Changes

===Alveoli===

===Alveoli===

Alveoli are minute, polygonal chambers, whose diameter changes with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]], and varies by species. The wall of the alveoli is extremely thin, consisting of 2 irregular layers of epithelial sheets, 'sandwiching' a network of capillaries. Thus the ''Blood-Gas Barrier'' is just a single basal lamina - ideal for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]]. The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.

Alveoli are minute, polygonal chambers, whose diameter changes with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]], and varies by species. The wall of the alveoli is extremely thin, consisting of 2 irregular layers of epithelial sheets, 'sandwiching' a network of capillaries. Thus the ''Blood-Gas Barrier'' at the thinnest portions is a tripartite structure consisting of  the pulmonary capillary endothelium, a common basal lamina and the alveolar epithelium- ideal for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]]. The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.

==Function==

==Function==