Bronchi and Bronchioles
Trachea → divides into 2 tubes called bronchi each bronchus carries air to the lung bronchi - similar in structure to the trachea → each bronchus branches repeatedly - which gives rise to many bronchioles (not supported by cartilage) bronchioles are fine tubes. → each bronchiole ends in a cluster of air sacs or alveoli.
Each lung lies in the pleural cavity lined by 2 transparent membranes (pleura) → inner pleuron covers the lung and other pleuron is in contact with the wall of the thorax. thin layer of lubricating fluid → in between 2 pleurals → allow easy glide between lungs and thorax.
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Alveoli (Air Sacs)
Gas exchange in the Alveoli → occur between the walls of the Alveoli
numerous alveoli → are found in the lungs → provide a VERY large surface area to volume ratio for gas exchange.
