Gross and Microscopic Anatomy of the Respiratory System

Comprehensive vocabulary flashcards covering the gross, regional, and microscopic anatomy of the human respiratory system and comparative sheep lung specimens.

Hard Palate

The bony floor of the nasal cavity composed anteriorly of the palatine process of the maxilla and posteriorly of the horizontal plate of the palatine bone.

Nasal Conchae

Three pairs of scroll-like bony projections on the lateral walls of the nasal cavity—superior and middle (ethmoid bone) and inferior (separate bones)—that swirl incoming air to filter, humidify, and warm it.

Nasal Meatuses

Grooves or narrow tunnels located beneath each corresponding nasal concha (superior, middle, and inferior meatuses).

Paranasal Sinuses

Air-filled, mucus-producing cavities within skull bones—specifically the frontal, sphenoid, ethmoid, and maxillary sinuses—that drain into the nasal cavity to warm, moisten, and filter air.

Nasal Vestibule

The dilated anterior portion and entrance of the nasal cavity located immediately internal to each naris (nostril).

Olfactory Region

The superior area of the nasal cavity containing olfactory nerve fibers that pass through the cribriform plate of the ethmoid bone to reach the olfactory bulb for the sense of smell.

Posterior Nasal Apertures (Choanae)

The paired bony openings at the posterior margin of the nasal cavity that lead directly into the nasopharynx.

Nasopharynx

The uppermost division of the pharynx, extending from the posterior nasal apertures to the soft palate, serving exclusively as an airway.

Pharyngeal Tonsil

A lymphoid mass located in the posterior wall of the nasopharynx that traps inhaled airborne pathogens.

Auditory Tube (Eustachian Tube)

A channel linking the nasopharynx to the middle ear cavity that equalizes atmospheric air pressure on both sides of the tympanic membrane.

Uvula

The conical, finger-like inferior projection hanging from the free posterior margin of the soft palate.

Nasal Septum

The midline partition separating the nasal cavity into right and left halves, formed anteriorly by septal cartilage (hyaline cartilage), superiorly by the perpendicular plate of the ethmoid bone, and inferiorly by the vomer.

Oropharynx

The middle subdivision of the pharynx, stretching between the tip of the uvula and the base of the hyoid bone / tip of the epiglottis, housing the palatine and lingual tonsils.

Laryngopharynx

The most inferior segment of the pharynx, located below the oropharynx adjacent to the upright epiglottis and leading to the esophagus and larynx.

Epiglottis

A spoon-shaped flap of elastic cartilage attached to the larynx that folds downward to seal the laryngeal inlet during swallowing.

Thyroid Cartilage

The largest laryngeal cartilage; a shield-shaped hyaline cartilage structure that protects the anterior and lateral larynx and forms the laryngeal prominence.

Laryngeal Prominence

The anterior midline protrusion formed by the fusion of the thyroid cartilage plates, commonly called the Adam's apple.

Cricoid Cartilage

A complete, ring-shaped ring of hyaline cartilage located inferior to the thyroid cartilage that marks the inferior boundary of the larynx.

Vocal Folds (True Vocal Cords)

The inferior pair of laryngeal mucosal folds that vibrate as air flows past them to produce sound.

Vestibular Folds (False Vocal Cords)

The superior pair of mucosal folds in the larynx that do not produce sound, but function to close the larynx and protect the true vocal cords during swallowing.

Glottis

The slit-like opening and space situated directly between the right and left true vocal folds.

Trachea

The primary windpipe connecting the larynx to the main bronchi, kept patent by C-shaped hyaline cartilage rings.

Trachealis Muscle

Smooth muscle located on the posterior wall of the trachea spanning the open gap of the C-shaped cartilage rings, allowing expansion of the adjacent esophagus during swallowing.

Diaphragm

The primary dome-shaped muscle of inspiration separating the thoracic and abdominal cavities; it contracts and descends to enlarge thoracic volume during inhalation.

Right Lung

The lung divided into $3$ lobes (superior, middle, inferior) separated by the horizontal fissure and the oblique fissure.

Left Lung

The lung divided into $2$ lobes (superior, inferior) by an oblique fissure, featuring an indentation called the cardiac notch.

Cardiac Notch

A distinct medial concavity on the anterior border of the left lung that accommodates the apex of the heart.

Horizontal Fissure

The fissure found exclusively on the right lung separating the superior lobe from the middle lobe.

Oblique Fissure

The anatomical groove found on both lungs; it separates the middle and inferior lobes on the right lung, and the superior and inferior lobes on the left lung.

Main Bronchi

The right and left primary airway tubes formed by the bifurcation of the trachea in the mediastinum.

Lobar Bronchi

Secondary branches of the bronchial tree that deliver air to individual lung lobes ($3$ in the right lung and $2$ in the left lung).

Segmental Bronchi

Tertiary airway branches originating from lobar bronchi that supply individual bronchopulmonary segments and contain irregular hyaline cartilage plates.

Terminal Bronchiole

The final conducting airway segment that lacks cartilage and represents the last structure devoid of alveoli.

Pulmonary Lobule

The functional and anatomical unit of the lung, consisting of a terminal bronchiole, respiratory branches, alveolar ducts, alveolar sacs, capillaries, and elastic fibers surrounded by connective tissue.

Alveolar Duct

An elongated airway tube lined with elastic fibers and opening outward into multiple alveoli.

Alveolar Sac

A terminal, grape-like cluster composed of two or more contiguous alveoli sharing a common opening.

Alveolus

A microscopic, cup-shaped sac lined by simple squamous epithelium surrounded by elastic fibers and capillaries, serving as the main site of gas exchange.

Respiratory Membrane

The composite diffusion barrier consisting of the alveolar simple squamous epithelium, its basement membrane, the capillary basement membrane, and the capillary endothelium.

Visceral Pleura

The delicate serous membrane firmly attached to and covering the outer surface of each lung and dipping into its fissures.

Parietal Pleura

The outer serous membrane layer that lines the inner surface of the thoracic wall, superior diaphragm, and mediastinum.

Pleural Cavity

The potential space between the visceral and parietal pleurae filled with serous pleural fluid to minimize friction during ventilation.

Costal Surface

The smooth, convex surface of the lung that lies directly against the inner contours of the ribs and intercostal muscles.

Mediastinal Surface

The medial aspect of each lung that faces toward the mediastinum and contains the lung root / hilum.

Accessory Lobe

An additional, fourth anatomical lobe present in the right lung of quadruped mammals such as sheep, absent in human lungs.

Dorsal Groove

The longitudinal depression situated between the lungs on the dorsal view of a sheep lung where the descending thoracic aorta, azygos vein, and esophagus run.

Pseudostratified Ciliated Columnar Epithelium

The single-layered respiratory mucosal lining containing columnar cells of varying heights whose differing nuclear levels mimic stratification, equipped with apical cilia to propel mucus toward the pharynx.

Goblet Cells

Unicellular, mucus-secreting epithelial cells interspersed throughout the pseudostratified ciliated columnar lining of the conducting airways.

Seromucous Glands

Exocrine glands embedded in the tracheal submucosa that secrete a watery and mucus mixture into the lumen to trap foreign debris.

Tracheal Adventitia

The outermost fibrous connective tissue layer of the trachea that anchors it to adjacent structures such as the esophagus.