Human Respiratory System

Study Notes

Nasopharynx is the posterior continuation of nasal cavities and becomes continuous with the oropharynx at the level of the soft palate.
Larynx connects the pharynx with the trachea.
The wall of the larynx is supported by hyaline cartilage and striated muscle (skeletal muscle).
Vocal cords consist of skeletal muscle (vocalis muscle).
Anterior glottis is covered with Stratified squamous epithelium, posterior glottis is covered with pseudostratified ciliated epithelium.

Epiglottis closes off the trachea to prevent inhalation of solids or liquids.
Epiglottis is made of elastic cartilage.
Trachea has mucosa with pseudostratified ciliated columnar epithelium with goblet cells.
Submucosa is a connective tissue layer with many seromucous glands.
Hyaline cartilage is present in the trachea.
Adventitia contains dense connective tissue.

Bronchus has a short lumen, lined with pseudostratified ciliated columnar epithelium.
Bronchiole has a long lumen, lined with ciliated columnar cells, Clara cells, and present mucoserous glands.

Pneumocyte type I represents 97% of alveolar wall cells, has a cuboidal shape, and forms part of the blood-gas barrier.
Pneumocyte type II represents 3% of alveolar wall cells, has a rounded shape, and secretes surfactant to decrease surface tension of alveoli.

Hyaline membrane disease occurs in those who lack adequate amounts of pulmonary surfactant, causing labored breathing.
Asthma is a constriction of smooth muscle in bronchioles, causing decreased diameter and dyspnea.
Emphysema is the destruction of alveolar walls and formation of large cyst-like sacs, reducing surface area available for gas exchange.