- acclimatization
- process of adjustment that the respiratory system makes due to chronic exposure to high altitudes
- acute mountain sickness (AMS)
- condition that occurs a result of acute exposure to high altitude due to a low partial pressure of oxygen
- 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 dead space
- air space within alveoli that are unable to participate in gas exchange
- 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
- anatomical dead space
- air space present in the airway that never reaches the alveoli and therefore never participates in gas exchange
- apex
- tip of the external nose
- apneustic center
- network of neurons within the pons that stimulate the neurons in the dorsal respiratory group; controls the depth of inspiration
- atmospheric pressure
- amount of force that is exerted by gases in the air surrounding any given surface
- Bohr effect
- relationship between blood pH and oxygen dissociation from hemoglobin
- Boyle’s law
- relationship between volume and pressure as described by the formula: P1V1 = P2V2
- bridge
- portion of the external nose that lies in the area of the nasal bones
- bronchial bud
- structure in the developing embryo that forms when the laryngotracheal bud extends and branches to form two bulbous structures
- bronchial tree
- collective name for the multiple branches of the bronchi and bronchioles of the respiratory system
- bronchiole
- branch of bronchi that are 1 mm or less in diameter and terminate at alveolar sacs
- bronchoconstriction
- decrease in the size of the bronchiole due to relaxation of the muscular wall
- bronchodilation
- increase in the size of the bronchiole due to contraction of the muscular wall
- bronchus
- tube connected to the trachea that branches into many subsidiaries and provides a passageway for air to enter and leave the lungs
- carbaminohemoglobin
- bound form of hemoglobin and carbon dioxide
- carbonic anhydrase (CA)
- enzyme that catalyzes the reaction that causes carbon dioxide and water to form carbonic acid
- cardiac notch
- indentation on the surface of the left lung that allows space for the heart
- central chemoreceptor
- one of the specialized receptors that are located in the brain that sense changes in hydrogen ion, oxygen, or carbon dioxide concentrations in the brain
- chloride shift
- facilitated diffusion that exchanges bicarbonate (HCO3–) with chloride (Cl–) ions
- 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
- Dalton’s law
- statement of the principle that a specific gas type in a mixture exerts its own pressure, as if that specific gas type was not part of a mixture of gases
- dorsal respiratory group (DRG)
- region of the medulla oblongata that stimulates the contraction of the diaphragm and intercostal muscles to induce inspiration
- 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
- expiration
- (also, exhalation) process that causes the air to leave the lungs
- expiratory reserve volume (ERV)
- amount of air that can be forcefully exhaled after a normal tidal exhalation
- external nose
- region of the nose that is easily visible to others
- external respiration
- gas exchange that occurs in the alveoli
- 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
- forced breathing
- (also, hyperpnea) mode of breathing that occurs during exercise or by active thought that requires muscle contraction for both inspiration and expiration
- foregut
- endoderm of the embryo towards the head region
- functional residual capacity (FRC)
- sum of ERV and RV, which is the amount of air that remains in the lungs after a tidal expiration
- glottis
- opening between the vocal folds through which air passes when producing speech
- Haldane effect
- relationship between the partial pressure of oxygen and the affinity of hemoglobin for carbon dioxide
- Henry’s law
- statement of the principle that the concentration of gas in a liquid is directly proportional to the solubility and partial pressure of that gas
- hilum
- concave structure on the mediastinal surface of the lungs where blood vessels, lymphatic vessels, nerves, and a bronchus enter the lung
- hyperpnea
- increased rate and depth of ventilation due to an increase in oxygen demand that does not significantly alter blood oxygen or carbon dioxide levels
- hyperventilation
- increased ventilation rate that leads to abnormally low blood carbon dioxide levels and high (alkaline) blood pH
- inspiration
- (also, inhalation) process that causes air to enter the lungs
- inspiratory capacity (IC)
- sum of the TV and IRV, which is the amount of air that can maximally be inhaled past a tidal expiration
- inspiratory reserve volume (IRV)
- amount of air that enters the lungs due to deep inhalation past the tidal volume
- internal respiration
- gas exchange that occurs at the level of body tissues
- intra-alveolar pressure
- (intrapulmonary pressure) pressure of the air within the alveoli
- intrapleural pressure
- pressure of the air within the pleural cavity
- laryngeal prominence
- region where the two lamine 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
- laryngotracheal
- bud forms from the lung bud, has a tracheal end and bulbous bronchial buds at the distal end
- 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
- lung bud
- median dome that forms from the endoderm of the foregut
- 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
- olfactory pit
- invaginated ectodermal tissue in the anterior portion of the head region of an embryo that will form the nasal cavity
- oropharynx
- portion of the pharynx flanked by the nasopharynx, oral cavity, and laryngopharynx that is a passageway for both air and food
- oxygen–hemoglobin dissociation curve
- graph that describes the relationship of partial pressure to the binding and disassociation of oxygen to and from heme
- oxyhemoglobin
- (Hb–O2) bound form of hemoglobin and oxygen
- 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
- partial pressure
- force exerted by each gas in a mixture of gases
- peripheral chemoreceptor
- one of the specialized receptors located in the aortic arch and carotid arteries that sense changes in pH, carbon dioxide, or oxygen blood levels
- 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
- pneumotaxic center
- network of neurons within the pons that inhibit the activity of the neurons in the dorsal respiratory group; controls rate 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
- pulmonary ventilation
- exchange of gases between the lungs and the atmosphere; breathing
- quiet breathing
- (also, eupnea) mode of breathing that occurs at rest and does not require the cognitive thought of the individual
- residual volume (RV)
- amount of air that remains in the lungs after maximum exhalation
- respiratory bronchiole
- specific type of bronchiole that leads to alveolar sacs
- respiratory cycle
- one sequence of inspiration and expiration
- 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 rate
- total number of breaths taken each minute
- respiratory volume
- varying amounts of air within the lung at a given time
- respiratory zone
- includes structures of the respiratory system that are directly involved in gas exchange
- root
- region of the external nose between the eyebrows
- thoracic wall compliance
- ability of the thoracic wall to stretch while under pressure
- thyroid cartilage
- largest piece of cartilage that makes up the larynx and consists of two lamine
- tidal volume (TV)
- amount of air that normally enters the lungs during quiet breathing
- total dead space
- sum of the anatomical dead space and alveolar dead space
- total lung capacity (TLC)
- total amount of air that can be held in the lungs; sum of TV, ERV, IRV, and RV
- total pressure
- sum of all the partial pressures of a gaseous mixture
- 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
- transpulmonary pressure
- pressure difference between the intrapleural and intra-alveolar pressures
- 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
- ventilation
- movement of air into and out of the lungs; consists of inspiration and expiration
- ventral respiratory group (VRG)
- region of the medulla oblongata that stimulates the contraction of the accessory muscles involved in respiration to induce forced inspiration and expiration
- 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
- vital capacity (VC)
- sum of TV, ERV, and IRV, which is all the volumes that participate in gas exchange