Accessory Muscles of Respiration:
Muscles that are
generally not used in regular breathing, but that can be
recruited to assist in breathing during an acute attack of
dyspnea (shortness of breath).
Acinus: A cluster of alveoli at the end of a tiny
respiratory airway in the lung.
Acute: An adjective that is generally used to refer to
an event of sudden or severe onset and short duration.
Airway Epithelium: The layer of cells that line the
airways. These are called epithelial cells and consist of five
major types and a number of minor cell types. The major cell
types are ciliated, basal, goblet, serous
Airways: Tubular structures within the neck (trachea)
and lungs (bronchi, bronchioles, bronchioli) that allow passage
of air into and out of the lungs.
Alveolar Macrophages: Mobile cells that normally
reside within alveoli and perform a
number of critical functions in health and disease. Alveolar
macrophages serve a critical function in surfactant homeostasis by removing excess surfactant lipids
and surfactant proteins from the alveoli. They also protect the
lung by internalizing and destroying inhaled microbial organisms
(e.g., bacteria), and by removing inhaled particulates. Alveolar
macrophages also participate in inflammation, repair of damaged
lung tissues, eliminating cancer cells and a number of other
Alveoli: Tiny sac-like air spaces in the lungs where
transfer of carbon dioxide from blood into the lungs and
oxygen from air into blood takes place.
Antibiotic: A class of drugs that either inhibit the
growth of or kill microbial pathogens like bacterial, fungal or
Antibodies: Protective proteins produced by the immune
system that recognize and bind to foreign molecules (antigens).
Anti-cholinergic:A class of drugs blocks (opposes the
action of) acetylcholine, a protein that transmits nerve
impulses between nerve cells. In emphysema,
anti-cholinergic drugs are used to block nerve impulses to the
muscles in the walls of the respiratory airways.
Arterial Blood Gas (ABG): A test in which blood is
taken from an artery and used to determine the amounts of
oxygen and carbon dioxide in the blood.
Arteriole: The smallest artery; it connects larger
arteries to the capillary network.
Artery: A blood vessel that carries blood away from
the heart and towards a part of the body.
Asthma: A lung disease characterized by narrowing of
the respiratory airways. Symptoms include recurrent attacks of
wheezing, coughing, shortness of breath (dyspnea).
b.i.d.: An abbreviation for the Latin term "bis in
di'e", meaning twice a day
Beta 2 Agonist: A type of drug that relaxes the
muscles within the respiratory airway thus allowing the airways
to expand resulting in relief of dyspnea.
within the lung that usually larger and closer to the throat.
Bronchiole: Respiratory airways within the lungs that
is smaller and farther away from the throat. These are the
smallest air tubes within the lung and branch off of larger
bronchi and join to alveolar ducts, and to
Bronchodilator: A type of drug that relaxes the
muscles within the respiratory airway thus allowing the
airways to expand resulting in relief of
dyspnea. See Beta 2 agonist and steroids.
Bronchopulmonary: Pertaining to the lungs and air
Bronchoscopy: A procedure in which a small, flexible
tube is passed through a nostril or the mouth and into the
larger airways of the lungs. The bronchoscope tube has several
channels including a fiberoptic light path and a suction
channel, which permit direct visualization of the airway
surfaces and collection of lung fluid or tissues, respectively.
Capillaries: The smallest blood vessels in the body. A
network of capillaries in tissues connects arterioles that bring
blood to the tissues with venules that return blood to the
Cell: The smallest unit of a living structure capable
of independent existence, composed of a membrane-enclosed mass of protoplasm and containing a
nucleus or nucleoid.
Chest: The anterior wall of the thorax, the upper part
of the body between the neck and the abdomen.
Chest Cavity: Space in body surrounding the lungs.
Chronic: Referring to a health-related state, lasting
a long time.
Chronic Bronchitis: A respiratory disease
characterized chronic coughing that lasts for more that three
months per year on successive years. It may be accompanied by
changes in structure of the airways of the lungs, inflammation,
and enlargement of the mucous glands.
