Alveolar Gas Exchange

Question 1

perfusion is

Answer 1

blood to lungs

Question 2

ventilation is

Answer 2

gas into lungs

Question 3

air moves from an area of ___ pressure to ___ pressure

Answer 3

high to low pressure

Question 4

pressure differences between two ends of conducting zone occur due to changes in

Answer 4

lung volume

Question 5

airflow can be determined by

Answer 5

ohm’s law

q = P1-P2 / R

Question 6

airway resistance is controlled by

Answer 6

smooth muscle

Question 7

total pressure of a gas mixture is equal to

Answer 7

the sum of pressures of each gas in it

Question 8

the amount of gas that can dissolve in liquid depends on
______ of gas in liquid
_______
______ ______ of gases

Answer 8

solubility of gas in liquid
temperature
partial pressure of the gases - determining factor

Question 9

type 1 pneumocytes

Answer 9

gas exchange - make up most of the membrane

Question 10

type II pneumocytes perform what function

Answer 10

secrete pulmonary surfactant, reabosrb water and sodium

Question 11

ficks law says transfer of gas through a tissue is 
proportional
 to: 
and inversely proportional
 to

Answer 11

proportional to tissue area and difference in gas partial pressure
inversely proportional to tissue thickness

Question 12

alveolar gas exchange depends on two factors:
blood to the lungs or ______ and
gas into the lungs, or ________

Answer 12

perfusion

ventilation

Question 13

perfusion is highest in which part of the lung

Answer 13

perfusion is highest in zone 3 (most inferior part)

Question 14

ventilation is highest in which part of the lung

Answer 14

ventilation is highest in zone 1 (most superior part)

Question 15

airflow can be determined using what equation

Answer 15

difference in pressure over resistance
Ohm’s law
P1-P2 / R

Question 16

the easiest way to change resistance in the lungs (and in circulation) is to decrease _______; this is because a change in this factor will result in a 4x increase in resistance

Answer 16

radius

decreasing the radius of a vessel by a factor of one will result in a fourfold increase in resistance

Question 17

increasing resistance through the bronchioles is performed most easily by decreasing radius
this is controlled by _____ ______

Answer 17

smooth muscle

Question 18

partial pressure of a gas can be determined by multiplying the ______ of that gas in mixture by total pressure

Answer 18

the % of that gas in mixture by total pressure

Question 19

what effect does the addition of water vapor have on the partial pressures of each gas

Answer 19

addition of water vapor takes away from total

Question 20

PO2 in dry air

Answer 20

159

Question 21

PCO2 in dry air

Answer 21

0.2

Question 22

PO2 in alveolar gas

Answer 22

100

Question 23

PCO2 in alveolar gas

Answer 23

40

Question 24

PH2O in dry air

Answer 24

0.0

Question 25

PH2O in alveolar gas

Answer 25

47

Question 26

the three factors affecting the amount of gas that can dissolve in liquid 1. ______ of gas in liquid 2. _________ 3. ________ _____ of gases *** (determining factor)

Answer 26

solubility . of gas in liquid temperature partial pressure of the gases is the determining factor

Question 27

PO2 of arterial blood

Answer 27

95

Question 28

PO2 of venous blood

Answer 28

40

Question 29

PCO2 of arterial blood

Answer 29

40

Question 30

PCO2 of venous blood

Answer 30

46

Question 31

PH2O of alveolar gas, arterial blood and venous blood

Answer 31

47

Question 32

the PO2 concentration of alveoli (100) is controlled by 1. the rate of new air into lungs 2. rate of absorption into blood : ________

Answer 32

250 ml/ O2/min

Question 33

the PCO2 concentration in alveoli (40) is controlled by 1. rate of excretion: ________ 2. rate of new air into lungs

Answer 33

200 ml CO2/min | rate of new air into the lungs decreases proportional to alveolar ventilation

Question 34

components of an alveolar unit (7)

