
The wall of the nasal cavity has three bony projections, called the superior, middle, and inferior nasal conchae. The inhaled air enters into the nasal cavity, which is separated into left and right sections by the nasal septum. The major entrance and exit for the respiratory system is through the nose, via the nostrils. The major respiratory structures span the nasal cavity to the diaphragm. All of these conditions affect the gas exchange process and result in labored breathing and other difficulties. A variety of diseases can affect the respiratory system, such as asthma, emphysema, chronic obstruction pulmonary disorder (COPD), and lung cancer. The circulatory system transports gases from the lungs to tissues throughout the body and vice versa. 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. 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. For oxidative phosphorylation to occur, oxygen is used as a reactant and carbon dioxide is released as a waste product. This is because every cell in the body needs to run the oxidative stages of cellular respiration, the process by which energy is produced in the form of adenosine triphosphate (ATP). A typical human cannot survive without breathing for more than 3 minutes, and even if you wanted to hold your breath longer, your autonomic nervous system would take control. Really! See how long you can hold your breath as you continue reading…How long can you do it? Chances are you are feeling uncomfortable already.

General anesthesia – multifactorial, including loss of skeletal muscle tone and bronchoconstrictor tone.The ratio of physiologic dead space to tidal volume is usually about 1/3. Alveolar dead space is the volume of gas within unperfused alveoli (and thus not participating in gas exchange either) it is usually negligible in the healthy, awake patient. Anatomic dead space is the volume of gas within the conducting zone (as opposed to the transitional and respiratory zones) and includes the trachea, bronchus, bronchioles, and terminal bronchioles it is approximately 2 mL/kg in the upright position.

Physiologic or total dead space is the sum of anatomic dead space and alveolar dead space.

Dead space is the volume of a breath that does not participate in gas exchange.
