Anatomy of the Respiratory System

Respiration

Respiration is the act of breathing:

  • Inhaling (inspiration). The act of breathing in oxygen.

  • Exhaling (expiration). The act of breathing out carbon dioxide.

Respiratory system

Illustration of the human respiratory system

The respiratory system is made up of the organs involved in the exchange of oxygen and carbon dioxide, and consists of the:

  • Nose

  • Mouth

  • Pharynx (throat)

  • Larynx (voice box)

  • Trachea (windpipe)

  • Bronchi (large airways)

  • Lungs

The upper respiratory tract includes the:

  • Nose

  • Nasal cavity

  • Sinuses

  • Larynx

  • Trachea

The lower respiratory tract includes the:

  • Lungs

  • Bronchi and bronchioles

  • Alveoli (air sacs)

Lungs

The lungs take in oxygen, which the body's cells need to live and carry out their normal functions. The lungs also get rid of carbon dioxide, a waste product of the cells.

The lungs are a pair of cone-shaped organs made up of spongy, pinkish-gray tissue. They take up most of the space in the chest, or the thorax.

The lungs are surrounded by a membrane called the pleura.

The lungs are separated from each other by the mediastinum, an area that contains the following:

  • Heart and its large vessels

  • Trachea (windpipe)

  • Esophagus

  • Thymus gland

  • Lymph nodes

The right lung has three sections, called lobes. The left lung has two lobes. When you breathe, the air:

  • Enters the body through the nose or the mouth

  • Travels down the throat through the larynx (voice box) and trachea (windpipe)

  • Goes into the lungs through tubes called main-stem bronchi:

    • One main-stem bronchus leads to the right lung and one to the left lung

    • In the lungs, the main-stem bronchi divide into smaller bronchi

    • And then into even smaller tubes called bronchioles

    • Bronchioles end in tiny air sacs called alveoli

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