Answer 34

``` surfactant alveolar epithelial cells alveolar epithelial basement membrane interstitial space capillary basement membrane capillary endothelial cells capillary lumen ```

Question 35

type II pneumocytes are responsible for

Answer 35

producing pulmonary surfactant and reabsorbing water and sodium

Question 36

type I pneumocytes make up ___ % of the SA in an alveoli | what function do they perform

Answer 36

95% | gas exchange

Question 37

gas transfer is proportional to _____ and _____ in gas partial pressure gas transfer is inversely proportional to _____ ______

Answer 37

proportional to tissue area and difference in gas partial pressure inversely proportional to tissue thickness

Question 38

CO2 diffuses ____ x more rapidly than O2

Answer 38

20x

Question 39

T/F: the diffusion of each gas is dependent on one another

Answer 39

false | diffusion rates are independent

Question 40

although an RBC will take approximately .75 seconds to span an alveoli, gas exchange occurs in only ____ seconds

Answer 40

.25 seconds | even during exercise, blood isnt moving too quickly for gas exchange to occur

Question 41

limitations of diffusion (4)

Answer 41

1. SA available for diffusion (A) 2. Thickness (T) - aka distance between RBC and alveolus 3. Solubility of gas (D) 4. Pressure gradient (P1-P2) J = A/T * D * (P1-P2)

Question 42

if alveoli are damaged, it decreases the total _____ _____ available for diffusion, affecting total gas exchange

Answer 42

surface area | can occur in disease like emphysema where patients have damaged, ruptured alveoli

Question 43

``` as distance increases, ______ decreases factors that can increase distance include fluid layer alveolar epithelium interstitial space blood vessel wall ```

Answer 43

``` distance increases, diffusion decreases collagen deposition (like with fibrosis) within the interstitial space increases diffusion distance, therefore decreasing diffusion of gases ```

Question 44

diffusion coefficient is dependent on

Answer 44

solubility (O2 is less soluble than CO2) molecular weight (O2 weighs less than CO2) the DCO2 is 20x larger than DO2

Question 45

the PVO2 is equal to ____ mmHg, while the PalvO2 is equal to ___ mmHg, this pressure difference is a large factor in driving oxygen from the alveolus to the capillaries

Answer 45

``` PvO2 = 40 mmHg PalvO2 = 100mmHg (P1-P2 = 60 mmHg) ```

Question 46

the PvCO2 is equal to ___ mmHg, while the PalvCO2 is equal to ___ mmHg, this pressure difference is a factor in driving CO2 out of the veins into the alveoli

Answer 46

``` PvCO2 = 45 mmHg PalvCO2 = 40 mmHg ```

Question 47

N2O can be used to determine if _____ is limited in a patient

Answer 47

perfusion | N2O rapidly increases for Pc =Pa

Question 48

CO can be used to determine if ____ is limited in a patient

Answer 48

diffusion Pc =/= Pa CO doesnt diffuse well but what does binds more tightly to Hb than O2

Question 49

in a large alveolus, _____ will be relatively low

Answer 49

pressure low in large alveolus

Question 50

in small alveolus, _____ is relatively high

Answer 50

pressure high in small alveolus

Question 51

collateral airflow can occur without _____ from small alveolus to large alveolus (pressure moves from high to low)

Answer 51

collateral airflow occurs without surfactant molecules of water in tissue have strong intermolecular interactions that pull them closer surfactant breaks up these interactions

Question 52

_______ reduces surface tension in smallest alveoli more so than larger alveoli; promotes lung expansion during inspiration

Answer 52

surfactant

Question 53

components of surfactant include two phospholipids: | and neutral lipids such as:

Answer 53

DPCC Phosphatidylglycerol/ethanolamin/inotisol neutral lipids? cholesterol

Question 54

surfactant is stored within

Answer 54

immature lamellar bodies

Question 55

surfactant is secreted with

Answer 55

mature lamellar bodies

Question 56

surfactant is recycled by using

Answer 56

multivesicular bodies