The conducting portion of the respiratory system includes all, except
a. alveoli. b. trachea. C. larynx. d. nasal cavity. e. bronchi.
The correct answer and explanation is:
The correct answer is a. alveoli.
The conducting portion of the respiratory system consists of all the structures that air passes through to reach the alveoli. These include the nasal cavity, pharynx, larynx, trachea, bronchi, and bronchioles. Their primary function is to filter, warm, and moisten the air before it reaches the gas exchange surfaces. This portion does not participate directly in gas exchange but is essential for preparing air to reach the respiratory zones, where gas exchange occurs.
The alveoli, on the other hand, are part of the respiratory portion of the respiratory system. They are the tiny air sacs where the exchange of oxygen and carbon dioxide takes place between the air in the lungs and the blood in the capillaries. The walls of the alveoli are very thin and are covered with a network of capillaries that allow gases to diffuse across the membrane.
To elaborate on the structures of the conducting portion:
- Nasal cavity: The air enters through the nose, where it is filtered by mucus and hairs, and moistened and warmed.
- Pharynx: A passageway that connects the nasal cavity to the larynx and serves as a conduit for air.
- Larynx: Contains the vocal cords and serves as a passageway for air to the trachea.
- Trachea: A tube that carries air from the larynx to the bronchi. It is lined with ciliated cells that help move mucus and trapped particles out of the lungs.
- Bronchi and bronchioles: The bronchi divide into smaller bronchi and then into bronchioles, which continue to direct air toward the alveoli.
Thus, while the alveoli are crucial for respiration, they are not part of the conducting portion, but rather the respiratory portion, which is responsible for gas exchange.