Respiratory Physiology Quiz

Introduction to the Respiratory System

• The respiratory system's purpose is to exchange gases (oxygen & carbon dioxide) between the body and the environment.
• It consists of both upper and lower airways; the upper airway filters, warms, and humidifies air, moving it toward the lower airway.
• The lower airway transports air to the lungs, where gas exchange takes place in the alveoli.

Chapter Objectives

• Describe normal structures and functions of the respiratory system.
• Identify how aging affects the respiratory system.
• List data to collect when caring for a patient with a respiratory disorder.
• Recognize findings during inspection, palpation, percussion, and auscultation of the chest.
• Identify common diagnostic tests for respiratory disorders.
• Plan nursing care for patients undergoing diagnostic tests.
• Discuss therapeutic measures used to help patients with respiratory disorders.

Normal Respiratory Anatomy

• Upper Airway: Nose, sinuses, turbinates, pharynx, larynx
• Lower Airway: Trachea, bronchi, bronchioles, lungs, alveoli

Nose and Nasal Cavities

• Nares are the external openings of the nose.
• The nasal septum divides the internal nose into two cavities.
• The nasal cavities have a vascular and ciliated mucous lining that warms and humidifies air.
• Olfactory sensory cells in the nasal mucosa detect smells.
• Turbinate bones (conchae) change the flow of inspired air, warming and moisturizing it, and trapping dust and microorganisms.

Paranasal Sinuses

• Frontal sinuses are located in the frontal bone above the eye sockets.
• Ethmoid sinuses are small, honeycomb-like spaces between the eyes, in the ethmoid bone.
• Sphenoid sinuses lie behind the nasal cavity in the sphenoid bone.
• Maxillary sinuses are the largest and most accessible sinuses located in the cheekbones, on either side of the nose.

Pharynx (Throat)

• Carries air to the larynx and food to the esophagus.
• Divided into three areas: nasopharynx, oropharynx, and laryngeal pharynx.
• Nasopharynx is near the nose and above the soft palate, contains adenoids (pharyngeal tonsils) and openings of the eustachian tubes.
• Oropharynx is near the mouth and contains the tongue and palatine tonsils (they help prevent infection).
• Laryngeal pharynx is near the larynx.

Larynx (Voice Box)

• Cartilaginous framework between the pharynx and trachea.
• Primary function is producing sound.
• Protects the lower airway from foreign objects (coughing).
• The pharynx, palate, tongue, teeth, and lips shape the sounds made by the vocal cords into speech.
• Important structures include the epiglottis (cartilaginous valve covering the larynx during swallowing), the glottis (opening between the vocal cords), vocal cords (vibrating to produce sound), cricoid cartilage (only complete cartilaginous ring in the larynx), and the thyroid cartilage (forms the Adam's apple).

Trachea (Windpipe)

• Hollow tube made of smooth muscle and C-shaped cartilage.
• Cartilage is incomplete on the posterior surface.
• Transports air from the laryngeal pharynx to the bronchi and lungs.
• Bifurcates (divides) at the carina into the right and left bronchi.
• The carina triggers coughing and bronchospasm to prevent foreign object aspiration.

Bronchi and Bronchioles

• Right main stem bronchus is shorter, more vertical, and larger than the left.
• Foreign objects more likely to be aspirated into the right side.
• Bronchi branch into smaller bronchi and then into terminal bronchioles.

Lungs and Alveoli

• Paired elastic structures in the thoracic cavity.
• Alveoli are small, clustered sacs that begin where bronchioles end.
• Three alveolar cell types: Type I (95% surface area), Type II (5% surface area producing surfactant that reduces surface tension), Type III (alveolar macrophages that ingest foreign matter).
• Approximately 300 million alveoli in adult lungs.
• The capillaries surrounding alveoli facilitate oxygen and carbon dioxide exchange.

Alveoli Details

• Alveolus is a thin membrane-lined sac.
• Gas exchange occurs across the thin alveolar and capillary walls.
• Alveoli are numerous (millions), thus creating a huge surface area for gas exchange.

Pulmonary Capillaries

• Pulmonary capillaries provide deoxygenated blood, and oxygenated blood to/from the alveoli.
• This structure is crucial for efficiently oxygenating and deoxygenating the blood

Accessory Structures

• Diaphragm: Separates the abdominal and thoracic cavities. Inspiration involves respiratory muscle contraction (the diaphragm flattens out), enlarging the chest and creating a partial vacuum to draw air in. During exhalation, respiratory muscles relax and the diaphragm returns to its original position.
• Mediastinum: Wall dividing the thoracic cavity into two halves, composed of the visceral and parietal pleura. Visceral pleura covers the lung surface, the parietal pleura covers the chest wall.

