What are the structures of the respiratory system from the nasal passage through to the alveoli?

The path that oxygen takes through the respiratory system is as follows:

Mouth or Nostrils of the Nose → Nasopharynx → Oral Pharynx → Larynx → Trachea → Lungs (Right and Left Bronchi → Bronchioles → Alveoli)

The functions of each part of the respiratory system have been identified below:

Mouth or Nostrils

Air enters the body via the mouth or nostrils of the nose.

Pharynx

The pharynx is the “throat” that connects the mouth or nostrils with the esophagus and larynx.

Larynx

The larynx is located between the trachea and pharynx. As part of the respiratory system, the larynx protects the trachea from food aspiration. Food aspiration occurs when an object, such as food or beverage, is inhaled into the lungs.

Trachea

The trachea is sometimes referred to as the “windpipe”. The trachea is the tube that may be felt in your neck. It is rimmed with rings of cartilage. It is the passageway of air into the lungs. Small hairs line the trachea. These small hairs act as a filter that prevents dust or other debris from entering the lungs.

Lungs

The lungs pass oxygen into the body and push carbon dioxide out of the body. The lungs are composed of the bronchi, bronchioles, and alveoli. Each of these structures and their functions are identified below.  

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  Bronchi: The right and left bronchi are the two main branches into the lungs.


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  Bronchioles: Bronchioles feed air into the alveoli sacs.


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  Alveoli sacs: Gas exchange occurs between the alveoli sacs and small capillaries. It is here that oxygen is delivered from the lungs to the bloodstream. The oxygen attaches to the hemoglobin of red blood cells. The red blood cells then delivers the oxygen to the cells. The oxygen is then used during cellular respiration in order to make energy in the form of adenosine triphosphate (ATP).

Although not involved in the delivery of air into the body, the diaphragm is also a part of the respiratory system. The diaphragm is a dome-shaped muscle that lies just below the lungs. As the diaphragm contracts, it moves downward. Thus, the chest cavity expands and air is able to move into the lungs. As the diaphragm relaxes, it pushes air out of the lungs.