Untitled Quiz

Respiratory System Organs

• The respiratory system includes the nose, nasal cavity, paranasal sinuses, pharynx, larynx, trachea, bronchi, and lungs, which contain terminal air sacs or alveoli.

Alveoli

• Alveoli are microscopic chambers at the end of the bronchial tree, walled by simple squamous epithelium, where gas exchange occurs.
• Type II alveolar cells produce surfactant, reducing surface tension and preventing lung collapse.

Bronchial Tree

• The bronchial tree consists of right and left main bronchi, which subdivide into lobar, segmental, and smaller bronchi, and bronchioles.
• Bronchiolar walls contain smooth muscle, which, when constricted, impedes expiration.

Trachea

• The trachea is a flexible tube running from the larynx, dividing into two main bronchi.
• Its walls contain C-shaped cartilages, incomplete posteriorly, with trachealis muscle.
• Functions include air passage, warming, and moistening incoming air.

Larynx

• The larynx connects the pharynx to the trachea.
• It houses the vocal cords.

Pharynx

• The pharynx connects the nasal cavity to the larynx and the oral cavity to the esophagus.
• It is divided into nasopharynx, oropharynx, and laryngopharynx.
• The pharynx is a passageway for air and food and houses tonsils, which respond to inhaled or ingested antigens.

Paranasal Sinuses

• Paranasal sinuses are mucosa-lined hollow cavities within sphenoid, ethmoid, maxillary, and frontal bones.
• They function the same as the nasal cavity and lighten the skull.

Nose

• The nose is the external portion of the respiratory system, supported by bone and cartilage.
• The internal nasal cavity is divided by the midline nasal septum and lined with respiratory mucosa.
• The nose produces mucus, filters, warms, and moistens incoming air, and serves as a resonance chamber for speech.
• The roof of the nasal cavity contains olfactory mucosa (receptors for the sense of smell).

Conducting and Respiratory Zones

• The conducting zone includes respiratory passageways that carry air to the sites of gas exchange.
• The respiratory zone is the actual site of gas exchange in the lungs, composed of the terminal respiratory passageways that contain alveoli, namely respiratory bronchioles, alveolar ducts, and alveolar sacs.