Did You Know

• Airway patency is constantly maintained, even during sleep.
• The esophagus collapses when not carrying food.

The Mechanism of Ventilation

• Inhalation is more effort-intensive than exhalation because respiratory muscles contract during inhalation.
• Rib cage moves up and out during inhalation, diaphragm flattens.
• The opposite occurs during exhalation.

Lung Volumes

• Vital Capacity (VC): Maximum amount of air exchanged during a full breath.
• Typically, VC is between 3400-3800 ml in males and 3800 ml in females.

Lung Volumes: Tidal Volume

• Normal breathing usually only uses a fraction of vital capacity. The tidal volume (TV) takes the normal respiratory cycle into account during inhalation and exhalation

Lung Volumes: Inspiratory & Expiratory Reserve Volumes

• Inspiratory reserve volume (IRV) is the max volume of air that can be inhaled after a normal inspiration.
• Expiratory reserve volume (ERV) is the max volume that can be exhaled after a normal expiration.

Diffusion

• Diffusion is the transfer of oxygen or carbon dioxide across a capillary or alveolar capillary membrane or between cells.
• High concentration of gas moves toward a low concentration; CO2 in cells moves into blood.
• CO2 diffuses from the blood into alveoli.

Gas Exchange: Capillaries and Alveoli

• Blood carries CO2 from body tissues to the lungs.
• CO2 diffuses from capillaries into alveoli.
• Blood in the pulmonary capillaries receives oxygen from alveoli.
• Oxygen diffuses from alveoli to pulmonary capillaries

Requirements for Gas Exchange

• Circulatory system is required to bring blood quickly to and from the lungs.
• Blood passing through the pulmonary capillaries efficiently carries oxygen or carbon dioxide to and from the alveoli.

Alveolar Respiration

• Alveolar respiration determines the level of CO2 in the body.
• The analysis of ABGs (arterial blood gases) determines the alveolar ventilation.

Perfusion

• Blood supply to the lungs; nutrients and oxygen supplied through bronchial and pulmonary circulation.
• Bronchial circulation supports the structures of the respiratory tract.
• Pulmonary circulation supplies blood to gas exchange.

Pulmonary Circulation

• Transport of venous blood into the lungs, the right and left sides of the lungs are supplied by this system.
• Blood circulates to and from the lungs through pulmonary capillaries.
• This is considered a low-pressure system.

Ventilation/Perfusion Ratio (V/Q Ratio)

• Measures the efficiency of airflow and gas exchange in the lungs.
• A low V/Q ratio indicates a shunt.
• A high V/Q ratio indicates dead space.
• A silent unit occurs when there is a lack of airflow and blood flow.

Oxygen Transport

• Oxygen loading and unloading of hemoglobin happens in two steps: pulmonary capillaries and peripheral tissues.

Respiration and Acid-Base Balance

• Compensation for imbalances by respiratory and/or renal systems, such as with acidosis and alkalosis.

Diagnostic Tests for the Respiratory System

• ABGs: measuring arterial blood gases (pH, O2, CO2, and HCO3) to evaluate respiratory function.
• Pulmonary function studies: assesses lung's functional capacity during inhalation and exhalation.
• Sputum studies: diagnosing infections or cancer by examining collected sputum samples.
• Imaging studies: chest X-rays, CT scans, or MRIs to view the lungs and surrounding structures.
• Pulmonary angiography: visualizing lung's blood vessels.
• Lung scans (VQ scan): examine blood and air flow in lungs.
• Gallium scan: Identifies inflammation, abscesses, adhesions, or tumors in lungs.
• Bronchoscopy: visualizes larynx, trachea, and bronchi; biopsies, treatments.
• Laryngoscopy: visualization and treatment of larynx.
• Mediastinoscopy: visualization of mediastinum from an incision above sternum.
• Thoracoscopy: examining pleural cavities; aspiration of fluid & tissue biopsies.
• Thoracentesis: aspiration of fluid or air from the pleural space.

Other Considerations

• Breathing exercises like diaphragmatic and pursed-lip breathing.
• Oxygen therapy (low-flow devices, masks, and high-flow devices).
• Chest drainage, tracheostomy; Mechanical and noninvasive ventilation (BiPap, CPAP).