Common Lung Pathologies Affecting Diffusion Flashcards
- Name four common respiratory pathologies.
Emphysema, asthma, fibrotic lung disease and pulmonary oedema.
What happens in emphysema and what effect does it have on pulmonary pressure?
Destruction of the alveoli results in a decrease in the surface area and so the partial pressure fro oxygen decreases and is low.
What happens in fibrotic lung disease?
There is a thickened alveolar membrane due to the build up of fibrous tissue under the connective tissue and elastic tissue of the lungs and it also ends up forming in between the type I alveolar cells and the type II alveolar cells and this slows gas exchange. There is also a loss in compliance which may decrease alveolar ventilation. The partial pressure for oxygen then falls and there is a lower partial pressure gradient and so less oxygen goes into the blood.
What happens in pulmonary oedema?
Fluid from the interstitial fluid increase the diffusion distance, this doesn’t really affect the partial pressure of carbon dioxide because it is highly soluble in water, but oxygen isn’t soluble and so it is difficult for the oxygen to travel the long distance.
Do emphysema and fibrotic lung disease also affect carbon dioxide?
Yes
What happens in asthma and what does it cause?
There is an inappropriate constriction of the smooth muscle in the bronchioles and so the resistance in the airways is increased and so that decrease airway ventilation. This lead to a low partial pressure in the lungs and so therefore only a small partial pressure of oxygen will be present in the circulation.
Does emphysema affect diffusion or ventilation?
Does emphysema affect expiration or inspiration?
It affects diffusion more but it still partially affects ventilation and the problem is in expiration rather than inspiration. There is also an increase in compliance.
does asthma affect ventilation of diffusion?
It affects the ventilation and not diffusion
What does pulmonary oedema affect?
It affects diffusion rate and not ventilation
Does fibrotic lung disease affect ventilation?
It affects ventilation mostly during inspiration.
What is the main cause of emphysema?
Smoking
How does smoking cause emphysema?
There are constituents within the cigarettes than stimulate an enzyme called elastase, which breaks down the elastic fibres and so it breaks down the alveolar wall.
What is the surface area of an alveoli in emphysema?
Reduced surface area