Chronic Obstructive Pulmonary Disease:
A general term
used for lung diseases with permanent or temporary narrowing of
small bronchi, in which forced expiratory
flow is slowed. It is frequently used when no etiologic or other
more specific term can be applied.
Cilia: Motile extensions of the surface of some airway
epithelial cells that look like short thick hairs and act as
filters in the nose and upper airway, using a wave-like motion.
Collagen: A group of rigid, fibrous proteins that
serve as the main components of connective tissues of the body.
Collagen is usually found in the interstitium between cells.
Computed Tomography (CT) Scan: A test that in which
x-rays are used to create a picture of the body (i.e., a chest
CT scan of the lungs) using a computer-controlled machine (CT
Congenital: Existing at birth.
Contraction Of The Heart: A reduction in the size of
the heart due to shortening of heart muscles fibers; heart
contractions cause blood to flow into the arteries and to the
Cor Pulmonale (right-sided heart failure):
of the heart characterized by enlargement of the right
ventricle. It is caused by increased resistance to blood flow
through the lung and can occur in severe lung disease and lead
to heart failure.
Corticosteroid: A class of steroid-type drugs that are
used to suppress inflammation and function as slow-acting
bronchodilators. Examples include
prednisone, cortisone, fluticasone, beclomethasone, and others.
Steroids are similar to hormones produced in the body's adrenal
glands that serve as chemical messengers.
Crackle: An ambiguous term used by doctors to describe
an abnormal sound heard when listening for breath sounds during
examination of the chest. It is used by some to denote rhonchus
and by others to denote crepitation. It is a synonym for the
A specific term used by doctors to describe an abnormal
sound heard when listening for breath sounds during examination
of the chest. It denotes the a fine bubbling sound that
resembles the noise heard on rubbing hair between the fingers.
Cyanosis: A bluish color of skin, fingernails, and
mucous membranes that indicates low level
of oxygen in the blood.
Diaphragm: The muscle on which the lungs and heart
rest that separates the chest and abdominal cavity and serves as
the primary muscle used for breathing.
pulmonary function test that measures
the ability of the lung to permit the passage of gas into the
Diuretic: A type of drug that promotes the excretion
of salt and water by the kidney and thus increases urine output.
Duct: Tubular structures within the body with
well-defined walls that usually permit passage of air or
Ductus Arteriosus: An arterial
connecting the pulmonary artery to the
descending aorta. It is usually open in the fetus where it allows blood to pass from the pulmonary
artery directly into the aorta thus by passing the lungs, which
are not used for breathing by the fetus (gas exchange for the
fetus occurs in the placenta). It is normally closed after birth
so that blood can pass through the lungs of the breathing
individual before being returned to the heart and aorta for
transport to the body.
Dysplasia: Abnormal growth or development of tissue.
Dyspnea: Difficulty breathing, frequently referred to
as "shortness of breath," "chest tightness" or "hard, labored
Edema: An abnormal swelling resulting from the
excessive accumulation of watery fluid in
interstitial spaces between cells in
tissues of the body.
Elastin: A type of protein that serves as the main
component of elastic fibers in the body.
Emphysema: A chronic lung
disease characterized by destruction of portions of the tissues
distal to the terminal
bronchioles, i.e., those parts containing
alveoli that result in reduced numbers of alveoli and
enlarged alveolar spaces. An important clinical manifestation is
breathlessness on exertion, due to the reduction of alveoli
available for gas exchange and collapse of
small airways and trapping of alveolar
gas on expiration. Air trapping prolongs
expiration, increases the
and causes the chest to become enlarged ("barrel chest").
Endotracheal Tube: An open-ended plastic tube that is
placed within the trachea usually to allow assisted breathing by
Expiration: The act of expelling air from the lung,
i.e., breathing out.
