Fundamentals · chapter 19 · Oxygenation and Perfusion
Respiratory System
The 13 things this section of the textbook says that you are most likely to be asked about — quoted word for word, not retold. Then 4 practice questions with the reasoning.
Key points
Respiratory purpose
The primary purpose of the respiratory (or pulmonary) system is gas exchange, which is necessary to support human life. The gas exchange happens where the capillaries and alveoli meet, with a very thin membrane between them—the capillary-alveolar bed (or membrane).
Upper airway boundary
The upper airway extends from the sinuses and nose through the trachea to the carina, where the airway bifurcates into left and right bronchi and continues into the lungs.
Tracheal patency and clearance
A combination of cartilage and connective tissue gives the trachea its shape and maintains it open for the passage of air. Cilia line the trachea, continuing the process of trapping foreign objects and allowing for their removal, in the same fashion as in the higher structures of the upper airway.
Lower airway branching
The bronchi are the major structures of the lower airway and begin with the bifurcation of the right and left mainstem bronchi, which enter into the right and left lung, respectively. Subsequently, the mainstem bronchi continue paths through the lungs as the primary, secondary, and tertiary bronchi, becoming smaller, and branching further throughout the lungs.
Bronchiole airflow control
These continue to their smallest form as terminal bronchioles; at this point, the airway is no longer supported by cartilage, and the muscles comprising the walls can dilate and constrict to control the flow of air.
Alveolar-capillary exchange
These clusters of alveoli are where the most common type I alveolar cells and the smallest capillaries of the bloodstream exchange gases (primarily O 2 and CO 2) through a very thin alveolar-capillary membrane (Ball et al., 2023).
Lung lobe anatomy
The right and left lungs are slightly different in structure: the left lung is shaped to include the cardiac notch, which provides space for the heart. The left lung has two lobes: upper and lower; the right lung contains three lobes: upper, middle, and lower.
Acid-base compensation
By increasing the rate and depth of respirations, excess CO 2 is released through exhalation, and an acidic pH (less than 7.35) may be improved. An alkalotic pH (over 7.45) may be corrected by shallow, slow breaths, allowing the accumulation of CO 2 to bring pH closer to normal.
Oxygenation processes
Oxygenation involves interactions between the respiratory and cardiovascular systems, including air movement through the lungs, where O 2 and CO 2 are exchanged through the alveoli and capillaries as the respiratory and circulatory systems connect and interact at the alveolar-capillary bed. Physiological processes involved include ventilation (the movement of air in and out of the lungs) and perfusion.
Inspiration mechanics
The part of the respiratory cycle whereby the diaphragm and intercostal muscles contract, which enlarges the space within the thorax, is called inspiration. This enlargement lowers the pressure within the alveoli, and air flows into the lungs.
Cough and deep breathing
Deep breaths often inspire coughing, and coughing causes deep breaths, which fosters continued production and release of surfactant and prevention of atelectasis (alveolar collapse). For this reason, patients are encouraged to cough and deep breathe when inspiration is limited.
Respiratory assessment
In addition to the respiratory rate, nursing assessment of the respiratory system also includes auscultation of breath sounds and observation of depth and regularity of breathing, symmetry, whether the patient relies on the use of accessory muscles to breathe, their desired position, and how they breathe (e.g., pursed lips, gasping, apneic pauses), as well as apparent anxiety.
Pulse oximetry and ABGs
A noninvasive device called a pulse oximeter measures saturation of hemoglobin with O 2 and can be a valuable respiratory assessment tool. Arterial blood gas (ABG) testing offers important data in some circumstances of respiratory compromise and potential failure, but ABGs are invasive and typically considered painful.
Terms to know
- surfactant
- A phospholipid substance that prevents the collapse of alveoli by reducing surface tension is called surfactant.
- compliance
- Normal, healthy lungs are supple and yield in size and shape to the demands of respiration, including compliance, the ability to accommodate deep and shallow breaths, and elastic recoil, or the ability to bounce back to normal size and shape after the expansion of inhaling, during exhalation.
- ventilation
- Physiological processes involved include ventilation (the movement of air in and out of the lungs) and perfusion.
