Domain 2.4Anatomy and Physiology

Respiratory System And Common Diseases

Last updated June 16, 2026

Overview

Welcome to your study guide for the Respiratory System! For a Medical Assistant, this system is central to daily clinical practice. You will frequently encounter patients presenting with coughs, shortness of breath, and infections.

Why This Matters:

  • Vital Signs: Respiratory rate and oxygen saturation (SpO2) are standard vital signs for every patient visit.
  • Testing: You will perform Pulmonary Function Tests (Spirometry) and administer TB skin tests.
  • Infection Control: Respiratory illnesses are often contagious (e.g., Flu, TB). Knowing how they spread protects you and other patients.
  • Emergency Recognition: You must be able to recognize the difference between a stable patient and one in respiratory distress.

This guide covers the anatomy of breathing, how to identify abnormal breath sounds, and the specific diseases you need to know for the certification exam.

1. Anatomy and Physiology of the Respiratory System

The primary function of this system is gas exchange: bringing Oxygen (O2) into the body and removing Carbon Dioxide (CO2).

A. The Airway Path

Air travels through the respiratory tract in a specific order.

  1. Nose/Nasal Cavity: Filters, warms, and moistens air. Cilia (hair-like projections) move mucus and trapped dust toward the throat to be swallowed.
  2. Pharynx (Throat): A shared pathway for air and food.
    • Nasopharynx: Top section (air only).
    • Oropharynx: Middle section (air and food).
    • Laryngopharynx: Bottom section.
  3. Larynx (Voice Box): Contains the vocal cords.
    • Epiglottis: The leaf-shaped flap that covers the larynx during swallowing to prevent food from entering the lungs.
  4. Trachea (Windpipe): The rigid tube kept open by C-shaped cartilage rings.
  5. Bronchi: The trachea splits into the right and left Mainstem Bronchi.
    • Clinical Note: The Right Bronchus is wider and more vertical, so inhaled foreign objects are more likely to lodge in the right lung.
  6. Bronchioles: Smaller, branching tubes that lead to the alveoli.
  7. Alveoli: Tiny, grape-like air sacs at the end of the bronchioles.
    • Function: The site of Gas Exchange. Oxygen moves from the alveoli into the blood capillaries via Diffusion (movement from high concentration to low concentration).
    • Surfactant: A substance that coats the alveoli to keep them from collapsing.

B. Muscles of Respiration

Breathing is a mechanical process driven by pressure changes.

  • Diaphragm: The large, dome-shaped muscle separating the thoracic and abdominal cavities.
    • Inhalation: The diaphragm contracts and moves down/flat, creating a vacuum that pulls air in.
    • Exhalation: The diaphragm relaxes and moves up, pushing air out.
    • Nerve Supply: The Phrenic Nerve controls the diaphragm. (Mnemonic: "C3, 4, 5 keeps the diaphragm alive").
  • Intercostal Muscles: Muscles between the ribs that help expand the chest wall.

2. Assessment: Signs, Symptoms, and Sounds

To assist the provider, you must be familiar with the terminology describing breathing patterns and sounds.

A. Medical Terminology for Breathing

Term Definition Clinical Context
Dyspnea Difficult, painful, or labored breathing. The patient says, "I can't catch my breath."
Apnea Temporary cessation (stopping) of breathing. Seen in Sleep Apnea.
Tachypnea Rapid breathing (usually > 20 breaths/min). Common in fever, anxiety, or hypoxia.
Bradypnea Slow breathing (usually < 12 breaths/min). Seen in drug overdose (opioids).
Orthopnea Difficulty breathing when lying flat. Patient must sleep propped up on pillows (common in Congestive Heart Failure).
Hypoxemia Low oxygen levels in the blood. SpO2 reading below 95%.
Cyanosis Bluish discoloration of the skin/lips. A late sign of severe hypoxia.
Hemoptysis Coughing up blood. Seen in Tuberculosis or lung cancer.
Epistaxis A nosebleed. Common injury or due to dry air/hypertension.

B. Abnormal Breath Sounds (Auscultation)

You will often document these findings after the provider examines the patient.