Expiratory Reserve Volume (ERV):
A pulmonary function
test that measures the maximum volume of air expired from the
lung starting from the position at the end of a breath during
Fetus: The unborn offspring of an animal following the
embryonic period, i.e., from 8 weeks after conception until
Forced Expiratory Flow 25-75% : A pulmonary function
test that measures the forced expiraotyr flow during the middle
half of the FVC. This test was previously
referred to as the maximum midexpiratory flow rate.
Forced Expiratory Volume in one second (FEV 1):
pulmonary function test that measures the volume of air expired
during the first second of a forced exhalation from the position
of maximal inspiration.
Forced Vital Capacity (FVC): A pulmonary function test
that measures the maximum volume of air forcibly expired from
the maximum inspiratory position.
Gas Exchange: The process in which
oxygen from inhaled air is transferred into the blood and
carbon dioxide from the blood is transferred into the
alveoli. It is a primary function of the
lung and occurs across the alveolar wall.
Genetic Disease: A disease that passed on to an
individual by genes (DNA) obtained from one or both parents.
Gestation Period: The period of development of the
unborn offspring from the time of conception until birth.
Hemoptysis: Coughing up blood or blood-stained
Hyaline Membrane Disease: A respiratory disease of
newborns in which dead lung cells and proteins form a "membrane"
within the alveoli making
gas exchange difficult or impossible. It
occurs more frequently in infants that are born prematurely
before the lungs are able to make adequate amounts of
Hypertension: High blood pressure.
Hypoxemia: Low levels of
in the blood.
Immunization: A biological drug that stimulates the
immune system to develop protective responses, usually
antibodies, against a specific
infectious organism or group of organisms. Vaccines are frequently made from killed or attenuated
microbial organisms. Newer vaccines are sometimes made from
proteins or DNA purified from microbial organisms.
Inflammation: A natural response of the body to injury
characterized by recruitment of specialized white blood cells
into the tissues, edema and increased
metabolic activity. Inflammation can occur in any part of the
body including the airways; in the skin,
inflammation is accompanied by
swelling, redness, and pain. These
signs also occur during inflammation of the airways and can
be seen during bronchoscopy.
Inspiration: The act of bringing air into the lungs,
i.e. taking in a breath.
Interstitial: The space between the cells of a tissue
or organ, but excluding empty spaces such as body cavities and
potential spaces (e.g., pleural space).
Jaundice: A syndrome (condition) characterized by
hyperbilirubinemia and deposition of bile pigment in the skin
and mucous membranes that result in a
yellow appearance of the patient.
Klebsiella Pneumoniae: A specific type of bacteria,
which causes pneumonia in humans.
Lung Biopsy: A procedure in which a specimen of lung
tissue is taken for examination. Various approaches can be used
to obtain lung biopsies including bronchoscopy, a transthoracic
needle, or surgery.
Lung: One of a pair of viscera (internal organs)
occupying the chest cavity of the thorax
that serve as the organs of respiration
in which gas exchange occurs.
Lymph: A transparent,
slightly yellow liquid found in the lymphatic vessels. Lymph is
collected from tissue fluids throughout the body and returned to
the blood via the lymphatic system.
Mechanical Ventilation: A life-preserving procedure in
which a machine called a mechanical ventilator is used to delivery air to the lungs via an
endotracheal tube. Mechanical ventilation is used in cases where
gas exchange is impaired or lung failure
Membrane: This term has several meanings depending on
the usage. In reference to a cell, the outer or limiting
membrane is the thin, flexible film that encloses the contents
of a cell and is comprised of a double layer of lipids
containing various attached and embedded proteins; it controls
what substances go into and come out of the cell. In reference
to a tissue, the membrane is a thin layer of cells that covers
the surface of the tissue or lines the cavity of an organ.
