Quiz 4 Physical Principles of Gas Exchange

Question 1

What is the mechanism and rate of molecule transfer dependent on ?

Answer 1

• Physics of gas diffusion

- Partial pressures of gases involved

Question 2

What is the energy source for gas diffusion?

Answer 2

Kinetic motion

Question 3

Molecular movement is ______ and ______

Answer 3

Continual and random

Question 4

Movement of a gas in one direction is the effect of what?

Answer 4

Concentration gradient

Question 5

Direction of diffusion occurs for areas of ______ to _______ concentration.

Answer 5

High to low

Simple diffusion

Question 6

Rate of diffusion is dependent on what?

Answer 6

Pressure

Question 7

What is partial pressure?

Answer 7

The pressure a gas would exert by it’s self.

Question 8

What is the total pressure of a mixture?

Answer 8

The summation of all the partial pressures in a gas

Question 9

True or False: Each gas exerts its own individual pressure on the respiratory wall surface?

Answer 9

True

Question 10

What is the mixture of air?

Answer 10

Nitrogen 79%

Oxygen 21%**

Question 11

What is the total pressure of the air mixture?

Answer 11

760 mm Hg*

Question 12

What does 1 atmosphere equal?

Answer 12

760 mm Hg*

Question 13

What is the partial pressure of nitrogen in one atmosphere?

Answer 13

600 mm Hg

Question 14

What is the partial pressure of oxygen in one atmosphere?

Answer 14

160 mm Hg

Question 15

What does Henry’s Law say about the solubility of a gas in a liquid (what is it dependent on)?

Answer 15

Depends on the

• temperature
• partial pressure of the gas over the liquid
• nature of the solvent
• nature of the gas

For a gas, low temp and high pressure increases solubility

Question 16

What does highly soluble mean?

Answer 16

When dissolved molecules are attracted by water, more can be accumulated without building up excess pressure in a solution.

Question 17

What does poorly soluble mean?

Answer 17

Molecules which are repelled by water will dissolve less and have lower concentration

Question 18

What is the rate of net diffusion determined by?

Answer 18

Difference of partial pressures (pp)*

Question 19

If the pp of gas in the alveoli greater than blood which way will the gas move?

Answer 19

The gas will move into the blood (oxygen)

Question 20

What is the vapor pressure when a gas mixture is fully humidified at 37 C?

Answer 20

47 mmHg*

Question 21

What is vapor pressure of water?

Answer 21

Partial pressure of water escaping surface into gas phase

Question 22

What factors affect gas diffusion rates in fluid?

Answer 22

• Pressure differences
• Gas solubility in fluid
• Area of fluid
• Distance which gas must diffuse
• Molecular weight of gas
• Temperature of fluid

Question 23

What is diffusion coefficient of the gas?

Answer 23

Characteristics of the gas which affect the ability and rate of net diffusion.
(Solubility/ square root Molecular weight)

Question 24

What is the limiting factor for gas movement into tissues?

Answer 24

Diffusion rate of gas through tissue water

Respiratory gasses are highly soluble in lipids (cell membranes)

Question 25

True or False: Alveolar air has the same gas concentration as atmospheric air?

Answer 25

False Different because alveolar air is partially replaced by atmospheric air during each breath

Question 26

Normal alveolar ventilation removes half of the gas in ____ seconds? What about hyper/hypoventilating?

Answer 26

17 seconds Hyperventilating removes gas faster Hypoventilating removes gas slower

Question 27

What is the normal alveolar PO2?

Answer 27

100 mm Hg

Question 28

What is the normal alveolar PCO2?

Answer 28

40 mm Hg

Question 29

Alveolar air is expired at ____________

Answer 29

end of exhalation

Question 30

How thick is the alveolar membrane?

Answer 30

0.6 micrometers

Question 31

What is the total surface area of the alveoli?

Answer 31

70 square meters

Question 32

How wide are the alveolar capillaries?

Answer 32

5 micrometers

Question 33

What are the factors that affect rate of gas diffusion through the respiratory membrane? What Law?

Answer 33

Frick's Law 1. Thickness of the membrane 2. Surface area of the membrane 3. Diffusion coefficient 4. Pressure difference across the membrane

Question 34

CO2 diffuses ___ times faster than Oxygen.

Answer 34

20

Question 35

Oxygen diffuses _______ times faster than Nitrogen.

Answer 35

2

Question 36

Can the factors which affect diffusion through the respiratory membrane affect the diffusion capacity?

Answer 36

Yes

Question 37

What is the diffusing capacity?

Answer 37

Volume of a gas that will diffuse through the respiratory membrane each minute for a pressure difference of 1 mm Hg.

Question 38

What is the diffusing capacity for O2?

Answer 38

21 mL/min/mmHg

Question 39

How do you get the total quanitity of O2 diffusing across the membrane per minute?

Answer 39

Pressure difference multiplied by the diffusing capacity.

Question 40

How much does exercising increases the diffusing capacity to?

Answer 40

65 mL/min/mmHg

Question 41

What increases the diffusion capacity during exercising?

Answer 41

- Recruitment of capillary fields (surface area) | - Better ventilation/perfusion match with blood (All ZONE 3)

Question 42

CO2 diffusing capacity estimate is based on the ______ _______.

Answer 42

diffusion coefficient | unable to calculate, so based off of this

Question 43

Diffusing capacity of CO2 at resting is ________ and during exercise is ______?

Answer 43

400 mL/min/mmHg, 1200 mL/min/mmHg

Question 44

If the V/Q ratio is either zero or infinity there is ______ exchange of gases.

Answer 44

NO

Question 45

When V/Q = Zero this means what?

Answer 45

There is no ventilation= airway obstruction | Shunt

Question 46

When V/Q = infinity this means what?

Answer 46

There is no perfusion= PE | Dead Space

Question 47

Normal deoxygenated blood PO2 is _____..

Answer 47

40 mmHg

Question 48

Normal deoxygenated blood PCO2 is _____.

Answer 48

45 mmHg

Question 49

Inspired air PO2 is ______ mmHg

Answer 49

150 mmHg 713mmHg (ppAir)*0.21= 150mmHg

Question 50

Inspired air PCO2 is ______mmHg.

Answer 50

0 mmHg

Question 51

What happens in emphysema?

Answer 51

Dissolution of many alveolar walls to coalesce alveoli into larger chambers (surface area decreases up to 5-fold) Can effect gas diffusion rate through respiratory membrane d/t decreasing surface area

Question 52

Normal alveolar partial pressures: Alveolar PO2:____mmHg Alveolar PCO2: ___mmHg

Answer 52

100 mmHg | 40 mmHg

Question 53

Perfusion, but no ventilation? | V/Q is ____ normal?

Answer 53

Physiologic Shunt- total amt blood shunted/min Below/ 0

Question 54

Ventilation, but no perfusion? | V/Q is ____ normal?

Answer 54

Dead space Above/ Infinity