Lecture 1

Question 1

Do the respiratory gases move due to pressure differences?

Answer 1

Yes

Question 2

Which one (between inspiration and expiration) is an active process and why? (Clue: diaphragm muscles)

Answer 2

Inspiration. Because during inspiration diaphragm muscles contract.

Question 3

What happens to the volume, pressure and the air when the ribs relax(during expiration).

Answer 3

Volume decreases, pressure increases and the air rushes out of the lungs.

Question 4

Is it true that lungs are not made of muscles?

Answer 4

Yes

Question 5

Describe the relationship between volume and pressure.

Answer 5

When volume increases pressure decreases and vice versa.

Question 6

Do Diaphragm muscles relax during expiration

Answer 6

Yes true

Question 7

Which one , between concentration(or percentage) and partial pressure, of Oxygen changes with altitude.

Answer 7

Partial pressure. Percentage or concentration remains the same.

Question 8

Does the partial pressure of Oxygen increase or decrease with an increase in altitude(as we go higher)

Answer 8

The partial pressure of Oxygen decreases with increasing altitude.

Question 9

Between PaO2 and CaO2, which one is the total amount of oxygen

Answer 9

CaO2

Question 10

Oxyhaemoglobin is 97% of oxygen bound to haemoglobin and 3% oxygen is dissolved in plasma, which one contributes to PaO2 and which one contributes to percent saturation.

Answer 10

The 3% dissolved in plasma contributes to PaO2 and the oxyhaemoglobin contributes to percent saturation.
CaO2= (bound to haemoglobin) + (dissolved in plasma)

Question 11

Where does loading of haemoglobin and unloading occur respectively and at a low or high oxygen partial pressure and also determined the percent saturation.

Answer 11

Loading occurs at the lungs and unloading occurs at peripheral tissues. Loading occurs at high partial pressure and unloading at lower partial pressure . Partial pressure and percent saturation are directly proportional.

Question 12

Does haemoglobin unloading decrease or increase Percent Saturation

Answer 12

Haemoglobin unloading decreases percent saturation because then the amount of oxygen bound to haemoglobin decreases as the oxygen is moved from haemoglobin to peripheral tissue.

Question 13

Does the partial pressure of Oxygen determine the percent saturation

Answer 13

Yes and not the other way around.

Question 14

What is the main stimulus that triggers an increased respiratory rate and which receptors detect it.

Answer 14

A decrease in PaO2 (less than 60mmHg) and is detected by peripheral chemoreceptors.

Question 15

Which other two stimuli can trigger an increase in respiratory rate when detected by central chemoreceptors.

Answer 15

An increase in H+ ions (a decrease in pH) and and increase in PaCO2

Question 16

What is (a-v) difference

Answer 16

Atery-venous difference at the tissue level

Question 17

What is the A-a gradient

Answer 17

The difference between Alveolar(lungs) and artery at the lungs level.

Question 18

If the CaO2 is 200ml O2/L and CvO2 is 150ml O2/L what is the a-v difference

Answer 18

a-v difference is 50ml O2/L. That is the amount of oxygen extracted by the tissues.

Question 19

Is it true that low PO2 causes vasoconstriction in both the se ystemic and pulmonary capillaries

Answer 19

Vasodilation in the systemic capillaries to increase oxygen flow to the organs that need it. There will be pulmonary vasoconstriction to divert blood to better ventilated alveoli. So that’s false

Question 20

Is asthma characterised by a struggle to exhale

Answer 20

Yes. It’s an obstructive condition whereby one struggles to exhale.

Question 21

Contrary to an obstructive condition, what is a restrictive condition.

Answer 21

A condition whereby you struggle to inhale or get air into the lungs.

Question 22

FEV1= volume of air forcibly expired in 1 second and FVC=  volume of air forcibly expired after  maximal inspiration.
FEV1/FVC = % of FVC that can be expired in 1 second.  Do you think it's true that  FEV1/FVC > 70% + a decreased  FVC shows obstructive or restrictive disorder?

Answer 22

It shows a restrictive disorder because it shows a high FEV1 (increased expiration) and a low FVC (decreased inspiration).

Question 23

Minute ventilation(VE) =Respiratory Rate× Tidal Volume 
Alveolar Ventilation (VA) = RR × (TV- dead space

Answer 23

Yesss

Question 24

Define diffusion defect?

Answer 24

It is the deficiency of oxygen struggling to diffuse from the lungs into the artery.

Question 25

Oedema and thickened alveolar wall can cause diffusion defect. Is it true that PAO2-PaO2 > 10mmHg indicates diffusion defect?

Answer 25

Yes it is -True

Question 26

Is CO2 far more soluble than O2

Answer 26

True

Question 27

Does diffusion defect result in reduced both PaO2 and PaCO2?

Answer 27

False.

PaO2 decreases but PaCO2 remains normal (REM the definition of diffusion defect)

Question 28

Does diffusion defect affect CO2 from being expired.

Answer 28

No it only affects the diffusion of Oxygen from the lungs into the artery.