a right shift of the O2 hemoglobin dissociation curve mean?

Answer 23

Hemoglobin more likely to let go O2 (low affinity)

Question 24

What does a left shift of the O2 hemoglobin dissociation curve mean?

Answer 24

Hemoglobin hangs on to O2 (high affinity)

Question 25

What causes a right shift in the O2 hemoglobin dissociation curve?

Answer 25

Increase PCO2

Increase temperature

Increase 2.3-DPG

Decrease pH

Question 26

What causes a left shift in the O2 hemoglobin dissociation curve?

Answer 26

Decrease PCO2

Decrease temperature

Decrease 2.3-DPG

Increase pH

Question 27

What is the amount of dissolved CO2?

Answer 27

5%

Question 28

What is the amount of CO2 bound to hemoglobin?

Answer 28

3%

Question 29

What is the amount of CO2 modified to bicarbonate?

Answer 29

90%

Question 30

How much faster can CO2 diffuse than O2?

Answer 30

20x faster

Question 31

What are the pressure differences needed to cause CO2 diffusion?

Answer 31

Much less than those needed to cause O2 diffusion

Question 32

Diffusion of O2 to capillary blood

Answer 32

PO2 = 160

Enters trachea and PO2 drops to 150

Reaches alveolar air PO2=100 and PCO2= 40

Mixed venous blood comes in with a PO2=40 and PCO2=46

O2 moves in CO2 moves out and as the blood passes alveolar air and changes blood to PO2=100 and PCO2=40

Question 33

What does it mean when systemic arterial blood equals the alveolar air?

Answer 33

Blood is fully oxygenated