The anatomy of a child’s lung is very similar to that of an adult. The lungs are a pair of air-filled organs consisting of spongy tissue called lung parenchyma. Three lobes or sections make up the right lung, and two lobes make up the left lung. The lungs are located on either side of the thorax or chest and function to allow the body to receive oxygen and get rid of carbon dioxide, a waste gas from metabolism. To understand the anatomy of the pediatric lung and lung disease in children, it is important to take a look at the entire respiratory system.
The anatomy of the pediatric respiratory system can be divided into 2 major parts:
- Pediatric Airway Anatomy: Outside of the thorax (chest cavity) includes the supraglottic (epiglottis), glottic (airway opening to the trachea), and infraglottic (trachea) regions. The intrathoracic airway includes the trachea, two mainstem bronchi, bronchi and bronchioles that conduct air to the alveoli.
- Pediatric Lung Anatomy: Lung anatomy includes the lung parenchyma are subdivided into lobes and segments that are mainly involved in the gas exchange at the alveolar level.
The Child Respiratory System
- Mouth and Nose
- Pharynx – cavity located behind the mouth
- Larynx – part of the windpipe that contains the vocal cords
- Trachea – also referred to as the windpipe, conducts into and out of the lungs
- Lungs – a pair of spongy air filled organs.
- Bronchial tubes – passages that carry the air and divide and branch as the travel through the lungs
- Bronchioles – tiny passages surrounded by bands of muscle that transport air throughout the lungs. Bronchioles continue to divide into smaller and smaller units until they reach microscopic air sacs called alveoli
- Lung Alveoli – clusters of balloon-like air sacs
- Lung Interstitium – Thin layer of cells between alveoli that contain blood vessels and help support the alveoli
- Pulmonary Blood Vessels – tubes that carry blood to the lungs and throughout the body
- Lung Pleura – thin tissue that covers the lungs
- Lung Pleural Space – area lined with a tissue called pleura and located between the lungs and the chest wall
- Diaphragm – a muscle in the abdomen that assist with breathing
- Lung Mucus – sticky substance that lines the airways and traps dust and other particles inhaled
- Lung Cilia – microscopic hair-like structures that extend from the surface of the cells lining the airway. Covered in mucus, cilia trap particles and germs that are breathed in.
Anatomy of a Child’s Lung and the Breathing (Inspiration and Expiration)
Breathing is the process that moves air in (inspiration) and moves air out (expiration) of the lungs through inhalation and exhalation. As the lungs expand and contract, oxygen rich air is inhaled and carbon dioxide is removed. Breathing begins at the mouth and nose where air is inhaled. The air travels to the back of the throat, into the trachea and then divides into the passages known as the bronchial tubes. The bronchial tubes continue to divide as the go deeper into the lungs and the air is carried to the alveoli. Oxygen passes through the walls of the alveoli and into the blood vessels that surround these tiny sacs. Once oxygen enters the blood vessels, it is carried out of the lungs and to the heart where it can be pumped throughout the body to other organs and tissue. When the cells use oxygen, they produce a waste product called carbon dioxide. The carbon dioxide is carried by the blood vessels back to the lungs. Through exhaling, the carbon dioxide is carried back out of the lungs where it can exit through the mouth or nose.
Differences in Pediatric Pulmonary Anatomy
While the basic anatomy of the pediatric lung and the adult lung are the same, there are some important differences that should not be overlooked. These differences can increase the occurrence and severity of lung disease and respiratory issues in young children and impact treatments and techniques that are most effective.
- The ribs in infants and young children are oriented more horizontally than in adults and older children lessening the movement of the chest.
- Rib cartilage is more springy in children making the chest wall less rigid. This can allow the chest wall to retract during episodes of respiratory distress and decrease tidal volume.
- The intercostal muscles that run between the ribs are not fully developed until a child reaches school age. This can make it difficult to lift the rib cage especially when lying flat on the back.
- The back of a child’s head is typically larger than in adults. This can cause the neck to flex when a child is lying on his or her back and result in a partially obstructed airway.
- Infants and children tend to have a proportionally larger tongue in relation to the space in the mouth.
- Younger children are typically nose breathers.
- The internal diameter of the airways in a child is smaller. Any inflammation or obstruction may cause more severe distress.
- In general, pediatric airways are smaller, less rigid, and more prone to obstruction.
- Children also have higher respiratory rates than adults making them more susceptible to agents in the air.
The anatomy of a child’s lungs and other components of the pulmonary (respiratory) system make treating pediatric lung disease a very specialized practice. Children are unique and affective treatments and approaches need to be as well. For more information about pediatric respiratory disease please submit an online appointment request or contact the office of Dr. Peter N. Schochet.