Gas Exchange

Question 1

What is alveolar ventilation

Answer 1

Volume of air exchanged between the atmosphere and alveoli per minute

Question 2

What is anatomical dead space

Answer 2

Air which remains in airways which is not available for gas exchange

Question 3

What is the equation for pulmonary ventilation

Answer 3

Pulmonary ventilation (L) = tidal volume (l/breath) x respiratory rate (breath/min) = 6L under resting conditions

Question 4

Why is alveolar ventilation less than pulmonary vent

Answer 4

Coz presence of anatomical dead space

Question 5

How do u work out the alveolar ventilation

Answer 5

AV = (tidal volume - anatomical dead space) x RESP rate = 4.2 l/min under resting conditions

Question 6

How do u increase pulmonary ventilation

Answer 6

During exercise
Both depth - tidal volume and rate of breathing - RESP rate must increase
But due to dead space it is better to increase depth of breathing

Question 7

What is ventilation perfusion

Answer 7

Transfer of gases between body and atmos deals on
Vent - rate which gas passing though lungs
Perfusion - rate at which blood is passing through lungs

Question 8

What is alveolar dead space

Answer 8

Ventilated alveoli which are not adequately perf used with blood as dead space

I’m healthy ppl dead space v small a nd not imp
Increases with disease

Question 9

What does accumulatin of carbon dioxide do to alveolar dead space

Answer 9

Increases perfusion decreases airway resist lading to increase airflow

Increased vent
Put vasodilator
Increases blood flow

Question 10

What are the four factors influence the rate of gas exchange across alveolar mem

Answer 10

Partial pressure of oxygen and carbon dioxide
Diffusion coeff for oxy and co2
SA of alv mem
Thickness of alv mem

Question 11

What is Dalton’s law of partial pressure

Answer 11

Total pressure exerted by gaseous mix = sum of partial pressures of each individual component in the gas mix

Question 12

What does the partial pressure of a gas determine

Answer 12

The pressure gradient for that gas

Question 13

The partial pressure of a gas is

Answer 13

Pressure that one gas in a mix of gases would exert if it were only gas present in the whole volume occupied by the mix at a given temp

Question 14

What si the alveolar gas eqn

Answer 14

PAO2 = PiO2 - [PaCO2/0.8]

Question 15

The air in the RESP tract is

Answer 15

Saturated with water (water vapour)

Question 16

What does the water vapour contribute to the pressure

Answer 16

47mmHg to total pressure in lungs

Question 17

How do we convert to PKa

Answer 17

Convert divide mmHg by 7.5

Question 18

Across pulmonary caps what Is the pp oxy and co2

Answer 18

Oxy - 60mmHg

Co2 - 6 mmHg

Question 19

What is the pp oxy and co2 in the systemic caps

Answer 19

Oxy - >60 mmHg

Co2 - > 6 mmHg

Question 20

Is co2 or O2 more sol in mems

Answer 20

Co2

Question 21

What is the solubility of gas in membranes known as

Answer 21

Diffusion coefficient

Diff coeff of co2 20X > than that of O2

Question 22

What does a big gradient between PAO2 and PaO2 mean

Answer 22

Indicate problems with gas exchange in the lungs or a right to left shunt in the heart

Question 23

What is Ficks law of diffusion

Answer 23

Amount of gas that moves across sheet of tissue in unit time is proportional to the area of the sheet but inversely proportional to its thickness

Question 24

What increases the SA of the lungs

Answer 24

Alveoli

Question 25

What are alveoli

Answer 25

Thin walled inflatable sacs
Function in gas exchange 
Walls consist of type 1 alveolar cells 
Pulmonary caps encircle each alveolus 
Narrow interstitial space

Question 26

What are some nonresp functions of the RESP syst

Answer 26

Route for water loss
Heat elim 
Helps maintain normal acid-base balance 
Enable speech 
Defend ag inhaled forgein matter 
Removes various materials 
Nose serves as organ of smell

Question 27

What is pulmonary respiration

Answer 27

Volume of air breathed in and out per min