Describe the structural and functional features of the upper and lower respiratory systems? Are any the same?
The human respiratory system is divided into the upper respiratory system consisting of the nose, nasopharynx, hypopharynx, larynx and trachea, and the lower respiratory system, the lungs.
The upper respiratory system is primarily a conduit for the air. The system is also responsible for cleaning, warming and humidifying inhaled air. It also is a conduit for air that is exhaled from the lungs.
The nose has fibers or cilia that help remove larger dust particles from inhaled air. The plates in the nose covered with mucosa help warm and humidify the air.
The nasopharynx participates in the warming and humidification, and conducts the air to the larynx. The larynx is the voice box. Speech is made possible by use of the vocal cords in the larynx during exhalation.
The trachea transports the air to the major bronchi. The bronchi divide into smaller and smaller branches, finally becoming tiny bronchioles that end in the alveolar sacs of the lungs. It is in the alveoli that respiration occurs. Respiration is the absorption of oxygen into the blood stream, and excretion of carbon dioxide from the blood into the exhaled air.
In addition to the air passages and lungs (primary respiratory system), the sinuses in the skull are considered by some to be accessory respiratory organs. They do not participate in gas exchange but are important during speech where they provide the proper quality of the human voice. The sinuses, being hollow structures within the skull and facial skeleton, also add lightness to the head.
In summary, the upper respiratory system is a conduit that cleanses, warms and humidifies and transports inhaled air, and provides as pathway for exhaled air as well. The lower respiratory system consists of the lungs themselves where gas exchange takes place.