Lecture 1 Flashcards
Do the respiratory gases move due to pressure differences?
Yes
Which one (between inspiration and expiration) is an active process and why? (Clue: diaphragm muscles)
Inspiration. Because during inspiration diaphragm muscles contract.
What happens to the volume, pressure and the air when the ribs relax(during expiration).
Volume decreases, pressure increases and the air rushes out of the lungs.
Is it true that lungs are not made of muscles?
Yes
Describe the relationship between volume and pressure.
When volume increases pressure decreases and vice versa.
Do Diaphragm muscles relax during expiration
Yes true
Which one , between concentration(or percentage) and partial pressure, of Oxygen changes with altitude.
Partial pressure. Percentage or concentration remains the same.
Does the partial pressure of Oxygen increase or decrease with an increase in altitude(as we go higher)
The partial pressure of Oxygen decreases with increasing altitude.
Between PaO2 and CaO2, which one is the total amount of oxygen
CaO2
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.
The 3% dissolved in plasma contributes to PaO2 and the oxyhaemoglobin contributes to percent saturation.
CaO2= (bound to haemoglobin) + (dissolved in plasma)
Where does loading of haemoglobin and unloading occur respectively and at a low or high oxygen partial pressure and also determined the percent saturation.
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.
Does haemoglobin unloading decrease or increase Percent Saturation
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.
Does the partial pressure of Oxygen determine the percent saturation
Yes and not the other way around.
What is the main stimulus that triggers an increased respiratory rate and which receptors detect it.
A decrease in PaO2 (less than 60mmHg) and is detected by peripheral chemoreceptors.
Which other two stimuli can trigger an increase in respiratory rate when detected by central chemoreceptors.
An increase in H+ ions (a decrease in pH) and and increase in PaCO2
What is (a-v) difference
Atery-venous difference at the tissue level
What is the A-a gradient
The difference between Alveolar(lungs) and artery at the lungs level.
If the CaO2 is 200ml O2/L and CvO2 is 150ml O2/L what is the a-v difference
a-v difference is 50ml O2/L. That is the amount of oxygen extracted by the tissues.
Is it true that low PO2 causes vasoconstriction in both the se ystemic and pulmonary capillaries
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
Is asthma characterised by a struggle to exhale
Yes. It’s an obstructive condition whereby one struggles to exhale.
Contrary to an obstructive condition, what is a restrictive condition.
A condition whereby you struggle to inhale or get air into the lungs.
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?
It shows a restrictive disorder because it shows a high FEV1 (increased expiration) and a low FVC (decreased inspiration).
Minute ventilation(VE) =Respiratory Rate× Tidal Volume Alveolar Ventilation (VA) = RR × (TV- dead space
Yesss
Define diffusion defect?
It is the deficiency of oxygen struggling to diffuse from the lungs into the artery.
Oedema and thickened alveolar wall can cause diffusion defect. Is it true that PAO2-PaO2 > 10mmHg indicates diffusion defect?
Yes it is -True
Is CO2 far more soluble than O2
True
Does diffusion defect result in reduced both PaO2 and PaCO2?
False.
PaO2 decreases but PaCO2 remains normal (REM the definition of diffusion defect)
Does diffusion defect affect CO2 from being expired.
No it only affects the diffusion of Oxygen from the lungs into the artery.
