Respiratory Physiology III: Pulmonary Gas Exchange (Exam IV)

Question 1

Blood coming into the capillaries (before diffusion through the pulmonary artery):

PO2:
PCO2:

Answer 1

PO2: 40 mmHg
PCO2: 45 mmHg

Question 2

In the alveoli:

PAO2:
PACO2:

Answer 2

PAO2: 100 mmHg
PACO2: 40 mmHg

Question 3

Blood exiting the capillaries (after diffusion through the pulmonary vein):

PO2:
PCO2:

Answer 3

PO2: 100 mmHg
PCO2: 40 mmHg

Question 4

When blood reaches the pulmonary veins, PO2 & PCO2 have reached:

Answer 4

Equilibrium

Question 5

When blood enters the left heart the PO2 is actually at _____ & this is due to ____

Answer 5

PO2= 95 mmHg
Bronchial circulation

Question 6

To calculate a partial pressure, you must determine the _____ of the gas to other molecules

Answer 6

Relative concentration

Question 7

Refers to the pressure of one gas in a mixture of gases:

Answer 7

Partial pressure (Pgas)

Question 8

Equation for partial pressure of a gas:

Answer 8

Pgas = PATM x Fractional concentration of gas

Question 9

The atmospheric pressure (PATM) at sea level is ____ and air is composed of:

Answer 9

760 mmHg; 79% nitrogen & 21% oxygen

Question 10

The fraction of inspired oxygen:

Answer 10

FiO2

Question 11

Calculate the partial pressure of oxygen in our atmosphere:

Answer 11

PO2= 760 mmHg x 0.21
=160 mmHg

Question 12

As air passes through the conducting zone of the lung, it is humidified creating:

Answer 12

Creating a partial (vapor) pressure for water

Question 13

As air passes through the conducting zone of the lung, it is humidified creating a partial vapor pressure for water (PH20) which =47 mmHg. This addition of water does what to the partial pressure of oxygen:

Answer 13

Decreases it

Question 14

Calculate the partial pressure of oxygen with the addition of the partial vapor pressure of water at 47 mmHg:

Answer 14

PO2= (760mmHg - 47mmHg) x 0.21
=149 mmHg

Question 15

At normal alveolar ventilation & O2 absorption rates (250 mL/min), PAO2 is:

Answer 15

100 mmHg

Question 16

Increasing alveolar ventilation will _____ PAO2

Answer 16

Increase

Question 17

Equation for alveolar ventilation:

Answer 17

Alveolar ventilation = (TV-DS) x RR

Question 18

According to the equation:
Alveolar ventilation = (TV-DS) xRR

You can increase alveolar ventilation by:

Answer 18

Increasing TV and/or increasing RR

Question 19

A gas within a liquid also exerts a _____

Answer 19

Partial pressure

Question 20

To calculate the partial pressure in a liquid solution, the ____ and the ____ of the gas are required

Answer 20

Relative concentration & solubility coefficient

Question 21

Attractability of molecules to water

Answer 21

Solubility coefficient

Question 22

If the solubility coefficient number is high:

Answer 22

The gas diffuses in the liquid quickly

Question 23

Henry’s Law:

Answer 23

Partial pressure = (Concentration of dissolved gas) / (Solubility coefficient)

Question 24

Concentration of dissolved gas equation:

(rearrangement of Henry’s Law)

Answer 24

Conc. of dissolved gas = solubility coefficient x partial presssure

Question 25

At a constant temp, the amount of gas that dissolves in liquid is _____ to the partial pressure and the solubility

Answer 25

Directly proportional

Question 26

Compare the solubility of CO2 to O2:

Answer 26

CO2 is more soluble than O2

Question 27

Why would a patient who has trouble oxygenating their blood be able to transport and get rid of CO2 more easily?

Answer 27

Because CO2 is more soluble

Question 28

The higher the partial pressure of the gas, the ______ we will be able to dissolve into the liquid

Answer 28

More

Question 29

Gas exchange at the respiratory membrane depends on: (2)

Answer 29

1. Transport rate through the respiratory membrane
2. The rate of alveolar ventilation

Question 30

An increase in alveolar ventilation will ______ PAO2 and gas exchange with an upper limit of ______ (which is _____)

Answer 30

Increase; 149 mmHg; the PAO2 of humidified air

Question 31

The rate of alveolar ventilation has an upper limit of 149 mmHg. Describe a scenario where this limit might be surpasses:

Answer 31

Patients that are on oxygen may have a higher FIO2 (fraction of inspired oxygen) than 21% which would increase the partial pressure of oxygen