Changes

**Right Lung = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|200px|'''Schematic Diagram showing the route air takes through the respiratory system''']]

**Right Lung = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|200px|'''Schematic Diagram showing the route air takes through the respiratory system''']]

*The bulk of the lung consists of bronchi, blood vessels and connective tissue. The terminal bronchioles have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.

*The bulk of the lung consists of bronchi, blood vessels and connective tissue. The terminal bronchioles have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.

**Alveolar Ducts: These have alveoli which open on all of it's sides, they have no 'walls' as such. Openings to individual alveoli are guarded by smooth muscle.

**'''Alveolar Ducts''': These have alveoli which open on all of it's sides, they have no 'walls' as such. Openings to individual alveoli are guarded by smooth muscle.

**Alveolar Sacs: These are rotunda-like areas on the end of the alveolar ducts, usually there are clusters of these at the end of each duct.

**'''Alveolar Sacs''': These are rotunda-like areas on the end of the alveolar ducts, usually there are clusters of these at the end of each duct.

**Alveoli: These are minute, polygonal chambers, whose diameter changes with the processes of inspiration and 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 gaseous exchange.

**'''Alveoli''': These are minute, polygonal chambers, whose diameter changes with the processes of inspiration and 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 gaseous exchange.

The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.

The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.