Histology of the Respiratory System - Lecture 1

A set of vocabulary flashcards detailing the histological structures, cell types, mucosa, and key anatomical components of the human respiratory system based on lecture notes.

Conducting portion

The structural division of the respiratory system comprising the nasal cavities, nasopharynx, larynx, trachea, bronchi, bronchioles, and terminal bronchioles that cleans, warms, and humidifies air.

Respiratory portion

The region of the respiratory system where gas exchange occurs, consisting of respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli.

Respiratory mucosa

The mucosal lining covering most conducting airways, composed of pseudostratified columnar epithelium and a highly vascular lamina propria firmly attached to underlying bone or cartilage.

Respiratory epithelium

A ciliated pseudostratified columnar epithelium lining most of the conducting system, containing five major cell types resting on a thick basement membrane.

Ciliated columnar cells

The most abundant cell type in the respiratory epithelium, each possessing approximately $300$ cilia on its apical surface to propel the mucous blanket toward the pharynx.

Immotile cilia syndrome

A disorder causing male infertility and chronic respiratory tract infections in both sexes, resulting from ciliary and flagellar immobility often caused by a deficiency of dynein.

Goblet cells

Abundant respiratory epithelial cells filled at their apical regions with granules of mucin glycoproteins, which exhibit increased secretion during infection or irritation.

Brush cells

Columnar chemosensory receptor cells in the respiratory epithelium that feature a small apical tuft of microvilli and form synaptic contact with afferent nerve endings on their basal surfaces.

Small granule cells

Cells of the diffuse neuroendocrine system that represent about $3\%$ of total respiratory epithelial cells and contain numerous dense granules.

Basal cells

Small, rounded stem cells located on the basement membrane that do not extend to the luminal surface and serve to give rise to other epithelial cell types.

Vibrissae

Coarse, moist hairs located in the dilated nasal vestibule that function to filter out particulate matter from inspired air.

Olfactory glands (of Bowman)

Large serous glands located in the lamina propria of the olfactory mucosa that produce a continuous flow of fluid to submerge olfactory cilia and clear odorants.

Olfactory neurons

Bipolar sensory neurons in the olfactory epithelium whose dendrites feature non-motile cilia with chemoreceptors, and whose axons pass through the cribriform plate of the ethmoid bone to form cranial nerve I.

Paranasal sinuses

Bilateral air-filled cavities in the frontal, maxillary, ethmoid, and sphenoid bones lined with thin respiratory epithelium that lighten the skull and provide vocal resonance.

Sinusitis

An inflammatory condition of the paranasal sinuses that may persist for long periods primarily due to the obstruction of drainage orifices.

Epiglottis

A flattened structure reinforced by elastic cartilage projecting from the upper rim of the larynx that prevents swallowed food or fluid from entering the airway.

Vestibular folds

The upper, immovable pair of mucosal folds in the larynx covered with typical respiratory epithelium overlying seromucous glands and lymphoid nodules.

Vocal folds

The lower pair of laryngeal folds responsible for sound production, lined by non-keratinized stratified squamous epithelium and containing the vocal ligament and vocalis muscle.

Trachealis muscle

A band of smooth muscle bridging the posterior open ends of the C-shaped hyaline cartilage rings in the trachea, which relaxes during swallowing and contracts during the cough reflex.

Tracheal wall layers

The four histological layers of the trachea consisting of mucosa (epithelium and lamina propria), submucosa (with seromucous glands), cartilaginous layer (hyaline cartilage rings), and adventitia.