Sound Description Associated Condition Memory Aid
Wheezing High-pitched whistling sound, usually on expiration. Asthma, COPD. Indicates narrowed airways. A whistle is a wheeze.
Rales (Crackles) Clicking, rattling, or bubbling sounds. Pneumonia, Heart Failure. Indicates fluid in the alveoli. Rales in the tails (fluid in the deep lungs).
Stridor High-pitched, crowing sound on inspiration. Croup, Foreign Body Obstruction. Indicates an Upper Airway blockage. Stridor is a struggle (emergency).
Rhonchi Low-pitched, snoring, or rattling sound. Bronchitis. Indicates mucus in the large airways. Rhonchi sounds like a Rhino snoring.

3. Common Diseases and Pathophysiology

For the CCMA exam, focus on the pathophysiology (what is going wrong), the symptoms, and the treatments MAs assist with.

1. Chronic Obstructive Pulmonary Disease (COPD)

  • Definition: A progressive, irreversible lung disease that blocks airflow and makes it difficult to breathe. It is an umbrella term that includes Emphysema and Chronic Bronchitis.
  • Pathophysiology:
    • Emphysema: The alveoli are destroyed, losing elasticity. Air gets trapped in the lungs.
    • Chronic Bronchitis: Inflammation of the lining of the bronchial tubes, causing excess mucus.
  • Risk Factors: Smoking is the #1 cause. Occupational exposure to dust/chemicals.
  • Signs & Symptoms: Chronic cough, dyspnea, wheezing, fatigue.
    • Barrel Chest: Patients with emphysema often develop a rounded, bulging chest because their lungs are chronically over-inflated.
  • Treatment: Bronchodilators, inhaled steroids, smoking cessation, supplemental oxygen.

Exam Tip: If a question mentions "Barrel Chest" or "Clubbing of the fingers" (fingertips look round/bulbous), think COPD/Emphysema and Hypoxia.

2. Asthma

  • Definition: A chronic inflammatory disorder causing reversible obstruction of the airways.
  • Pathophysiology: The airways narrow due to three factors: swelling (inflammation), tightening of muscles around airways (bronchospasm), and excess mucus.
  • Triggers: Allergens (pollen, pets), exercise, cold air, stress.
  • Signs & Symptoms: Wheezing, coughing (worse at night/early morning), chest tightness, shortness of breath.
  • Diagnostic Test: Spirometry (measuring airflow) before and after using a bronchodilator.
  • Treatment:
    • Rescue Inhalers: Rapid-acting bronchodilators (e.g., Albuterol) for acute attacks.
    • Maintenance: Inhaled corticosteroids to prevent attacks.

3. Pneumonia

  • Definition: An infection that inflames the air sacs in one or both lungs.
  • Pathophysiology: The alveoli fill with fluid or pus (purulent material), preventing gas exchange.
  • Causes:
    • Bacterial: Streptococcus pneumoniae (most common).
    • Viral: Influenza, RSV.
    • Fungal: In immunocompromised patients.
    • Aspiration: Inhaling food/vomit into the lungs.
  • Signs & Symptoms: High fever, chills, cough with phlegm (green/yellow/bloody), chest pain when breathing, Rales/Crackles on auscultation.
  • Treatment: Antibiotics (if bacterial), fluids, rest, antipyretics (fever reducers).

4. Pulmonary Embolism (PE)

  • Definition: A blockage in one of the pulmonary arteries in the lungs.
  • Pathophysiology: Usually caused by a blood clot (Deep Vein Thrombosis - DVT) that travels from the legs to the lungs.
  • Risk Factors: Immobility (long flights, bed rest), surgery, birth control pills, smoking.
  • Signs & Symptoms: Sudden onset shortness of breath, sharp chest pain (worse when inhaling), rapid heart rate, coughing up blood.
  • Urgency: This is a medical emergency. MAs must recognize the signs and alert the provider immediately.
  • Diagnosis: D-dimer blood test, CT Angiography.

5. Influenza (The Flu)

  • Definition: A highly contagious viral infection of the respiratory system.
  • Signs & Symptoms: Sudden onset of fever, muscle aches (myalgia), chills, fatigue, dry cough.
  • Prevention: Annual vaccination (Artificial Active Immunity).
  • Pediatric Warning: Never give Aspirin to a child or teen with viral flu symptoms. It is linked to Reye's Syndrome (liver/brain damage).

