Changes

*The left and right lungs lie within their [[Pleural Cavity and Membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity.  

The left and right lungs lie within their [[Pleural Cavity and Membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity. The right lung is always larger than the left, due to the positioning of the [[Heart - Anatomy & Physiology|heart]]. The apex of the lungs is their cranial point.

*The right lung is always larger than the left, due to the positioning of the [[Heart - Anatomy & Physiology|heart]]. The apex of the lungs is their cranial point.

 

*In most species the lungs are divided into lobes by the [[Bronchi and Bronchioles - Anatomy & Physiology|bronchial]] tree:

In most species, the lungs are divided into lobes by the [[Bronchi and Bronchioles - Anatomy & Physiology|bronchial]] tree:

**'''Left Lung''' = Cranial and Caudal lobes.  

 

**'''Right Lung''' = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.

'''Left Lung''' = Cranial and Caudal lobes.  

*The bulk of the lung consists of [[Bronchi and Bronchioles - Anatomy & Physiology|bronchi]], [[Anatomy of Blood Vessels - Anatomy & Physiology|blood vessels]] and connective tissue. The terminal [[Bronchi and Bronchioles - Anatomy & Physiology|bronchioles]] have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.

'''Right Lung''' = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.

**'''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 [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].

 

**'''Alveolar Sacs''': These are rotunda-like areas on the end of each alveolar ducts which are usually present in clusters.

The bulk of the lung consists of [[Bronchi and Bronchioles - Anatomy & Physiology|bronchi]], [[Anatomy of Blood Vessels - Anatomy & Physiology|blood vessels]] and connective tissue. The terminal [[Bronchi and Bronchioles - Anatomy & Physiology|bronchioles]] have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.

**'''Alveoli''': These 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.

 

===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 [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].

===Alveolar Sacs===

These are rotunda-like areas on the end of each alveolar ducts which are usually present in clusters.

===Alveoli===

These 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.

==Function==

==Function==