3.2 Gas Exchange Flashcards
Has exchange occurs in the…
Alveoli
Alveoli are a good exchange surface because they have these features:
A large surface area
A thin permeable surface
A large diffusion gradient
The pulmonary artery brings deoxygenated blood from the heart to the lungs, it branches…
Inside the lungs into a network of capillaries that surround each alveolus.
The capillaries from the pulmonary artery eventually…
Join up to form branches of the pulmonary vein, which takes oxygenated blood back to the heart from the lungs
The inner surface of the alveoli is always…
Moist, the cells produce a fluid which stops them from drying out.
The fluid inside the alveoli contain a…
Surfactant
A surfactant is like a …
Detergent - and reduces the surface tension and stops the alveoli from sticking together when breathing
The wall of the alveolus is made up of a layer of very thin, flattened cells called an…
Epithelium (this is the gas exchange surface)
The capillary also has a thin wall made of…
Thin, flat cells
The capillary brings deoxygenated blood to the alveolus all the time, oxygen dissolves in the layer of Liquid inside of the alveolus
The oxygen then diffuses through the alveolus wall and the capillary wall into the blood
The capillaries surrounding the alveoli are…
Narrow - same diameter as a RBC, the RBC’s are slowed down as they flow through them, allowing more time for diffusion
A large surface area because:
There are millions of tiny alveoli in each lung
Each alveolus is folded; even greater surface area in the space available
A thin permeable surface because:
The epithelium of the alveolus is made of very thin, flattened cells
The wall of the capillary is also made of very thin, flat cells
The capillary walls are in close contact with the alveolus walls
A large diffusion gradient because:
Ventilation brings air high in oxygen and low in carbon dioxide into the alveoli and takes away air high in carbon dioxide and low in oxygen
Capillaries constantly being deoxygenated blood to the alveoli and remove oxygenated blood
