This unit contains sections on fetal pig anatomy, human respiratory anatomy, ventilation, spirometry and control of respiration. Topics discussed in the fetal pig anatomy section include the head, oral cavity, trachea, bronchial tubes, and lungs. One demonstration pig can be prepared for the entire class or individual students can dissect their own pig. The human respiratory anatomy section discuses the respiratory structures of the head and oral cavity and the trachea, bronchial tubes and lungs. Exercises in this section include dissection of the fetal pig head , oral cavity, fetal pig trachea, bronchial tubes, the lungs and the microscopic examination of lung tissue. The ventilation section discusses inspiration, expiration, pressure relationships and breathing movements. Exercises in this section include the functional lung model, and breathing movements. The spirometry section discusses lung volumes and lung capacities. Exercises in this section include measuring lung volume and capacity. The section on control of respiration includes an exercise on measuring respiration rate. The unit concludes with a set of summary laboratory questions emphasizing the main concepts of the unit.