Sections
Key Terms

Key Terms

alveolar $PO2PO2$
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
(also, anatomical shunt) region of the lung that lacks proper ventilation/perfusion due to an anatomical block
bicarbonate $(HCO3−)(HCO3−)$ ion
ion created when carbonic acid dissociates into H+ and $(HCO3−)(HCO3−)$
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
chloride shift exchange of chloride for bicarbonate into or out of the red blood cell
compliance
measurement of the elasticity of the lung
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
(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 $PCO2PCO2$
partial pressure of carbon dioxide in the veins (40 mm Hg in the pulmonary veins)
venous $PO2PO2$
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