Normal lung function Flashcards
During which phase of respiration do we have negative pleural pressure, negative flow, negative alveolar pressure but growing air air volume in the lung?
Inspiration
What does FRC mean?
Functional residual capacity: the volume of air present in the lung after a passive expiration
What is IRV?
Inspiratory reserve volume: the volume of air that can be forcibly inspired after the tidal volume is expired
What is ERV?
Expiratory reserve volume: the volume of air that can be forcibly expelled after the tidal volume is inspired
What is the instrument that measures change in volume in an organ (or the whole body)
Plethysmograph
Variation of volume on variation of pressure indicates what?
Compliance level
You can measure pleural pressure with what instrument?
Cathameter
What are the two determinants of compliance?
Tissue forces
Surface tension
What increases lung tissue force?
When lung scarring occurs (fibrosis)
Does emphysema increases lung tissue force?
No. Emphysema happens when the parenchymal architecture is destroyed
What does pulmonary sufractant do?
Lowers surface tension to ease inflation/deflation of lungs
Promotes alveolar stability
Does pressure increase with tension?
Yes
What are the three determinants of RV (residual lung volume)?
Limit of chest wall
Obstruction while emptying the lungs
Limit of expiratory force
Lung and chest wall recoil inwards. This is a sign of…
Reaching TLC (total lung capacity)
Lung recoils inward and chest all recoils outward. This is a sign of…
Reaching residual lung volume (RV) and the end of functional residual capacity (FRC)
Which is more compliant: the bottom or upper part of the lung?
Bottom
What is the quantity of gas that ends up in anatomical dead space during inspiration?
150ml
Of the minute ventilation, what percentage ends up at the alveoli and what percentage ends up in the dead space?
70% is the alveolar ventilation
30% is the dead space ventilation
In the body, that is water vapour pressure?
47mmHg
What happens during hypoventilation?
Alveolar ventilation is too low:
1- Increase PACO2
2- Increase H+ in blood: respiratory acidosis
What happens during hyperventilation
Alveolar ventilation too high:
1- Decreased PACO2
2- Decrease H+ in blood: respiratory alkalosis
Is the ventilation greatest at the bottom or the top of the lung? Why?
At the bottom: pleural pressure is less negative at the bottom
Increased respiratory workload can be caused by 3 factors. What are they?
Increased resistance
Decreased compliance
Deformed chest wall
Lung fibrosis leads to…
decreased compliance
