Respiratory [Perfusion & Flow] Flashcards
The pul vein is contaminated by blood from the ___ that by-passes the lungs, called an ____.
The pul vein is contaminated by blood from the tracheobronchial circulation that by-passes the lungs, called an anatomical shunt.
Typical pul pressure =
Typical mean pul pressure =
Typical mean systemic pressure =
28/10mmhg
14
93
Blood can only be pumped to a heart of __ at systole and ___ during diastole.
35cm
13cm
Mean P eqn =
Diastole + 1/3PP
3 features of oedema
Left heart failure
Systemic hypoxia
Breathless ‘dyspnoea’
A decrease in resistance of the pulmonary circuit means there is a increase/decrease in ____ causing ___ and ____ of blood vessels that were previously closed.
Decrease
Pulmonary arterial pressure
Distension and recruitment
Hypoxia is due to a decrease in ___ levels, causing ___ of alveoli and limits ____ to alveoli with low ____. Hypoxia causes ____ and is due to ___ failure. ____ has the same effect.
Oxygen Vasoconstriction Blood flow Pul hypertension Right heart failure Hypercapnia
Hypoxia is due to an ___ response where ____ build up and increase ___ and ____.
Inflammatory
Mucus and fluid
Increase resistance
Increase dead space
Blood flowing through poorly ventilated alveoli as found at the top of the lung forms a _____ reducing ___ levels in the ____.
Physiological shunt
PaO2
Pulmonary vein
Pressure ratio at top of lungs
Consider PA, Pa, Pv
PA>Pa>Pv
Pressure ratio in middle of lung
Consider PA, Pa, Pv
Pa>PA>Pv
Pressure at bottom of lung (zone 3)
Consider PA, Pa, Pv
Pa>Pv>PA
Ideal ventilation-perfusion ratio =
Alveolar ventilation (f x Vt) / CO
Ideal VA/Q is ____ but actual is ___
1
0.8
Values
Q =
Va=
Q = 4.9 L/min Va= 4.24 L/min
Factors controlling diffusion across alveolar membrane
Area Thickness of tissue Partial p diff across tissue Solubility of gas M gas
Partial pressure difference:
Alveoli —> blood
Blood —> alveoli
60
6
CO2 is ___ more solvable than O2 and diffuses ___ faster. However the lung equilibrium for exchange is similar because _____ and ____.
25x
0.86x
Reaction to release CO2 is slow
Driving F CO2 from blood to alveoli is 10x less than alveolus to blood
Diffusion limited
Includes reaction time for bonding with haemoglobin Eg.CO
Perfusion limited
Eg. NO or O2. Limit to transport these gases is blood flow
Sheet flow describe
Pulmonary capillaries are densely packed around the alveoli such that individual capillary walls blend together leading to a sheet like micro-vascular structure with interstitial pillars
Due to gravity, both ventilation and perfusion are lowest/highest in the ___ of the lung. However, as ____ has more mass than ____, the increase in ___ from the apex to the base is greater than the increase in _____. This means the V/Q ratio increases/decreases from the apex to the base.
Apex Blood Air Perfusion Ventilation Decreases