Metered-Dose Inhaler(MDI): A medication container
that, when activated by pushing a trigger, delivers a
pre-measured dose of medication that is inhaled directly into
Mucociliary Escalator: A mechanism by which
mucous is propelled towards the nose and
eliminated by coughing or sneezing. Cilia
on the surface of the specialized airway epithelial cells form a
thick carpet of fibers that beat in unison and create wave like
movement of a fluid layer that covers the inside surface of the
airway tube. Consequently, the mucous that sits atop this "pericellular"
fluid layer is propelled towards the nose like "mucous
surfboards", carrying their cargo of inhaled microbes and
particulates out of the lungs.
Mucous: A sticky substance produced by specialized
(goblet) cells within the respiratory tract. After synthesis it
is stored in mucous droplets in goblet cells until it is needed,
at which time it is expelled from the cell and sits atop the
pericellular fluid layer that coats the airway epithelium. The
sticky material "catches" inhaled particulates and is then
eliminated from the body by the mucociliary
escalator. Mucous is the major component of phlegm that is
expectorated from the lungs in individuals with a "productive"
cough. Lung diseases associated with airway
and chronic bronchitis, asthma, COPD)
often lead to increased production of mucous.
Mycoplasma pneumoniae: A specific type of bacteria,
which can cause pneumonia.
Nasal Flaring: An outward motion of the nostrils
during breathing; it can be an indication of dyspnea or labored
Neonatal Period: The initial period of life of the
newborn; usually referring to the first 4 weeks after birth.
Neonatologist: A doctor specializing in the care and
treatment of diseases of newborn babies.
Neutrophils: A mobile cell made in large numbers in
the bone marrow and released into the blood. They can be
recruited into the lungs and other tissues by specific
substances released at sites of inflammation to help to protect against infections.
Neutrophils are capable of releasing large amounts of
destructive enzymes that can damage the interstitium and cells
of the tissue, especially when levels of alpha-1 antitrypsin are
very low. In the lungs, this process can lead to
emphysema. Smoking results in increased
recruitment of neutrophils and other molecular events that
damage the tissue and result in emphysema. However, neutrophils
represent a "double-edged sword" because they are vital to the
normal host defense mechanisms.
Osteoporosis: A condition characterized by loss of
bone substance that causes the bones to become porous ("thin")
and fragile. Osteoporosis is most commonly seen in women who are
postmenopausal and by prolonged use of corticosteroids.
Oxygen: A colorless, odorless gas that constitutes 21%
of the air we breathe at sea level. Oxygen combines naturally
with many other elements to form oxides (i.e., rust on iron). It
is essential to life because is provides the energy used to
"power" a wide variety of chemical reactions that occur in the
cells of the body.
Arteriosus: Abnormally persistent opening of the arterial
duct connecting the pulmonary
artery and the aorta. The ductus
arteriosis usually closes within 24 hours of birth thus
preventing blood from bypassing the lungs.
molecular and cellular events that lead to or cause a disease.
Pathophysiology: A term used to describe the abnormal
physiological functioning of an organ, cell or molecular
Peak Expiratory Flow (PEF): A pulmonary function test
that measures the maximum value for the expiratory flow of air
from the lungs during a forced exhalation.
term used to describe the mechanistic functioning of an organ,
cell or molecular process.
Placenta: The organ of metabolic interchange between
the fetus and mother. It is connected to
the fetus by the umbilical cord and to the mother's circulation
via an interface with the womb and is comprised of both
embryonic and maternal tissues. The placenta prevents mixing of
fetal and maternal blood but permits the exchange of
oxygen, carbon dioxide, nutrients from the
mother's blood, and secretes the hormones necessary for
Pleura: The serous
(sheet of cells) covering the surface of the lungs and lining
the inside walls of the chest cavity.
The visceral pleura cover the surface of the lung (one of the
visceral organs, or viscera) and the parietal pleura covers the
inside of the chest wall.
