Physiology Khogali session 1 Flashcards
what is functional residual capacity
the volume remaining in the lungs after a normal, passive exhalation
what is vital capacity
the maximum volume of air that can be exhaled after a maximum inspiration
functional vital capacity is normally about __% of total lung capacity
40
what is total lung capacity
the maximum volume of air that the lungs can hold at the end of maximum inspiration
what is FEV1/FVC% in a patient with pulmonary fibrosis likely to be
85% - because restrictive pattern, both FEV1 and FVC are reduced so ratio doesn’t drop
normal FEV1/FVC ratio
> 75%
FEV1/FVC ratio in asthma
<75%
FEV1/FVC ratio in COPD even after bronchodilator
<70%
COPD spirometry confirmed diagnosis
FEV1/FVC ratio <70% even after bronchodilator
a low PO2 causes pulmonary vaso__________
vasoconstriction
why does heart failure affect pulmonary compliance
Heart failure occurs when the heart muscle doesn’t pump blood as well as it should. Blood often backs up and causes fluid to build up in the lungs and in the legs.
In pulmonary edema, liquid-filled alveoli induce mechanical stress on air-filled alveoli, reducing the compliance of air-filled alveoli, and hence overall lung compliance.
factors that decrease pulmonary compliance
pulmonary fibrosis
pulmonary oedema
lung collapse
pneumonia
absence of surfactant
dynamic airway compression
when we breathe in intrapleural pressure falls, when we breathe out intrapleural pressure rises
this pressure can compress the alveoli
intraairway pressure oppose intrapleural
which pressure opposes intrapleural pressure
intraairway
dynamic airway compression is likely to occur during active _______
expiration
why is it important to not give too much oxygen to COPD patients
excessive oxygen can lead to hypercapnaeic resp failure in COPD patients with chronic CO2 retention
excessive oxygen given to patients with COPD may
- increase V/Q mismatch by diverting blood flow to poorly ventilated alveoli
- increase the release of CO2 from oxygenated Hb. But COPD patients are unable to increase their ventilation to match the increase in CO2 retention
what is emphysema
involves the gradual damage of lung tissue, specifically the destruction of the alveoli. destruction of the elastic component. problem with recoil (expiration)
compliance vs recoil
compliance - how easy it is to stretch the lungs
recoil - the lung’s intrinsic tendency to deflate following inflation
compliance may become abnormally increased if the elastic recoil of the lungs is lost
does emphysema cause increased or decreased compliance
increased
what is the O2 content of arterial blood determined by?
the Hb concentration and the saturation of Hb with oxygen
