chapter 25 A

Respiratory System: Upper and Lower Tracts (through Trachea)

• The respiratory system is anatomically divided into upper and lower respiratory tracts.
• It is functionally divided into conducting and respiratory portions.
• The upper respiratory tract includes the nose, nasal cavities, paranasal sinuses, and pharynx.
• The lower respiratory tract includes the larynx, trachea, bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, and alveoli. These structures are involved in gas exchange.
• The trachea is anterior to the esophagus and inferior to the larynx, it is also superior to the main bronchi. It has C-shaped cartilaginous rings that support its structure.
• The larynx is commonly called the voice box.
  • It connects the pharynx to the trachea.
  • The epiglottis is a spoon-shaped cartilage that projects superiorly into the pharynx. It plays a role in swallowing, closing the larynx opening during this process.
  • The larynx's functions include being a passageway for air, preventing ingested materials from entering the respiratory tract, producing sound for speech, and participating in sneeze and cough reflexes.
  • The thyroid cartilage is the largest cartilage in the larynx, also known as the Adam's apple.
  • The cricoid cartilage is another important cartilage in the larynx.
  • The rima glottidis is the glottis opening, air passing through this opening causes the vocal cords to vibrate and create sound that is then modified into speech.
• The functions of the respiratory system include pulmonary ventilation (breathing), gas exchange (between the atmosphere and blood), conditioning inspired air (warming, humidifying, cleaning), sound production, and defense against pathogens.
• The pharynx is a shared passageway for both respiratory and digestive systems. It is divided into three regions: nasopharynx, oropharynx, and laryngopharynx.
• The nasopharynx is posterior to the nasal cavity and superior to the soft palate. It contains openings for the auditory tubes. The posterior nasopharynx contains the pharyngeal tonsils (adenoids).
• The oropharynx is bounded superiorly by the soft palate and inferiorly by the hyoid bone. This region is a shared passageway for both respiratory and digestive systems, contains the palatine tonsils, and the lingual tonsils.
• The laryngopharynx is inferior to the hyoid bone. It is also a shared passageway for respiratory and digestive systems.

Respiratory System Functions

• Pulmonary ventilation: Inhalation (inspiration) and exhalation (expiration)
• Gas exchange: Between atmosphere and blood
• Gas conditioning: Warming, humidifying, and cleaning inspired air.
• Sound production: Primarily from vibration of the vocal folds in the larynx.
• Olfaction: Smell
• Defense: Protection against airborne pathogens

Learning Outcomes

• Describe the major functions of the respiratory system
• Discuss locations and functions of the conducting and respiratory portions.
• Identify the structures of both upper and lower respiratory tracts, and vocal folds.
• Describe functions and features of nasal cavity, paranasal sinuses, and pharynx.
• Explain the major functions of the larynx, including laryngeal cartilages and vocal cords.
• Explain how vocal range, pitch, and loudness are determined.
• Explain the gross anatomical features, positioning, and significance of the trachea's C-shaped cartilages.