The Pulmonary System
Upper and lower pulmonary structures, bronchial/systemic circulation, and gas exchange at the lungs and tissue cell levels comprise the pulmonary system. These anatomical structures collaborate to achieve two primary goals: oxygen delivery and carbon dioxide removal (Nurseslabs.com, 2017 & Tortora & Derrickson, 2014).
The nose and pharynx are examples of upper structures. The pharynx comprises three parts: the nasopharynx, oropharynx, and laryngopharynx. These structures filter, humidify, and warm the outside air while equalizing ear pressure (Nurseslabs.com, 2017 & Tortora & Derrickson, 2014).
The lower structures are the larynx, trachea, carina, bronchi, bronchioles, and alveoli. The primary function of these structures is to transport oxygen and carbon dioxide from the alveoli, where gas exchange occurs. Would you believe that the lungs contain approximately 300 million alveoli, which, if opened and laid out flat, would cover 900 square feet, the size of an apartment!
Except for the area around the mediastinal space, the lungs encircle the entire thoracic cavity. The mediastinal space is occupied by the heart, major blood vessels, bronchi, and esophagus, among other organs. Tortora and Derrickson (2014) and Nurseslabs.com (2017)
The lungs are responsible for two primary functions: ventilation and diffusion.
• Ventilation refers to air exchange between the atmosphere and the alveoli.
• Diffusion: the exchange of oxygen and carbon dioxide across the respiratory membrane from one concentration to another.
Tortora and Derrickson (2014) and Nurseslabs.com (2017)
The right lung is divided into three lobes and accounts for approximately 55% of lung activity.
The left lung is divided into two lobes and accounts for approximately 45% of lung activity (Nurseslabs.com, 2017; Tortora & Derrickson, 2014).
Pulmonary circulation is distinct because veins rather than arteries transport oxygenated blood. The pulmonary artery receives deoxygenated blood from the heart and returns oxygenated blood via the pulmonary vein (Nurseslabs.com, 2017 & Tortora & Derrickson, 2014).
Have you ever wondered why the oxygen saturation in the left atrium and left ventricle is not 100%? The answer is found in bronchial circulation, where deoxygenated blood is removed by both bronchial and pulmonary veins. Because of the mixing of oxygenated and unoxygenated blood in the pulmonary vein, the oxygen saturation of blood on the left side of the heart is never 100% (Nurselabs.com, 2017; Tortora & Derrickson, 2014).
The diaphragm contracts and moves downward, forcing air into the lungs during the inhalation phase of respiration. This movement accounts for 70% of tidal volume. The movement of the external and internal intercostal muscles, abdominals, and accessory muscles in the neck contributes to the remaining 30% of tidal volume (Nurseslabs.com, 2017 & Tortora & Derrickson, 2014).
The Pulmonary System
Part 1 compare the pathophysiology of asthma and COPD.
- How are they similar?
- How are they different?
How does the shadow health lab modules help students learn about the pulmonary system