Anatomy of the Airways & Alveoli Vocabulary

Flashcards covering key anatomical terms, structures, and physiological concepts from Beachey Chapter 1 on the upper/lower airways and alveoli.

Ventilation

The mechanical process of moving gas in and out of the lungs.

Respiration

The swapping of oxygen ($\text{O}_2$) and carbon dioxide ($\text{CO}_2$), categorized as external (lungs to blood) or internal (capillaries to tissues).

Conducting Airways

The anatomical deadspace pathway that connects outside air to the gas-exchange membrane without performing gas exchange, focusing on air transport, filtration, warming, and humidification.

Respiratory Zones

The functional gas-exchange units of the lung where external respiration occurs across a permeable barrier.

Nares

The external anterior openings to the nasal cavity.

Nasal Septum

A dividing structure in the nose composed of cartilage anteriorly and the vomer and ethmoid bones posteriorly, creating two nasal fossae.

Choanae

Posterior openings through which the two nasal fossae empty into the nasopharynx.

Turbinates (Conchae)

Three downward-sloping, scroll-shaped bones (superior, middle, inferior) on the lateral nasal wall that increase surface area, increase airflow resistance, and create air turbulence.

Intubation

The insertion of an artificial airway through the nose or mouth into the trachea, bypassing the upper airway's natural heating and humidifying mechanisms.

Pharynx

A muscular tube posterior to the nasal and oral cavities that serves as a shared passageway for air and food leading to the larynx and esophagus.

Nasopharynx

The portion of the pharynx located behind the nasal cavity, extending from the base of the skull to the soft palate.

Oropharynx

The portion of the pharynx located behind the oral cavity, extending from the soft palate to the hyoid bone at the base of the tongue.

Laryngopharynx

The portion of the pharynx located behind the larynx, extending from the hyoid bone to the cricoid cartilage.

Glossopharyngeal Nerve (9th Cranial Nerve)

The sensory nerve component responsible for initiating defensive reflexes in the pharyngeal musculature to prevent aspiration.

Vagus Nerve (10th Cranial Nerve)

The motor nerve component of the pharyngeal musculature that also mediates the laryngeal reflex causing laryngospasm.

Larynx

A cylindrical cartilaginous structure located at vertebrae level C4-C6 that acts as a protective valve atop the trachea, houses the vocal cords, and marks the boundary between the upper and lower airways.

Thyroid Cartilage

The largest cartilage component of the larynx.

Cricoid Cartilage

The only laryngeal structure forming a complete cartilaginous ring around the airway, representing the narrowest region of the upper airway in infants.

Epiglottis

A thin, leaf-shaped cartilage attached at its lower end to the thyroid cartilage that elevates and closes during swallowing to protect the airway.

Vallecula

A small anatomical pocket located between the base of the tongue and the epiglottis.

Glottis

The triangular opening between the true vocal folds leading into the trachea, constituting the narrowest part of the adult larynx.

Laryngospasm

A defensive laryngeal reflex mediated by the 10th cranial nerve that causes the vocal cords to close tightly over the tracheal opening when non-air stimuli contact the area.

Dichotomous Branching

A pattern of airway division in which each parent airway splits into two smaller daughter airways.

Isothermic Saturation Boundary (ISB)

The point in the airway below which inhaled gas achieves a constant temperature of 37^\bar{C} and $100\%$ relative humidity.

Parenchyma

The supportive tissue of the lung, containing elastic fibers attached to small airways that prevent airway collapse during forceful exhalation.

Bronchioles

Small conducting airways less than $1\,mm$ in diameter that lack cartilage in their walls and rely on parenchymal elastic tethering to stay open.

Acinus

The functional respiratory unit located beyond the terminal bronchioles, comprising respiratory bronchioles, alveolar ducts, and alveolar sacs.

Serous Cells

Epithelial cells in the airway that can transform into goblet cells when exposed to chronic pollutants such as cigarette smoke.

Kulchitsky Cells

Airway endocrine cells predominant in newborns that serve as precursors to carcinoids and small cell bronchogenic carcinomas.

Clara Cells

Non-ciliated secretory cells located in terminal and respiratory bronchioles that provide local mucus production.

Eosinophils

White blood cells that proliferate in response to allergic inflammation and are commonly elevated during allergic asthma exacerbations.

Neutrophils

White blood cells (pus cells) that migrate into the airways to engulf and phagocytize bacteria during active bacterial infections.

Mast Cells

Cells in the airway epithelium containing inflammatory mediators like histamine, prostaglandins, and leukotrienes that trigger mucosal swelling and bronchospasm.

Type I Cells (Type I Pneumocytes)

Flat squamous epithelial cells that form approximately $95\%$ of the alveolar wall structure.

Type II Cells (Type II Pneumocytes)

Cuboidal alveolar cells containing lamellar bodies that synthesize and secrete pulmonary surfactant.

Interstitium

The tissue space between the basement membranes of the alveolar epithelium and capillary endothelium that forms a blood-air barrier.

Pores of Kohn

Small openings that allow direct gas movement between adjacent alveoli.

Canals of Lambert

Microscopic channels connecting terminal bronchioles directly to nearby alveoli.

Alveolar Macrophages

Phagocytic cells that move across alveolar surfaces to digest foreign particles and microorganisms, keeping the alveolar space sterile.