HUMHIS LEC ENDTERM - RESPIRATORY SYSTEM

Respiratory System

The system of organs and tissues involved in oxygen uptake from the atmosphere and carbon dioxide release generated during aerobic respiration.

Breathing (External Respiration)

The process of gas exchange that maintains the body's oxygen supply and removes waste gases.

Conducting Portion

The functional division consisting of the nasal cavities, nasopharynx, larynx, trachea, bronchi, and terminal bronchioles that cleans, warms, humidifies, and conducts air.

Respiratory Portion

The functional division consisting of respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli where gas exchange actually occurs.

Nose and Nasal Cavity

The primary entry point for air that filters incoming air, removes dust and particles, warms and humidifies air, and contains olfactory receptors.

Vestibule

The anterior region of the nasal cavity lined with stratified squamous epithelium containing vibrissae to trap large particles.

Vibrissae

Thick hairs located in the nasal vestibule that trap large inhaled particles.

Respiratory Region (Nasal Cavity)

The main region of the nasal cavity lined with pseudostratified ciliated columnar epithelium responsible for warming and moistening air.

Ciliated Cells

Cells in the respiratory epithelium equipped with cilia that actively move mucus along the respiratory tract.

Goblet Cells

Specialized mucus-secreting epithelial cells found throughout the respiratory mucosa.

Brush Cells

Columnar cells with microvilli in the respiratory epithelium that function as sensory receptors.

Small Granule (Kulchitsky) Cells

Epithelial cells of the respiratory tract that perform neuroendocrine functions.

Basal Cells

Short stem cells attached to the basement membrane that differentiate into other respiratory epithelial cell types.

Mucociliary Escalator

The functional defense mechanism in the lamina propria consisting of mucus and cilia to trap and clear inhaled debris.

Bowman's Glands

Serous glands located in the lamina propria of the olfactory region that secrete fluid to dissolve odorants.

Pharynx (Throat)

The muscular passage connecting the nasal cavity and mouth to the trachea, serving as a common pathway for both air and food.

Nasopharynx

The upper portion of the pharynx behind the nasal cavity lined with pseudostratified ciliated columnar epithelium.

Oropharynx

The middle portion of the pharynx continuous with the oral cavity, lined with stratified squamous epithelium for food passage.

Epiglottis

A flap-like elastic cartilage structure in the pharynx that prevents food and liquids from entering the trachea during swallowing.

Larynx (Voice Box)

A short (4 cm × 4 cm) segment connecting the pharynx to the trachea that allows airflow while preventing food from blocking the airway.

Vestibular Folds

The false vocal cords of the larynx lined primarily with respiratory epithelium containing numerous seromucous glands.

Vocal Folds

The true vocal cords covered by stratified squamous epithelium over the vocalis ligament and vocalis muscle.

Vocalis Muscle

The skeletal muscle layer within the vocal folds that controls cord tension.

Trachea (Windpipe)

A wide, hollow tube connecting the larynx to the main bronchi that conditions air temperature and humidity.

C-shaped Hyaline Cartilage Rings

Rigid cartilaginous structures that reinforce the tracheal wall and keep the tracheal lumen open.

Trachealis Muscle

Smooth muscle filling the posterior gap of the tracheal cartilage rings.

Primary (Main) Bronchi

The right and left main airway branches extending from the trachea that enter the lungs at the hilum.

Secondary (Lobar) Bronchi

Airway branches supplying individual lung lobes (3 on the right, 2 on the left) featuring irregular cartilage plates.

Tertiary (Segmental) Bronchi

Airway branches supplying specific bronchopulmonary segments with smaller diameters and more smooth muscle.

Bronchioles

Intralobular airways 1 mm or less in diameter formed after about 10 generations of branching that lack cartilage and mucosal glands.

Terminal Bronchioles

The final segment of the conducting zone lined by simple cuboidal epithelium with abundant club cells and no gas exchange.

Club (Clara) Cells

Dome-shaped cells in terminal bronchioles that secrete surfactant-like lipoproteins and anti-inflammatory proteins, detoxify toxins, and act as stem cells.

Respiratory Bronchioles

The first segment of the respiratory portion containing scattered alveoli budding directly from their walls.

Alveolar Ducts

Passageways connecting respiratory bronchioles to alveolar sacs whose walls are composed almost entirely of alveoli.

Alveoli

Tiny, thin-walled air sacs (~300 million total) where gas exchange between air and the bloodstream occurs.

Type I Pneumocytes

Extremely thin, simple squamous alveolar cells covering 95% of the alveolar surface joined by tight junctions for gas exchange.

Type II Pneumocytes

Cuboidal alveolar cells with foamy cytoplasm that secrete pulmonary surfactant from lamellar bodies and act as stem cells.

Alveolar Macrophages ("Dust Cells")

Phagocytic cells residing in alveoli and septa that engulf inhaled particulates and RBCs.

Pores of Kohn

Openings in the interalveolar septa that allow pressure equalization and collateral ventilation between adjacent alveoli.

Internal Respiration

The physiological process where oxygen is delivered to body tissues and carbon dioxide is removed and returned to the lungs.