Pleural Cavity: The space between the parietal and
visceral layers of the pleura. The pleural cavity (also called
pleural space) is a potential space, meaning that it is normally
not occupied with anything more that a tiny amount fluid that
serves as a lubricant for the visceral and parietal pleural
surfaces. The pressure within the pleural cavity is normally
negative (i.e., a vacuum) with respect to the atmosphere and
this helps keep the lung inflated to the fullest extent
possible. However, if the lung surface or chest wall is damaged,
air can enter the pleural cavity resulting in collapse of the
lung (see pneumothorax). Fluid can also accumulate in these
spaces (see pleural effusion) and compress the lungs, thus
Pleural Effusion (Pleural Fluid):
accumulation of fluid within the pleural cavity. It can be
consist of watery fluid that accompanies serious heart failure,
inflammatory cells and proteins that accompanies lung infection,
and chylous lymphatic fluid that can occur in
Pneumococcal Vaccine: A drug made from a killed
preparation of a common pneumonia
causing bacteria ( Streptococcus pneumoniae ) that
stimulates a person's immune system to develop specific
antibodies that can recognize and
prevent subsequent infections by this group of bacteria.
Pneumonia: Inflammation of the lung tissues
characterized by filling of the alveolar air spaces with exudate,
inflammatory cells and blood protein (fibrin). Most cases are
due to infection by bacteria or viruses, but some are caused by
inhalation of chemicals or trauma to the chest wall or by
infection by other less common microorganisms.
Pneumothorax: A partial or complete collapse of the
lung resulting from the abnormal entry of gas into the
Positive Pressure Ventilation: A type of assisted
breathing where air, frequently mixed with increased amounts of
oxygen, is delivered under pressure by a
Prenatal: A term referring to the period of life of a
fetus that occurs before birth.
Progressive: A term used to describe the course or
natural history of a disease. It is frequently used, when
unqualified, to indicate an unfavorable course.
Pulmonary: Relating to the lungs or the pulmonary
Pulmonary Edema: An abnormal accumulation of fluid in
the lungs. It can occur in association with severe heart failure
when watery fluid "leaks" out of the pulmonary capillaries into
the interstitium of the lung and, eventually, into the
alveoli and terminal
Pulmonary Hypertension: Abnormally high blood pressure
in the arteries of the lungs.
Pus: A thick, opaque, and usually yellowish/greenish
fluid that contains white blood cells, bits of destroyed tissue,
q.d.: An abbreviation for the Latin term "qua'que di'e",
meaning every day.
q.h.: An abbreviation for the Latin term "qua'que
ho'ra", meaning every hour.
q.i.d.: An abbreviation for the Latin term "qua'ter in
di'e", meaning four times a day.
Rales (crackles): An ambiguous term used by doctors to
describe an abnormal sound heard when listening for breath
sounds during examination of the chest. It is used by some to
denote a rhonchus and by others for crepitation. Such sounds are
created when air moves through airways
that contain fluid.
Residual Volume (RV): A pulmonary function test that
measures the volume of air remaining in the lungs after maximum
Respiration: The process by which
oxygen from the air is exchanged for carbon dioxide produced
by the body. It includes the mechanical process of breathing,
gas exchange in the lungs, and delivery of
oxygen and carbon dioxide via the blood to the
interstitial fluids and into and out
of the cells.
Respiratory Distress Syndrome (RDS):
A lung condition characterized by severe respiratory
insufficiency/failure associated with pulmonary infiltrates
chest x-ray, impaired oxygen absorption, and the absence of
elevated pulmonary arterial
hypertension. The condition can occur in children and adults
(ARDS) and can arise from a variety of pulmonary and other
insults. A similar disease called hyaline
membrane disease also occur in premature infants born before
the lungs have matured to the point where they are able to
produce adequate amounts of surfactant
to prevent lung collapse. In all forms, severe breathlessness is
characteristic and rapidly decompensates to respiratory failure
hypoxemia and cyanosis requiring mechanical
ventilation for survival.
Respiratory Failure: Inability of the lungs to conduct
Respiratory Quotient: Rhe ratio of the volume of
carbon dioxide expired to the volume of oxygen
absorbed by the lungs per unit of time.
