Vocabulary Respiratory System

Active breathing – A type of breathing that involves conscious effort, engaging accessory muscles for deeper or more forceful inhalation and exhalation, such as during exercise.

Air flow – The movementA fundamental property of life involving motion of the body or its parts. of air into and out of the respiratory tract, driven by pressureThe force exerted by gases in the respiratory system, affecting airflow and gas exchange. differences between the atmosphere and the lungs.

Alveolar pores – Small openings between adjacent alveoliMicroscopic air sacs in the lungs where gas exchange occurs between air and blood. that allow air to circulate between them, helping to equalize pressure.

Alveolar surface tension – The force exerted by the liquid lining the alveoli, which tends to collapse them; reduced by surfactantA substance secreted by Type II pneumocytes that reduces alveolar surface tension. to keep alveoli open.

Alveolar macrophages – Immune cellsThe basic structural and functional units of life. found in the alveoli that engulf and digest pathogens, debris, and dust particles.

Alveoli – Microscopic air sacs in the lungs where gas exchange occurs between air and blood.

Asthma – A chronic condition characterized by airway inflammation, narrowing, and excessive mucus production, leading to difficulty breathing.

Bicarbonate (HCO₃⁻) – A crucial buffer in blood that helps maintain pHA measure of hydrogen ion concentration in a solution. balance; formed when carbon dioxide reacts with waterThe universal solvent essential for life. in the blood.

Boyle’s Law – States that at constant temperature, the pressure of a gas is inversely proportional to its volume (as lung volume increases, pressure decreases, allowing air to enter).

Bronchi – The large airways that branch from the trachea into the lungs, dividing into smaller bronchiolesSmall airways branching from the bronchi that lead to alveoli; lack cartilage and control airflow wi.

Bronchioles – Small airways branching from the bronchiThe large airways that branch from the trachea into the lungs, dividing into smaller bronchioles. that lead to alveoli; lack cartilageA flexible connective tissue found in joints, the ear, nose, and rib cage. Cartilage can be of three and control airflow with smooth muscle.

Bronchitis – Inflammation of the bronchi, leading to mucus buildup, coughing, and breathing difficulties.

Bronchopulmonary segmentsThe subdivisions of lung lobes, supplied by tertiary bronchi. – Functional units of the lungs, each served by its own tertiary bronchus and blood supply.

Carbonic acidA substance that releases hydrogen ions (H⁺) in solution. (H₂CO₃) – A weak acid formed when carbon dioxide dissolves in water; plays a key role in blood pH regulation.

Cardiac notch – A concave space on the left lung that accommodates the heart.

Charles’s Law – States that gas volume is directly proportional to temperature at constant pressure (warmer air expands in the lungs).

Cilia – Hair-like structures lining the respiratory tract that move mucus and trapped particles out of the airways.

Compliance – The ease with which the lungs expand and contract during breathing.

Conchae – Curved bony structures in the nasal cavityThe internal space behind the nose that filters, warms, and humidifies incoming air. that increase surface area and help warm, humidify, and filter air.

Dalton’s Law – States that the total pressure of a gas mixture is the sum of the partial pressures of its individual gases.

Deoxyhemoglobin – Hemoglobin that has released its oxygen and is carrying carbon dioxide or hydrogen ionsCharged atoms or molecules..

Elastic cartilage – A flexible type of cartilage found in structures like the epiglottisA flap of cartilage that covers the trachea during swallowing to prevent food from entering the airw that helps maintain shape.

Emphysema – A lung disease in which alveoli are damaged, reducing surface area for gas exchange and causing shortness of breath.

Epiglottis – A flap of cartilage that covers the trachea during swallowing to prevent food from entering the airway.

Expiration – The process of exhaling, which can be passive (relaxation of respiratory muscles) or active (involving abdominal and intercostal muscles).

Expiratory reserve volume (ERV) – The additional amount of air that can be forcibly exhaled after a normal exhalation.

External intercostals – Muscles between the ribsCurved bones forming the rib cage; articulate with thoracic vertebrae and most with the sternum. that assist with inspirationThe process of inhaling, driven by diaphragm and external intercostal contraction. by expanding the ribcage.

External respirationThe process of gas exchange, including ventilation, external and internal respiration. – The exchange of gases between the lungs and the blood in the pulmonary capillariesThe smallest blood vessels where gas, nutrient, and waste exchange occurs between blood and tissues..

Forced vital capacity (FVC) – The maximum amount of air a person can forcibly exhale after a deepAway from the surface of the body. inhalation.

Functional residual capacity (FRC) – The volume of air remaining in the lungs after a normal exhalation.

Henry’s Law – States that the amount of gas dissolved in a liquid is proportional to its partial pressureThe pressure exerted by a single gas in a mixture; drives diffusion in respiration. and solubility.

Hyaline cartilage – The supportive, flexible cartilage that reinforces structures like the trachea and bronchi.

Inspiration – The process of inhaling, driven by diaphragm and external intercostal contraction.

Inspiratory reserve volume (IRV) – The additional volume of air that can be inhaled beyond a normal breath.

Inspiratory capacity – The maximum volume of air that can be inhaled after a normal exhalation.

Internal respiration – The exchange of gases between the blood and body tissues.

Intrapleural pressure – The pressure within the pleural cavity; normally negative to keep the lungs expanded.

