LECTURE 7: • Know all the components of the respiratory system and their major functions We need to transfer O2 from the atmosphere to our tissues and CO2 from the tissues into the atmosphere. Respiratory system also: • Assists pH homeostasis • Produces vocal sounds • Filters air and provides for a sense of smell • Assists regulation of heat and water The upper respiratory system includes: • Pharynx • Nose The lower respiratory system includes: • Larynx • Trachea • Right main bronchus • Lungs Principal organs of the respiratory system: • Nose- produces mucus, filters, warms and moistens incoming air • Paranasal sinuses- same as nose. Mucosa-lined, air filled cavities. • Pharynx- passage for air and food. Connects nasal cavity to larynx and oral cavity to esophagus. Has 3 subdivisions: nasopharynx, oropharynx, and laryngopharynx. The nasopharynx helps warm and humidify and filter the air. • Larynx- air passageway; prevents food from entering lower respiratory tract. It protects the glottis (large cartilages) and produces sound (small cartilage structures and vocal folds). There are 3 large cartilages: thyroid, cricoid cartilage and epiglottis. • Trachea- air passageway; cleans, warms and moistens incoming air • Bronchial tree- air passageway connecting trachea with alveoli; cleans, warms and moistens incoming air. The bronchi contain incomplete rings of cartilage and are lined by pseudostratified ciliated columnar epithelium. Consists of right and left main bronchi, which subdivide within the lungs to form lobar and segmental bronchi and bronchioles. Plates of cartilage gradually replace the incomplete rings of cartilage from main bronchi and finally disappear in the distal bronchioles. As the amount of cartilage decreases, the amount of smooth muscle increases. • Alveoli- main sites for gas exchange. Comprised of walls of simple squamous epithelium. • Lungs- house respiratory passages smaller than the main bronchi. Composed primarily of alveoli and respiratory passageways. Stroma is fibrous elastic