3. Physical Principles of Gas Exchanges; Diffusion of Oxygen and Carbon Dioxide Through Respiratory Membrane

Question 1

Once alveoli are ventilated with fresh air, next step in respiratory process is _____ of ____ from _____ into ______ ______ and diffusion of______ in opposite direction

Answer 1

diffusion
O2
Alvioli 
Pulmanary Blood
CO2

Question 2

 Diffusion = ______motion of molecules

Answer 2

Random

Question 3

Gases involved in respiratory physiology are?
a. Free to move 
b. Bound to each other
c. Responsible for the partial pressures?
d. Dissolved gasses in the the blood 
e A & C
f. ACD
g. bdc

Answer 3

e. free to move and responsible for the partial pressures

Question 4

Is energy need for diffusion to occur? If so how is it provided?

Answer 4

yes; kinetic motion of molecules themselves

Question 5

Complete the following sentence regarding the properties of molecular basis of gas diffusion: ____ movement at ___ velocities until collision; then _____ in other direction until other collision

Answer 5

Linear,
HIGH
bounce away

Question 6

molecules move ____ and _____

Answer 6

fast

randomly

Question 7

Diffusion rate is directly proportional to _______ _____

Answer 7

concentration gradient

Question 8

Pressure of a gas acting on surfaces of airways and alveoli is directly proportional to ________ ____molecules. Is true for? Single gas pressure or multiple?

Answer 8

the concentration of the gas molecules

true for single gasses

Question 9

Pressure caused by each gas alone is called?

Answer 9

called partial pressure (Px)

Question 10

Diffusion rate of each gas is ______ ______ to its partial pressure gradient.

Answer 10

directly proportiona

Question 11

Total gas pressure of a mixture of gases ( Ptot ) equals?

Answer 11

The sum of partial pressures of all gases

Question 12

Ptot = r

Answer 12

PO2 + PN2 + PCO2 + Pother

Question 13

Order the gasses in order of highest partial pressure to lowest. ( In the air)
PN2, PO2 , PCO2, Pother

Answer 13

PN2,
P02
PCO2
Pother

Question 14

True or false. Gas dissolved in water and tissues exerts its own partial pressure on surface of membrane in opposite way as gas does in gas phase

Answer 14

False. Gas dissolved in water and tissues exerts its own partial pressure on surface of membrane in same way as gas does in gas phase

Question 15

Partial pressure of a dissolved gas is determined by what two factors?

Answer 15

it’s concentration & solubility coefficient

Question 16

Henry law states that?

Answer 16

Partial Pressure = Concentration of the dissolved gas/ Solubility Coeff.

Question 17

The Measure of electro-chemical attraction that a dissolved gas has to water molecules is otherwise known as?

Answer 17

Solubility coefficient

Question 18

If a gas is highly soluble, will more or less gas molecules be able to dissolve before the partial pressure of that gas within the solution increases?

Answer 18

MORE

Question 19

True or false, CO2 is 24 times more soluble than O2 in fluid?

Answer 19

True

Question 20

With temperature being constant order these from most soluble to least?
CO2,N2, O2 CO, Helium

Answer 20

CO2
O2
CO
N2

Helium

Question 21

PO2 in gas phase in alveoli (PAO2) <> PO2 dissolved in blood (PaO2)

Answer 21

PA02&raquo_space;PaO2

Question 22

Net diffusion of O2 is from ____ to blood

Answer 22

Alveoli to pulmonary arterial ( Due to partial pressure gradient of O2)

Question 23

PCO2 in gas phase in alveoli (PACO2) &laquo_space;or&raquo_space;PCO2 dissolved blood (PaCO2)

Answer 23

PACO2 &laquo_space;PaCO2

Question 24

Direction of Net diffusion of CO2 ?

Answer 24

From pulmonary arterial blood to alveoli

Question 25

True or false?Water molecules, as other dissolved gas molecules, are continually escaping from water surface into gas phase

Answer 25

True.

Question 26

Partial pressure exerted by Which water molecules is called water vapor pressure (Ph2o)

Answer 26

Water molecules, as other dissolved gas molecules, are continually escaping from water surface into gas phase

Question 27

What is the purpose of water vapor in the air passageways?

Answer 27

Water vapor humidifies inspired air in passageways

Question 28

As Temp increases, kinetic activity of molecules and likelihood that will escape from water surface into gas phase increase or decreases?

Answer 28

Increase. | Thereby increasing their partial pressures/

Question 29

Net rate of diffusion in fluids is affected by pressure difference + several other factors? What are they?

Answer 29

``` Solubility of gas in fluid Cross-sectional area of fluid Distance through which gas must diffuse Molecular weight of gas Temperature of fluid (in body, remains constant ```

Question 30

How do you calculate diffusion rate? ( EQN)

Answer 30

Diffusion rate ~ [(P1-P2 ) * Area * Solubility]/[Distance * sqrt(MW)]

Question 31

Main gases involved in respiration are highly soluble in _____? And Why (3). ( Hint: tissue diffusion)

Answer 31

Lipids. 1. Cell membranes are phospholipid bilayers 2. So diffusion through membrane is not an issue 3. Diffusion of gases through tissues will therefore be almost = to diffusion through water

Question 32

True or false. Composition of alveolar air = atmospheric air

Answer 32

False. | Alveolar air is only partially replaced by atmospheric air with each breath

Question 33

What are the difference between alveolar air and atmospheric air, if any?

Answer 33

Alveolar air is only partially replaced by atmospheric air with each breath ALV air = O2 is constantly being absorbed into pulmonary blood from alveolar air CO2 is constantly diffusing from pulmonary blood to alveoli Dry atmospheric air that enters airways is humidified before reaches alveoli

Question 34

____ Air Almost entirely composed of nitrogen and oxygen

Answer 34

Atmospheric air

Question 35

Atmospheric air has Almost no _______and little ____ vapor

Answer 35

carbon dioxide | water

Question 36

As soon as air enters airways, it is exposed to _______covering surfaces and gets _____?

Answer 36

fluids | humidified

Question 37

When atmospheric air enters the air ways and gets humidified, ________ will dilute other gases (hint humidified)

Answer 37

Water vapor

Question 38

Rate of removal of excess gas from alveoli depends on?

Answer 38

rate of alveolar ventilation (VA)

Question 39

true or false. Quick replacement of alveolar air | is important in preventing sudden changes in gas concentrations in blood? Why is this important?

Answer 39

False. Slow replacement Is important for this because it stabilizes respiratory control mechanisms

Question 40

Average functional residual capacity (FRC) ~ 2300 ml. is all this brought into the alveoli?

Answer 40

No. ~350 ml of new air per normal resting breath is brought into alveoli. Due to slow removal rate --> important for preventing sudden changes in alveolar blood gas composition

Question 41

The CO2 concentration (CACO2) and PCO2 in alveoli (PACO2) depend on?

Answer 41

1. Excretion rate of CO2 from pulmonary arterial blood into alveoli 2. The rate of alveolar ventilation to expire CO2

Question 42

Increase of CO2 excretion rate ______ C(A)CO2 and alveolar P(A)CO2

Answer 42

increases

Question 43

Increase of ventilation rate _______the alveolar PACO2 and CO2 concentration (CACO2)

Answer 43

decreases

Question 44

A normal expired air is a mixture of_____ and _____air

Answer 44

alveolar air and dead space air

Question 45

True or false alveolar air is the last 1/3 of volume of expired air

Answer 45

True