Anatomy of the Respiratory System in Children

Respiration is the act of breathing in and breathing out. When you inhale, you take in oxygen from the air. When you exhale, you give off carbon dioxide.

There are receptors in the body that sense oxygen and carbon dioxide levels. These receptors trigger the brain to begin breathing. If there is a problem with either the brain or the receptors, the respiratory system may not be able to perform as needed.

The respiratory system is made up of the organs that bring in oxygen and release carbon dioxide. It is made of the:

• Nose
• Mouth
• Throat (pharynx)
• Voice box (larynx)
• Windpipe (trachea)
• Airways (bronchi)
• Lungs

The upper respiratory tract includes the following:

• Nose and mouth
• Nasal cavity
• Sinuses

The lower respiratory tract includes the following:

• Voice box (larynx)
• Epiglottis (a flap that covers the windpipe when eating)
• Windpipe (trachea)
• Lungs
• Airways (bronchi and bronchioles)
• Air sacs (alveoli)

Muscles that support breathing include the following:

• Diaphragm: strong, dome shaped muscle below the lungs. It is the main muscle for inhaling and exhaling air. When the diaphragm is tight and flat, the chest expands and air comes into the lungs. When the diaphragm relaxes, the air in the lungs is forced out.
• Neck muscles: also called accessory muscles, help to expand the upper chest when you take in a breath.
• Intercostal muscles: found between the ribs. These muscles help move the chest in and out when you breathe or cough.
• Abdominal muscles: found in the stomach and are used for deep breathing and coughing.

The lungs take in oxygen, which the body's cells need to live and carry out their normal functions. They 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 part of the body between the base of the neck and diaphragm). The lungs are enveloped in a membrane called the pleura and separated from each other by the mediastinum: This area contains the following:

• Heart and its large vessels
• Trachea (windpipe)
• Esophagus
• Thymus gland
• Lymph nodes

The right lung has 3 lobes. The left lung has 2 lobes. When you breathe, the air:

• Enters the body through the nose or the mouth. The nose removes dust and dirt from the air. Warmth and moisture go into the air before it travels to the lungs.
• 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
  • Then into even smaller tubes called bronchioles
  • Bronchioles end in tiny air sacs called alveoli. The sacs are surrounded by tiny blood vessels called capillaries. Inhaled oxygen enters the alveoli and then is sent to the blood. Blood from the veins also enters the alveoli. Carbon dioxide is then removed from the blood and sent back out of the body when we exhale.