Skip to main content
Medicine LibreTexts

20: Respiratory System

  • Page ID
  • The respiratory system consists of specific organs and structures used for the process of respiration in an organism. The respiratory system is involved in the intake and exchange of oxygen and carbon dioxide between an organism and the environment.

    • 20.1: Introduction to the Respiratory System
      You may be surprised to learn that although oxygen is a critical need for cells, it is actually the accumulation of carbon dioxide that primarily drives your need to breathe. Carbon dioxide is exhaled and oxygen is inhaled through the respiratory system, which includes muscles to move air into and out of the lungs, passageways through which air moves, and microscopic gas exchange surfaces covered by capillaries.
    • 20.2: Organs and Structures of the Respiratory System
      The major organs of the respiratory system function primarily to provide oxygen to body tissues for cellular respiration, remove the waste product carbon dioxide, and help to maintain acid-base balance. Portions of the respiratory system are also used for non-vital functions, such as sensing odors, speech production, and for straining, such as during childbirth or coughing .
    • 20.3: The Lungs
      A major organ of the respiratory system, each lung houses structures of both the conducting and respiratory zones. The main function of the lungs is to perform the exchange of oxygen and carbon dioxide with air from the atmosphere. To this end, the lungs exchange respiratory gases across a very large epithelial surface area—about 70 square meters—that is highly permeable to gases.
    • 20.4: The Processes of the Respiratory System
      The processes of the respiratory system follow oxygen from its origin in the air you inhale to its use by cells of the body to convert glucose to cellular energy in the form of adenosine triphosphate (ATP). Since the conversion of glucose to ATP produces carbon dioxide as a waste, carbon dioxide originates at the cells of the body and takes the same journey in reverse to be eliminated form the body when you inhale. The processes of the respiratory system are pulmonary ventilation, external respi
    • 20.5: Embryonic Development of the Respiratory System
      Development of the respiratory system begins early in the fetus. It is a complex process that includes many structures, most of which arise from the endoderm. Towards the end of development, the fetus can be observed making breathing movements. Until birth, however, the mother provides all of the oxygen to the fetus as well as removes all of the fetal carbon dioxide via the placenta.