Intrapulmonary pressure – The pressure within the alveoli; fluctuates during breathing and equalizes with atmospheric pressure.

Larynx – The voice box; contains vocal cords and connects the pharynxThe muscular passageway connecting the mouth to the esophagus and larynx. to the trachea.

Lobes – The divisions of the lungs (right lung has three lobes, left lung has two).

Lower respiratory tract – The portion of the respiratory systemThe organ system responsible for gas exchange (oxygen and carbon dioxide). including the trachea, bronchi, lungs, and alveoli.

Meatuses – Air passageways between the nasal conchaeCurved, scroll-like bones inside nasal cavity; increase surface area for air warming and filtration. that direct airflow through the nasalTwo small rectangular bones forming the bridge of the nose. cavity.

Mucociliary escalator – The mechanism by which ciliaHair-like projections on the surface of some cells that move fluids or particles. move mucus and trapped particles up toward the throat for removal.

Nasal cavity – The internal space behind the nose that filters, warms, and humidifies incoming air.

Obstructive disorders – Respiratory conditions (e.g., asthmaA chronic condition characterized by airway inflammation, narrowing, and excessive mucus production,, COPD) that make exhaling difficult due to narrowed airways.

Oxygen affinity – The tendency of hemoglobinThe oxygen-carrying protein in red blood cells that gives blood its red color. to bind to oxygen; affected by pH, temperature, and CO₂ levels.

Oxygen saturation – The percentage of hemoglobin moleculesGroups of atoms bonded together. carrying oxygen.

Oxyhemoglobin – Hemoglobin bound to oxygen, transporting it from the lungs to tissues.

Parietal pleuraThe double-layered membrane surrounding the lungs and lining the thoracic cavity. – The outer layer of the pleura that lines the thoracic cavityThe body cavity housing the heart and lungs..

Partial pressure – The pressure exerted by a single gas in a mixture; drives diffusionPassive movement of molecules from areas of high to low concentration. in respiration.

Pharynx – The throat; connects the nasal cavity and mouthThe opening of the digestive tract where food enters and mastication begins. to the larynxThe voice box; contains vocal cords and connects the pharynx to the trachea. and esophagusThe muscular tube that transports food from the pharynx to the stomach via peristalsis..

Pleura – The double-layered membrane surrounding the lungs and lining the thoracic cavity.

Pneumonia – A lung infection causing inflammation and fluid buildup in the alveoli.

Pressure – The force exerted by gases in the respiratory system, affecting airflow and gas exchange.

Primary bronchi – The first branches of the trachea that lead into the lungs.

Primary muscles – The diaphragm and external intercostalsElevator Between ribs; lifts rib cage during breathing in., responsible for quiet breathingNormal, passive breathing at rest..

Quiet breathing – Normal, passive breathing at rest.

Residual volume (RV) – The amount of air remaining in the lungs after maximal exhalation.

Resistance – The opposition to airflow in the respiratory tract, influenced by airway diameter.

Respiration – The process of gas exchange, including ventilation, external and internal respirationThe exchange of gases between the blood and body tissues..

Respiratory bronchioles – Smallest bronchioles leading to alveolar ducts and alveoli.

Restrictive disorders – Lung conditions (e.g., fibrosis) that reduce lung expansion and lung volume.

Secondary bronchi – Branches from the primary bronchiThe first branches of the trachea that lead into the lungs. Also called lobar bronchi that lead to each lung lobe.

Secondary muscles – Accessory muscles used during forced breathing, such as sternocleidomastoidFlexor / Rotator From sternum and clavicle to skull behind the ear; turns and bends the head..

Segments – The subdivisions of lung lobes, supplied by tertiary bronchiBranches from the secondary bronchi that serve bronchopulmonary segments..

Sinuses – Air-filled spaces in the skull that lighten it and help humidify air.

Submucosal glands – Glands in the airway walls that secrete mucus.

Surfactant – A substance secreted by Type II pneumocytes that reduces alveolar surface tensionThe force exerted by the liquid lining the alveoli, which tends to collapse them; reduced by surfact.

Terminal bronchioles – The last portion of the conducting airway before respiratory bronchiolesSmallest bronchioles leading to alveolar ducts and alveoli..

Tertiary bronchi – Branches from the secondary bronchiBranches from the primary bronchi that lead to each lung lobe. Also called segmental bronchi that serve bronchopulmonary segmentsFunctional units of the lungs, each served by its own tertiary bronchus and blood supply..

Tidal volume – The amount of air inhaled or exhaled in a normal breath.

Total lung capacity (TLC) – The total volume of air the lungs can hold.

Trachea – The windpipe; connects the larynx to the bronchi.

Tracheal cartilages – C-shaped rings that support the trachea and keep it open.

Tuberculosis (TB) – A bacterial infection that primarily affects the lungs, causing inflammation and scarring.

Type I pneumocytes – Thin cells that form the alveolar walls, allowing for gas exchange.

Type II pneumocytes – Cells that produce surfactant to reduce alveolar surface tension.

Upper respiratory tract – The portion of the respiratory system including the nose, nasal cavity, pharynx, and larynx.

Ventilation – The movement of air in and out of the lungs.

Vibrissae – Nose hairs that help trap particles and debris.

Visceral pleura – The inner layer of the pleura that covers the lungs.

Volume – The amount of air in the lungs, measured in various capacities and reserves.