Measurable Outcomes

• Understand and identify the anatomical structures of the respiratory system on available models.
• Deduce the pathway of air through the respiratory system.
• Determine the pathway of pulmonary circulation.
• Identify the various muscles involved in respiration.
• Recognize the hallmarks of lung histology.
• Demonstrate an adequate understand of the material in this section.

Background

The respiratory system is responsible for the gas exchange of oxygen and carbon dioxide. The main specialized organs of this process are the lungs which house clusters of sac-like structures known as alveoli. There are from 480 to 790 million alveoli which increase the efficiency of gas exchange by increasing surface area to around 118m² in men and 91m² in women. The respiratory system consists of the nasal cavity, pharynx, larynx, trachea, lungs, bronchi, bronchioles, and alveoli, along with their accessory structures. These structures are divided into the upper and lower respiratory systems, with the lower portion beginning at the larynx. The primary function of this system is to exchange oxygen and carbon dioxide between the body and the environment. Functionally, the respiratory system can be divided into the conducting zone, terminating at the terminal bronchioles; then air flows into the respiratory zone, where the actual gas exchange occurs.

Though we view each system individually in this lab, it is important to keep in mind that all organ systems overlap and work together in such a way that scientist are constantly discovering new connections. One such example is the nose. Not only is it the primary entrance and exit for respiration, but it also contains the olfactory epithelium, the primary structure of one of the special senses, olfaction. Likewise, the pharynx is a structure shared by both the respiratory and digestion systems.

Although both lungs functionally participate in respiration, they differ physically in various ways. The right lung is shorter and wider than the left lung, and the left lung occupies a smaller volume than the right. Another distinction between the two lungs is that the left lung contains the cardiac notch, which makes space for the heart. Furthermore, whereas the right lung has three lobes, the left lung has only two.

Though not visible on every model, each lung is surrounded by the pleura, which consists of two layers called the visceral and parietal pleurae. They are important because they lubricate the lungs and reduce friction during inhalation and exhalation.

Vocabulary for Respiratory System can be found on page(s) 169.