Anatomy of the Respiratory System

Study Notes

Upper Respiratory System

Nose: External opening; divided into two cavities (nostrils) by the nasal septum, containing hair follicles, sweat, and sebaceous glands that filter air.
Sinuses: Located in frontal, ethmoid, sphenoid, and maxillary bones; lighten skull, assist in speech, and produce mucus for debris trapping.
Pharynx: Funnel-shaped tube about 5 inches (13 cm) long; serves both air and food passage.
Larynx: Approximately 2 inches (5 cm) long; channels air and food into the appropriate pathways.
Trachea: Ranges from 4-5 inches (12-15 cm) long and 1 inch in diameter; comprises 16-20 C-shaped cartilage rings connected by tissue.
Respiratory Passages: Include nasal cavity, pharynx, larynx, trachea, and bronchi; facilitate air movement into lungs and food transfer to the esophagus.

Lower Respiratory System

Lungs: Comprised of elastic connective tissue (stroma); left lung has 2 lobes, right lung has 3. Pulmonary arteries bring deoxygenated blood to lungs; pulmonary veins carry oxygenated blood to the heart.
Pleura: Double-layered membrane enveloping lungs and thoracic cavity; produces pleural fluid to reduce friction during breathing.
Bronchi: Divide into right/left primary bronchi, secondary (lobar), tertiary (segmental) bronchi, and bronchioles, collectively forming the bronchial tree. The right primary bronchus is shorter and wider.
Alveoli: Functional units of lungs; ~300 million in adults where gas exchange occurs, clustered around alveolar sacs.

Factors Affecting Ventilation and Respiration

Changes in Respiratory Volume and Capacity:
- Tidal Volume (TV): Amount of air (approx. 500 mL) inhaled/exhaled in normal breath.
- Inspiratory Reserve Volume (IRV): Additional air (2100-3100 mL) that can be forcibly inhaled.
- Expiratory Reserve Volume (ERV): Air (approx. 1000 mL) that can be forcibly exhaled.
- Residual Volume (RV): Air (approx. 1100 mL) remaining in lungs post-expiration.
- Vital Capacity (VC): Total exhaled air post-maximal inhalation, calculated from IRV, TV, and ERV (approx. 4500 mL).
- Anatomic dead space volume is about 150 mL of air that doesn't reach alveoli.
Gas Concentrations: Respiratory centers and chemoreceptors react to levels of O2, CO2, and hydrogen ions.
Airway Resistance and Lung Compliance:
- Resistance from friction in airway passageways, constriction, mucus accumulation, or tumors.
- Lung compliance indicates the lungs' stretchability, influenced by lung elasticity and rib cage flexibility.
Alveolar Surface Tension: Molecules at gas-liquid boundaries are more attracted to each other, creating surface tension. Surfactant reduces this tension, aiding lung expansion.
Air Pressures:
- Intrapulmonary Pressure: Fluctuates within alveoli during ventilation.
- Intrapleural Pressure: Lower than intrapulmonary pressure; also varies with ventilation.
- During inspiration, lung expansion lowers intrapulmonary pressure, causing air to flow in.

Description

This quiz explores the anatomy, physiology, and functions of the respiratory system, with a focus on the upper respiratory system. Questions cover the structure and function of the nose and sinuses, including their roles in air filtration and mucus production.