Final answer:
The lower respiratory tract includes the trachea, bronchi, bronchioles, and alveoli in the lungs where gas exchange occurs.
Step-by-step explanation:
The Lower Respiratory Tract
The lower respiratory tract consists of the trachea, bronchi and bronchioles, and the lungs. The trachea, or windpipe, extends from the larynx and bifurcates into the left and right bronchi as it reaches the lungs.
These bronchi branch repeatedly into smaller tubes called bronchioles and ultimately terminate in tiny air sacs known as alveoli.
The alveoli are crucial for gas exchange; this is where the air inhaled into the lungs exchanges oxygen and carbon dioxide with the blood in the capillaries that surround them.
Overall, the lower respiratory tract plays a pivotal role in the respiratory system by conducting air between the upper respiratory tract and the lungs and facilitating gas exchange.
The structure of the respiratory tract mirrors an inverted tree, with the trachea as the main trunk and the bronchi and bronchioles as the extensive branches, culminating in the alveoli—approximately 400,000,000 in human lungs.
Additionally, the lungs are protected by a double-layered pleural membrane which allows for smooth movement during respiration.