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Anatomy of Your Child’s Respiratory System

The respiratory system carries air into and out of the lungs. When your child breathes in, oxygen-rich air flows into the lungs. This oxygen is sent to all the body’s cells to use for energy and growth. When your child breathes out, waste gases (carbon dioxide) flow out.

How breathing works

Anatomy of bronchiole and alveoli.

Breathing in is called inspiration. When your child breathes in, air fills the airways in the lungs. Oxygen-rich air reaches the balloon-like air sacs at the end of the airways. These sacs are called alveoli. Oxygen passes into the blood vessels that surround the sacs. The blood then carries the oxygen to all parts of the body. As the body uses oxygen, it produces carbon dioxide (a waste gas), which the blood carries back to the lungs. When your child breathes out, carbon dioxide leaves the body through the airways, windpipe, and mouth or nose. Breathing out is called expiration.

Parts of the respiratory system

A child’s respiratory system is similar to an adult’s. However, some structures differ in size or position. For example, an infant’s tongue takes up more space in the mouth than an adult’s. And an infant’s larynx is located in a higher position in the neck than it is in an adult.

Toddler with head turned to side showing upper and lower respiratory system.

  • The mouth and nose are the openings through which air enters and exits the body.

  • Sinuses are air-filled chambers within the bones of the face. They help keep the nose moist and free of dust and bacteria.

  • The pharynx is the cavity behind the mouth.

  • The larynx is the upper part of the windpipe, which contains the vocal cords.

  • The windpipe (trachea) provides a pathway for air to enter and exit the lungs.

  • The lungs are a pair of organs made of spongy tissue. They have five sections, or “lobes,” three in the right lung and two in the left. The lungs allow the body to receive oxygen and get rid of carbon dioxide.

  • Bronchioles (airways) are stretchy “branches” that transport air throughout the lungs. Bands of muscles surround each bronchiole. Bronchioles get smaller as they go deeper into the lungs.

  • Alveoli are clusters of balloon-like air sacs at the ends of the airways.

  • Blood vessels are tubes that carry blood to the lungs and throughout the body. Tiny blood vessels surround the air sacs, allowing an exchange of oxygen and carbon dioxide.

  • The pleural space is an area between the lungs and chest wall, lined on both sides by tissue called pleura.

  • The diaphragm is a muscle in the abdomen that helps with breathing.

  • Mucus is a sticky substance made by cells in the lining of the airways. It traps dust, smoke, and other particles from air breathed in.

  • Cilia are tiny hairs on the cells of the airway lining that are coated with sticky mucus. They trap germs and foreign particles that enter from air breathed in and sweep them up to the nose or  mouth. From there, mucus gets swallowed, sneezed, or co

    ughed out.


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