- inspiration
- The part of the respiratory cycle whereby the diaphragm and intercostal muscles contract, which enlarges the space within the thorax, is called inspiration.
- respiration
- The term respiration is a rather general term, often synonymous with the word breathing.
- Diffusion
- Diffusion is a transport process that involves molecular movement driven by a concentration gradient.
- Perfusion
- Perfusion, as previously defined, is associated with the circulatory system and is evidenced by the cardiovascular system’s delivery of O 2 and nutrients to body tissues.
- carina
- The carina is the border of the upper and lower airways.
Practice questions
Stuck on select-all-that-apply? How to take them one option at a time.
The graded version needs JavaScript. Every question is below anyway, with the answer and why.
Every question here, with the answer
A nurse is suctioning an intubated patient through an inline suction catheter. As the catheter is advanced, the patient begins coughing. What is the nurse’s best action?
- Increase the suction pressure because coughing indicates retained secretions.
- Advance the catheter farther to ensure the lower airway is reached.
- Stop suctioning permanently because coughing means suctioning is contraindicated.
- Note that the catheter may have touched the carina and avoid advancing that far again.
Answer: Note that the catheter may have touched the carina and avoid advancing that far again.
The section explains that the carina is sensitive and touching it causes coughing, meaning the catheter has gone too far. The safest nursing action is to avoid stimulating that area again rather than advancing farther or assuming suctioning must stop permanently.
An older adult patient with hearing impairment is learning to use an incentive spirometer. Which nursing actions are appropriate? Select all that apply.
- Use gestures or dramatic movements to show deep inhalation through the mouthpiece.
- Consider marking a goal line on the device for the patient.
- Teach the patient to blow forcefully into the mouthpiece because it is attached to a strawlike hose.
- Demonstrate the correct use of the incentive spirometer.
- Ask the patient to provide a return demonstration.
Answer: Use gestures or dramatic movements to show deep inhalation through the mouthpiece., Consider marking a goal line on the device for the patient., Demonstrate the correct use of the incentive spirometer., Ask the patient to provide a return demonstration.
The section emphasizes that patients with hearing or cognitive impairment may need demonstration, gestures, and a return demonstration so the nurse can assess understanding. Blowing into the device is specifically described as a common incorrect assumption; the correct action is inhaling deeply through the mouthpiece.
A patient asks why swallowing problems can increase concern for material entering the airway. Which explanation by the nurse is most accurate?
- The epiglottis helps protect the trachea by preventing food or fluid from flowing into it.
- The carina closes the esophagus during swallowing to prevent aspiration.
- The true vocal cords move food into the esophagus during swallowing.
- The nasal turbinates close during swallowing to block food from the lungs.
Answer: The epiglottis helps protect the trachea by preventing food or fluid from flowing into it.
The epiglottis is described as the structure that protects the trachea during swallowing by preventing food or fluid from entering it. The other options assign this protective swallowing function to structures not described as performing it in the section.
A patient has limited inspiration and is being taught ways to support alveolar inflation and reduce the risk of alveolar collapse. Which instructions align with the section? Select all that apply.
- Use the incentive spirometer with slow, deep breaths.
- Cough and deep breathe as instructed.
- Understand that deep breaths help support production and release of surfactant.
- Take only shallow breaths to allow CO2 to accumulate.
- Avoid coughing because it interferes with surfactant production.
Answer: Use the incentive spirometer with slow, deep breaths., Cough and deep breathe as instructed., Understand that deep breaths help support production and release of surfactant.
The section connects deep breaths, coughing, surfactant production and release, and prevention of atelectasis. It also states that patients are encouraged to cough and deep breathe when inspiration is limited and that incentive spirometer use involves slow, deep breaths.
Where every quote comes from
Section 19.1 Respiratory System of Fundamentals of Nursing by Christy Bowen, Lindsay Draper, Heather Moore, OpenStax, 2024. Read the whole section free at openstax.org.
The textbook is licensed under CC BY-NC-SA 4.0. This page quotes it word for word and adds the headings, the order and the practice questions; references to the book's figures and stray spaces left by its formatting are removed. The page is shared under the same licence. Nothing here is sold.