Rhonchi: A specific term used to denote an abnormal
sound with a musical pitch occurring during
Risk Factors: Any genetic trait, medical condition,
specific behavior or environmental exposure that is associated
with an increased chance (risk) of an individual developing a
Sign: Any abnormality indicative of a disease,
discoverable on examination of the patient, i.e., an objective
indication of disease.
Spirometry: A set of
functions tests that are performed by breathing into an
instrument called a spirometer, which records the amount and
rate of air that is inhaled and exhaled. Some of the test
measurements are obtained by normal breathing, and other tests
require forced inhalation and/or exhalation.
Sputum: Expectorated material usually consisting
mostly of mucous or mucous mixed with
pus. It is frequently produced in increased
amounts in diseases of the airways, i.e.,
chronic bronchitis or
Streptococcus pneumoniae (pneumococcus):
specific type of bacteria, which is the most common cause of
pneumonia in humans. Pneumococcus
causes death from pneumonia in approximately 40,000 individuals
in the United States each year. The pneumococcal vaccine helps prevent pneumococcus-related
pneumonia and death.
Surfactant: A whitish milky substance consisting of
lipids and proteins that are secreted by type II alveolar
epithelial cells that line the alveoli.
It consists of 90% lipids (mostly phospholipids) and 10%
proteins. There are four main surfactant proteins: surfactant
protein-A (SP-A), SP-B, SP-C, and SP-C. SP-B and SP-C are very
lipid-soluble and serve critical role in a mechanism which
prevents the alveoli from collapsing at
the end of a breath. SP-A and SP-D are more water-soluble and
appear to have important roles in lung host defense.
Symptom: Any phenomenon or departure from the normal
in structure, function, or sensation experienced by the patient
that indicates the presence of a disease, i.e., a subjective
indication of disease.
Symptomatic Treatment: A therapy that reduces the
symptoms of a disease without specifically reducing or
eliminating the cause.
t.i.d.: An abbreviation for the Latin term "ter in
di'e", meaning three times a day.
Thoracentesis: Removal of fluid from the
pleural cavity, usually with a thin
metal or plastic needle inserted between the ribs.
Tidal Volume (VT): A
function test that measures the volume of air inspired or
expired with each breath during quiet breathing.
Total Lung Capacity (TLC): A pulmonary function test
that measures the volume of air inside the lung after maximum
Trachea: The air tube extending from the larynx into
the thorax where it bifurcates (splits) into the right and left
Ultrasound: Mechanical radiant energy with a frequency
greater than 20,000 cycles per second.
Ultraviolet: Electromagnetic radiation (light) with
wavelengths between the violet end of the visible spectrum and
the range characteristic of rays or radiation used to create
roentgens (x-ray images of the body).
Vaccination: The act of administering a vaccine.
Vaccine: A drug made from a killed preparation of a
specific viral or bacterial pathogen that stimulates a person's
immune system to develop specific antibodies that can recognize and prevent infection by the
organism upon subsequent exposure.
Ventilation: The process by which air (or other gases)
are moved into and out of the lungs.
Ventilator: An apparatus for administering artifical
respiration in cases of
respiratory failure. It is also know as
Vital Capacity (VC): A
function test that measures the maximum volume of air expired
from the point of maximum inspiration.
Wheezing: A raspy or whistling sound heard when
someone takes a breath in or out. It may be a
sign of airway constriction of obstruction.
Xanthoma: A papule, nodule, or plaque of a yellow
color in the skin, due to deposits of lipids. They may be an
indication of elevated levels of lipids in the blood or a
familial disorder of cholesterol metabolism.
Xenobiotic: A chemical foreign to the biological
system of an individual.
X-linked: Inheritance of a gene or genetic trait on
the X chromosome; in other words, sex-linked.
Yeast: A general term used to denote true fungi of the
family Saccharomycetaceae that are widely distributed in nature.
The term is also used to denote other single-celled, usually
rounded fungi that produce by budding.
Zoonosis: A disease of animals that may be transmitted
Zymomycetes: A subclass of phycomycetous fungi
including the orders Mucorales and Entomophythorales.