Anatomy of Respiratory System II: Lower Respiratory Tract

The lower respiratory tract comprises the larynx, trachea, bronchial tree, alveoli, lungs, and pleurae.

The larynx, positioned between the pharynx and the trachea, houses the epiglottis, vocal cords, and glottis.

The trachea, or windpipe, transports air to the lungs and branches into the right and left bronchi.

The right main bronchus further divides into three lobar bronchi, whereas the left main bronchus divides into two.

Each lobar bronchus branches into segmental bronchi and then into smaller bronchioles.

The bronchioles lead to the alveolar ducts and alveoli. These alveoli are tiny sac-like structures serving as the primary site for gas exchange.

Next, the lungs, elastic structures housed within the thoracic cage, are divided into lobes: the right lung comprises upper, middle, and lower lobes, while the left lung comprises upper and lower lobes.

Finally, the pleurae are double-layered serous membranes enveloping the lungs.

It features two main layers: the visceral pleura, which envelops the lungs, and the parietal pleura, which lines the thoracic cavity, including the diaphragm and the lateral wall of the mediastinum.