30 Gas Transport and Ventilation

Question 1

Gas Law–The pressure of a gas =?

Answer 1

the sum of the partial pressure of all its constitutes

Question 2

4 important gases in the body?

Answer 2

N2, O2, CO2, H2O

Question 3

In the air, the atmospheric pressure is approximately equal to the sum of which two pressures?

Answer 3

N2 and O2

Question 4

Atmosphere is approximately % N and % O?

Answer 4

79% N and 21% O

Question 5

Atmospheric pressure at sea level mmHg?

Answer 5

760 mmHg

Question 6

Is the PCO2 greater within the alveoli or in room air?

Answer 6

Much greater in alveoli

Question 7

What is Henry’s Law?

Answer 7

Quantity of dissolved gas= partial pressure x solubility coefficient

Question 8

What are the 3 forms carbon dioxide is transferred in the blood?

Answer 8

dissolved (5%), as bicarbonate (77%), and as carbamino compounds (18%)

Question 9

What drives the diffusion of gases?

Answer 9

a pressure or concentration gradient

Question 10

Does CO2 or O2 have a greater solubility?

Answer 10

CO2

Question 11

Is the CO2 bound to hemoglobin bond strong?

Answer 11

No its weak.

Question 12

What do red blood cells contain that facilitate combination of Co2 and water?

Answer 12

carbonic anhydrase

Question 13

CO2 and water combine to form?

Answer 13

carbonic acid—dissociates to proton and bicarbonate

Question 14

Does the bicarbonate stay in the RBC where it is formed?

Answer 14

no, it diffuses out because of concentration differences

Question 15

What diffuses into RBC in order to maintain electroneutrality when bicarb diffuses out?

Answer 15

chloride—hence the chloride shift

Question 16

What is the volume of gas inspired or expired with each breath?

Answer 16

Tidal Volume

Question 17

What is the minute ventilation?

Answer 17

tidal volume x respiratory rate

Question 18

What is the portion of minute ventilation that does not participate in gas exchange?

Answer 18

dead space ventilation

Question 19

What are the two types of dead space ventilation?

Answer 19

anatomical and physiological

Question 20

What is the portion of minute ventilation that does participate in gas exchange called?

Answer 20

Alveolar ventilation

Question 21

What is alveolar ventilation + dead space ventilation?

Answer 21

minute ventilation

Question 22

What 2 things result in the level of CO2 in the alveolus?

Answer 22

1. How much CO2 is delivered.

2. How much CO2 is eliminated

Question 23

Alveolar PO2 is determined by what 2 factors?

Answer 23

Alveolar ventilation and oxygen consumption

Question 24

What type of motion is it when each molecule moves with random?

Answer 24

Brownian Motion

Question 25

Ficks law of diffusion takes in account which three factors?

Answer 25

1. driving pressure 2. properties of gas 3. properties of the membrane

Question 26

How long is each blood cell in contact with alveolus?

Answer 26

.75 seconds-- only needs .25 seconds to equilibrate

Question 27

Do thick alveolar walls indicate diffusion limitation in the case of hypoxemia?

Answer 27

No- real mechanism is mismatch of ventilation and perfusion

Question 28

O2 content of blood and cardiac output combined is equal to?

Answer 28

O2 delivery

Question 29

What is the shape of the dissociation curve for hemoglobin and oxygen?

Answer 29

sigmoid shaped due to cooperative binding

Question 30

What are the two pools of oxygen being carried in the blood?

Answer 30

Hb bound O2 (98%) + dissolved O2 (2%)

Question 31

Is it more popular to judge blood oxygenation by saturation or PO2?

Answer 31

saturation

Question 32

What occurs if O2 content falls and tissue oxygen delivery cannot be maintained?

Answer 32

Tissue hypoxia

Question 33

What are the 2 most popular reasons O2 content falls?

Answer 33

1. low arterial 02 saturation | 2. low hemoglobin concentration

Question 34

Is the diffusion distance in tissues much greater than in lung?

Answer 34

yes

Question 35

What provides a storage tank for oxygen in the muscle?

Answer 35

myoglobin

Question 36

What increases release of oxygen in the tissues (right shift of curve)?

Answer 36

lowered pH, increased pCO2, increased temp, and increase in 2,3-DPG

Question 37

When does 2,3 DPG get released more?

Answer 37

accumulation of glycolytic intermediates

Question 38

what is true rate limiting step of O2 Transport?

Answer 38

diffusion distance

Question 39

what is the most effective way of increasing oxygen delivery to a given tissue?

Answer 39

recruiting or construction of additional capillaries

Question 40

Gases with a similar solubility in blood and diffusion barrier are said to be what?

Answer 40

perfusion limited

Question 41

Gases with very different solubility in blood and a diffusion barrier are said to be?

Answer 41

diffusion limited

Question 42

True or False: Both oxygen and carbon dioxide are diffusion-limited in tissues

Answer 42

true