7.7.6: Key Terms

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alveolar $P_{O_{2}}$: partial pressure of oxygen in the alveoli (usually around 100 mmHg)

alveolar duct: duct that extends from the terminal bronchiole to the alveolar sac

alveolar sac: structure consisting of two or more alveoli that share a common opening

alveolar ventilation: how much air is in the alveoli

alveolus: (plural: alveoli) (also, air sac) terminal region of the lung where gas exchange occurs

anatomical dead space: (also, anatomical shunt) region of the lung that lacks proper ventilation/perfusion due to an anatomical block

bicarbonate ${(HCO}_{3}^{-})$ ion: ion created when carbonic acid dissociates into H⁺ and ${(HCO}_{3}^{-})$

bicarbonate buffer system: system in the blood that absorbs carbon dioxide and regulates pH levels

bronchiole: airway that extends from the main tertiary bronchi to the alveolar sac

bronchus: (plural: bronchi) smaller branch of cartilaginous tissue that stems off of the trachea; air is funneled through the bronchi to the region where gas exchange occurs in alveoli

carbaminohemoglobin: molecule that forms when carbon dioxide binds to hemoglobin

carbonic anhydrase (CA): enzyme that catalyzes carbon dioxide and water into carbonic acid

chloride shift: exchange of chloride for bicarbonate into or out of the red blood cell

compliance: measurement of the elasticity of the lung

dead space: area in the lung that lacks proper ventilation or perfusion

diaphragm: domed-shaped skeletal muscle located under lungs that separates the thoracic cavity from the abdominal cavity

elastic recoil: property of the lung that drives the lung tissue inward

elastic work: work conducted by the intercostal muscles, chest wall, and diaphragm

expiratory reserve volume (ERV): amount of additional air that can be exhaled after a normal exhalation

FEV1/FVC ratio: ratio of how much air can be forced out of the lung in one second to the total amount that is forced out of the lung; a measurement of lung function that can be used to detect disease states

flow-resistive: work of breathing performed by the alveoli and tissues in the lung

forced expiratory volume (FEV): (also, forced vital capacity) measure of how much air can be forced out of the lung from maximal inspiration over a specific amount of time

functional residual capacity (FRC): expiratory reserve volume plus residual volume

functional vital capacity (FVC): amount of air that can be forcibly exhaled after taking the deepest breath possible

heme group: centralized iron-containing group that is surrounded by the alpha and beta subunits of hemoglobin

hemoglobin: molecule in red blood cells that can bind oxygen, carbon dioxide, and carbon monoxide

inspiratory capacity (IC): tidal volume plus inspiratory reserve volume

inspiratory reserve volume (IRV): amount of additional air that can be inspired after a normal inhalation

intercostal muscle: muscle connected to the rib cage that contracts upon inspiration

intrapleural space: space between the layers of pleura

larynx: voice box, a short passageway connecting the pharynx and the trachea

lung capacity: measurement of two or more lung volumes (how much air can be inhaled from the end of an expiration to maximal capacity)

lung volume: measurement of air for one lung function (normal inhalation or exhalation)

mucin: complex glycoprotein found in mucus

mucus: sticky protein-containing fluid secretion in the lung that traps particulate matter to be expelled from the body

nasal cavity: opening of the respiratory system to the outside environment

obstructive disease: disease (such as emphysema and asthma) that arises from obstruction of the airways; compliance increases in these diseases

oxygen dissociation curve: curve depicting the affinity of oxygen for hemoglobin

oxygen-carrying capacity: amount of oxygen that can be transported in the blood

partial pressure: amount of pressure exerted by one gas within a mixture of gases

particulate matter: small particle such as dust, dirt, viral particles, and bacteria that are in the air

pharynx: throat; a tube that starts in the internal nares and runs partway down the neck, where it opens into the esophagus and the larynx

physiological dead space: (also, physiological shunt) region of the lung that lacks proper ventilation/perfusion due to a physiological change in the lung (like inflammation or edema)

pleura: tissue layer that surrounds the lungs and lines the interior of the thoracic cavity

pleurisy: painful inflammation of the pleural tissue layers

primary bronchus: (also, main bronchus) region of the airway within the lung that attaches to the trachea and bifurcates to each lung where it branches into secondary bronchi

recruitment: process of opening airways that normally remain closed when the cardiac output increases

residual volume (RV): amount of air remaining in the lung after a maximal expiration

resistance: measurement of lung obstruction

respiratory bronchiole: terminal portion of the bronchiole tree that is attached to the terminal bronchioles and alveoli ducts, alveolar sacs, and alveoli

respiratory distress syndrome: disease that arises from a deficient amount of surfactant

respiratory quotient (RQ): ratio of carbon dioxide production to each oxygen molecule consumed

respiratory rate: number of breaths per minute

restrictive disease: disease that results from a restriction and decreased compliance of the alveoli; respiratory distress syndrome and pulmonary fibrosis are examples

sickle cell anemia: genetic disorder that affects the shape of red blood cells, and their ability to transport oxygen and move through capillaries

spirometry: method to measure lung volumes and to diagnose lung diseases

surfactant: detergent-like liquid in the airways that lowers the surface tension of the alveoli to allow for expansion

terminal bronchiole: region of bronchiole that attaches to the respiratory bronchioles

thalassemia: rare genetic disorder that results in mutation of the alpha or beta subunits of hemoglobin, creating smaller red blood cells with less hemoglobin

tidal volume (TV): amount of air that is inspired and expired during normal breathing

total lung capacity (TLC): sum of the residual volume, expiratory reserve volume, tidal volume, and inspiratory reserve volume

trachea: cartilaginous tube that transports air from the larynx to the primary bronchi

venous $P_{{CO}_{2}}$: partial pressure of carbon dioxide in the veins (40 mm Hg in the pulmonary veins)

venous $P_{O_{2}}$: partial pressure of oxygen in the veins (100 mm Hg in the pulmonary veins)

ventilation/perfusion (V/Q) mismatch: region of the lung that lacks proper alveolar ventilation (V) and/or arterial perfusion (Q)

vital capacity (VC): sum of the expiratory reserve volume, tidal volume, and inspiratory reserve volume