Glossary: The Respiratory System


ala (plural = alae) small, flaring structure of a nostril that forms the lateral side of the nares

alar cartilage cartilage that supports the apex of the nose and helps shape the nares; it is connected to the septal cartilage and connective tissue of the alae

alveolar duct small tube that leads from the terminal bronchiole to the respiratory bronchiole and is the point of attachment for alveoli

alveolar macrophage immune system cell of the alveolus that removes debris and pathogens

alveolar pore opening that allows airflow between neighboring alveoli

alveolar sac cluster of alveoli

alveolus small, grape-like sac that performs gas exchange in the lungs

apex tip of the external nose

bronchial tree collective name for the multiple branches of the bronchi and bronchioles of the respiratory system

bronchoconstriction decrease in the size of the bronchiole due to contraction of the muscular wall

bronchodilation increase in the size of the bronchiole due to contraction of the muscular wall

bridge portion of the external nose that lies in the area of the nasal bones

bronchiole branch of bronchi that are 1 mm or less in diameter and terminate at alveolar sacs

bronchus tube connected to the trachea that branches into many subsidiaries and provides a passageway for air to enter and leave the lungs

cardiac notch indentation on the surface of the left lung that allows space for the heart

conducting zone region of the respiratory system that includes the organs and structures that provide passageways for air and are not directly involved in gas exchange

cricoid cartilage portion of the larynx composed of a ring of cartilage with a wide posterior region and a thinner anterior region; attached to the esophagus

dorsum nasi intermediate portion of the external nose that connects the bridge to the apex and is supported by the nasal bone

epiglottis leaf-shaped piece of elastic cartilage that is a portion of the larynx that swings to close the trachea during swallowing

external nose region of the nose that is easily visible to others

fauces portion of the posterior oral cavity that connects the oral cavity to the oropharynx

fibroelastic membrane specialized membrane that connects the ends of the C-shape cartilage in the trachea; contains smooth muscle fibers

glottis opening between the vocal folds through which air passes when producing speech

hilum concave structure on the mediastinal surface of the lungs where blood vessels, lymphatic vessels, nerves, and a bronchus enter the lung

laryngeal prominence region where the two lamina of the thyroid cartilage join, forming a protrusion known as “Adam’s apple”

laryngopharynx portion of the pharynx bordered by the oropharynx superiorly and esophagus and trachea inferiorly; serves as a route for both air and food

larynx cartilaginous structure that produces the voice, prevents food and beverages from entering the trachea, and regulates the volume of air that enters and leaves the lungs

lingual tonsil lymphoid tissue located at the base of the tongue

lung organ of the respiratory system that performs gas exchange

meatus one of three recesses (superior, middle, and inferior) in the nasal cavity attached to the conchae that increase the surface area of the nasal cavity

naris (plural = nares) opening of the nostrils

nasal bone bone of the skull that lies under the root and bridge of the nose and is connected to the frontal and maxillary bones

nasal septum wall composed of bone and cartilage that separates the left and right nasal cavities

nasopharynx portion of the pharynx flanked by the conchae and oropharynx that serves as an airway

oropharynx portion of the pharynx flanked by the nasopharynx, oral cavity, and laryngopharynx that is a passageway for both air and food

palatine tonsil one of the paired structures composed of lymphoid tissue located anterior to the uvula at the roof of isthmus of the fauces

paranasal sinus one of the cavities within the skull that is connected to the conchae that serve to warm and humidify incoming air, produce mucus, and lighten the weight of the skull; consists of frontal, maxillary, sphenoidal, and ethmoidal sinuses

parietal pleura outermost layer of the pleura that connects to the thoracic wall, mediastinum, and diaphragm

pharyngeal tonsil structure composed of lymphoid tissue located in the nasopharynx

pharynx region of the conducting zone that forms a tube of skeletal muscle lined with respiratory epithelium; located between the nasal conchae and the esophagus and trachea

philtrum concave surface of the face that connects the apex of the nose to the top lip

pleural cavity space between the visceral and parietal pleurae

pleural fluid substance that acts as a lubricant for the visceral and parietal layers of the pleura during the movement of breathing

pulmonary artery artery that arises from the pulmonary trunk and carries deoxygenated, arterial blood to the alveoli

pulmonary plexus network of autonomic nervous system fibers found near the hilum of the lung

pulmonary surfactant substance composed of phospholipids and proteins that reduces the surface tension of the alveoli; made by type II alveolar cells

respiratory bronchiole specific type of bronchiole that leads to alveolar sacs

respiratory epithelium ciliated lining of much of the conducting zone that is specialized to remove debris and pathogens, and produce mucus

respiratory membrane alveolar and capillary wall together, which form an air-blood barrier that facilitates the simple diffusion of gases

respiratory zone includes structures of the respiratory system that are directly involved in gas exchange

root region of the external nose between the eyebrows

thyroid cartilage largest piece of cartilage that makes up the larynx and consists of two lamina

trachea tube composed of cartilaginous rings and supporting tissue that connects the lung bronchi and the larynx; provides a route for air to enter and exit the lung

trachealis muscle smooth muscle located in the fibroelastic membrane of the trachea

true vocal cord one of the pair of folded, white membranes that have a free inner edge that oscillates as air passes through to produce sound

type I alveolar cell squamous epithelial cells that are the major cell type in the alveolar wall; highly permeable to gases

type II alveolar cell cuboidal epithelial cells that are the minor cell type in the alveolar wall; secrete pulmonary surfactant

vestibular fold part of the folded region of the glottis composed of mucous membrane; supports the epiglottis during swallowing

visceral pleura innermost layer of the pleura that is superficial to the lungs and extends into the lung fissures