6. Tuberculosis (TB)

  • Definition: A potentially serious infectious bacterial disease that mainly affects the lungs.
  • Pathogen: Mycobacterium tuberculosis.
  • Signs & Symptoms: Cough lasting >3 weeks, hemoptysis (coughing up blood), night sweats, fever, unintentional weight loss.
  • Transmission: Airborne. The bacteria can hang in the air for hours.
    • MA Safety: Patients suspected of having active TB must be placed in isolation (negative pressure room), and staff must wear N95 respirators.
  • Diagnosis:
    • PPD Skin Test (Mantoux): Screening test.
    • Chest X-Ray & Sputum Culture: Confirms active disease.

7. Cystic Fibrosis (CF)

  • Definition: A life-threatening genetic disorder that damages the lungs and digestive system.
  • Pathophysiology: A defective gene causes the body to produce unusually thick, sticky mucus. This mucus clogs the lungs (leading to infections) and obstructs the pancreas (preventing enzyme release).
  • Signs & Symptoms: Persistent cough with thick mucus, frequent lung infections, poor growth/weight gain, salty-tasting skin.
  • Diagnosis: Sweat Chloride Test (measures salt in sweat).
  • Treatment: Chest physical therapy (percussion) to loosen mucus, digestive enzyme supplements, bronchodilators.

4. Diagnostic Procedures and MA Responsibilities

Pulmonary Function Testing (Spirometry)

A non-invasive test that measures how well the lungs work.

  • Purpose: Diagnoses asthma and COPD. Measures lung volume and airflow speed.
  • Key Metrics:
    • FVC (Forced Vital Capacity): The total amount of air exhaled during the FEV test.
    • FEV1: Forced Expiratory Volume in 1 second.
  • MA Role (Patient Coaching): The validity of the test depends on patient effort. You must coach them to:
    1. Take the deepest breath possible.
    2. Seal lips tightly around the mouthpiece.
    3. Blow out as hard and fast as possible until the lungs are completely empty (usually 6 seconds).
    4. Repeat until 3 acceptable efforts are recorded.

Pulse Oximetry

Measures the oxygen saturation of the blood (SpO2).

  • Normal Range: 95% - 100%.
  • Hypoxemia: Below 95% (concern varies by patient/condition; COPD patients may live at 90-92%).
  • Troubleshooting: Readings can be inaccurate due to:
    • Cold hands (poor circulation).
    • Dark nail polish or artificial nails (blocks the light sensor).
    • Movement.

Sputum Culture

Used to identify the bacteria causing pneumonia or TB.

  • Collection Tip: The best time to collect a sputum specimen is early morning, before the patient eats or drinks. The secretions have pooled in the lungs overnight, providing the most concentrated sample.

Mantoux Tuberculin Skin Test (PPD)

Screening for TB exposure.

  • Administration: Intradermal injection (10-15 degree angle) on the forearm to create a "wheal."
  • Reading: The patient must return in 48 to 72 hours.
  • Interpretation: You measure the Induration (the hard, raised bump), NOT the redness.

5. Final Key Takeaways

  • Structure: Gas exchange happens in the Alveoli via diffusion.
  • Sounds: Wheezing = Asthma/narrow airways. Rales/Crackles = Pneumonia/fluid. Stridor = Blockage (Emergency).
  • Emergencies: Pulmonary Embolism presents with sudden shortness of breath and chest pain; risk factors include DVT and immobility.
  • Safety: Active TB requires Airborne Precautions and an N95 mask.
  • Pathology:
    • COPD: Linked to smoking; includes Emphysema (barrel chest) and Bronchitis.
    • Cystic Fibrosis: Genetic; thick mucus + salty skin.
    • TB: Night sweats + coughing up blood.
  • Procedures:
    • Spirometry: Coaching is critical; patient blows hard and fast.
    • PPD: Read in 48-72 hours; measure the bump (induration), not the red area.
    • Flu: No Aspirin for children (Reye's Syndrome).