Respiratory System
Disease Information
In-Depth
The upper respiratory tract includes the:
- nose
- nasal cavity – a large, fluid-filled space above and behind the nose
- pharynx - the part of the neck and throat right behind the mouth and nasal cavity
- larynx - also known as the “voicebox,” this is a cylindrical grouping of cartilage, muscles, and soft tissue which contains the vocal cords
- trachea - also known as the “windpipe;” a tube that allows air to pass to the bronchi in the lungs
- ethmoidal, frontal, and maxillary sinuses – sinuses are cavities, or air-filled pockets, near the nasal passage. They help the nose filter the air by producing mucus, which traps dust and bacteria before they can reach the lungs. The sinuses include:
|
|
Location |
Development |
|---|---|---|
|
ethmoid sinus |
inside the face, around the bridge of the nose |
present at birth and continues to grow |
|
maxillary sinus |
inside the face, around the cheeks |
present at birth and continues to grow |
|
frontal sinus |
inside the face, in the area of the forehead |
does not develop until around 7 years of age |
|
sphenoid sinus |
deep in the face, behind the nose |
does not develop until adolescence |
The lower respiratory tract includes the:
- Bronchi – also known as “airways.” The trachea splits into the two main-stem bronchi, one leading directly into each lung. In each lung, the main-stem bronchi divide into smaller bronchi called bronchioles that end in tiny air sacs called alveoli.
- Lungs - pair of cone-shaped organs made up of spongy, pinkish-gray tissue that take up most of the space in the chest. Lungs take in oxygen, which cells need to live and carry out their normal functions, and get rid of carbon dioxide, a waste product of the body's cells.
- Alveoli (air sacs) –tiny sacs in the lungs that expand as they fill with air, and then contract as they expel carbon dioxide. Each human lung has about 300 million alveoli.
The lungs are enveloped in a membrane called the pleura, and separated from each other by the mediastinum, an area that contains the following:
- heart and its large vessels
- trachea
- esophagus
- thymus
- lymph nodes
What happens when you breathe?
When we breathe, the air:
- enters the body through the nose or the mouth. Some particles are filtered out through the nose hair and through the mucus produced by the sinuses
- travels down the throat through the larynx (voice box) and trachea (windpipe)
- goes into the lungs through tubes called main-stem bronchi
Are the left and right lungs identical?
Not quite - the right lung has three lobes (sections), and the left lung has two lobes.
What is surfactant?
An important part of your child’s lung development is the production of surfactant. This is a substance that consists of phospholipids and protein and is made by the cells in the small airways of your baby’s respiratory system.
When is surfactant produced?
Surfactant begins to be produced in the fetus at about 24 to 28 weeks of pregnancy, and it is found in amniotic fluid between 28 and 32 weeks. By about 35 weeks gestation, most babies have developed the right amount of surfactant.
Why is surfactant important?
Surfactant is normally released into the lung tissues where it helps lower surface tension in the airways, thus helping to keep the lung alveoli (air sacs) open. If your baby is premature, he may not have enough surfactant in his lungs and may have difficulty breathing.
