The respiratory system allows the body to take in oxygen and remove carbon dioxide — two essential processes that keep every cell alive. For nursing students, understanding respiratory anatomy and function is crucial for clinical practice and exams. This guide breaks down the respiratory system into simple, student-friendly notes.
What Is the Respiratory System?
The respiratory system is the group of organs responsible for breathing. It includes the airways, lungs, and respiratory muscles that work together to deliver oxygen to the blood and remove carbon dioxide from the body.
Key Functions:
- Gas exchange (oxygen in, carbon dioxide out)
- Maintaining pH balance
- Producing sound (voice)
- Filtering, warming, and humidifying air
Upper vs Lower Respiratory Tract
Upper Respiratory Tract:
- Nose
- Nasal cavity
- Pharynx
- Larynx
Lower Respiratory Tract:
- Trachea
- Bronchi
- Bronchioles
- Lungs
- Alveoli
Tip for nursing students:
Upper = entry and filtering
Lower = gas exchange and ventilation
Airway Anatomy
Trachea:
A tube supported by cartilage rings that keeps the airway open. It splits into the right and left bronchi.
Bronchi & Bronchioles:
Bronchi divide into smaller bronchioles that distribute air throughout the lungs.
Alveoli:
Tiny air sacs where gas exchange happens. Each alveolus is surrounded by capillaries that allow oxygen to diffuse into the blood and carbon dioxide to diffuse out.
Remember:
🫁 “Alveoli = gas exchange”
How Breathing Works (Ventilation)
Inhalation (Inspiration):
- Diaphragm contracts and moves downward
- Ribcage expands
- Lung volume increases
- Air is pulled in
Exhalation (Expiration):
- Diaphragm relaxes
- Ribcage moves downward
- Lung volume decreases
- Air is pushed out
This process is controlled by the respiratory centre in the brainstem.
Gas Exchange Explained
Gas exchange happens in the alveoli:
- Oxygen moves from the alveoli → into the bloodstream
- Carbon dioxide moves from the blood → into the alveoli
- This works by diffusion (movement from high concentration to low concentration)
Key term:
👉 Ventilation-Perfusion (V/Q) Match
This describes how well air flow matches blood flow — important in conditions like PE or pneumonia.
Common Respiratory Assessments for Nurses
- Respiratory rate
- Oxygen saturation (SpO₂)
- Work of breathing
- Lung sounds (crackles, wheezes, stridor)
- Sputum colour/consistency
- Chest expansion symmetry
- Use of accessory muscles
Summary Table
| Topic | Key Points |
|---|---|
| Main Function | Gas exchange |
| Lower Tract | Lungs, bronchi, bronchioles, alveoli |
| Gas Exchange | Happens in alveoli via diffusion |
| Inhalation | Diaphragm contracts, lungs expand |
| Nursing Assessments | RR, SpO₂, lung sounds |