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respiratory system

consists of the nose, pharynx, larynx, trachea, bronchi, and lungs

upper respiratory system

includes only the nose, pharynx, and associated structures

lower respiratory system

includes the larynx, trachea, bronchi, and lungs

conducting zone

consists of a series of interconnecting cavities and tubes both outside and within the lungs that function to filter, warm, and moisten air and conduct it into the lungs

respiratory zone

consists of tissues within the lungs where gas exchange occurs, including the respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli

external nose

the portion of the nose visible on the face consisting of a supporting framework of bone and hyaline cartilage covered with muscle and skin and lined by a mucous membrane

external nares

the two openings of the nose also called the nostrils

internal nose

a large cavity beyond the nasal vesitbule in the anterior skull that lies inferior to the nasal bone and superior to the mouth; lined with muscle and mucous membrane

internal nares

two openings that connect the internal nose with the pharynx; also called the choanae

nasal cavity

the space within the internal nose

nasal vestibule

the anterior portion of the nasal cavity just inside the nostrils that is surrounded by cartilage

nasal septum

a vertical partition that divides the nasal cavity into right and left sides


a groovelike passageway found on the side of the nasal cavity, formed by the nasal conchae

olfactory epithelium

a region of the membrane lining the superior nasal conchae and septum which contains recpetors for the sense of smell


a funnel-shaped tube that starts at the internal nares and extends to the cricoid cartilage of the inferior larynx; also called the throat


the superior portion of the pharynx that extends to the soft palate

soft palate

the posterior portion of the roof of the mouth; arch-shaped muscular partition between the nasopharynx and oropharynx


also called the pharyngeal tonsil; located on the posterior wall of the pharynx


the intermediate pharynx, lying posterior to the oral cavity and extending from the soft palate inferiorly to the hyoid bone


the inferior portion of the pharynx; also called the hypopharynx; extends from the hyoid bone to the opening into the esophagus and larynx


a short passageway that connects the laryngopharynx with the trachea; also called the voicebox

thyroid cartilage

two fused plates of hyaline cartilage that forms the anterior wall of the larynx; also called the Adam's apple


a large, leaf-shaped piece of elastic cartilage that is covered with epithelium; moves down and forms a lid over the glottis, the opening into the trachea


consists of a pair of vocal folds (true vocal cords) and the sapce between them (rima glottidis)

cricoid cartilage

a ring of hyaline cartilage that forms the inferior wall of the larynx

cuneiform cartilage

a pair of club- or wedge-shaped elastic cartilages anterior to the corniculate cartilages that support the vocal folds and lateral aspects of the epiglottis

ventricular folds

superior mucous membrane folds of the larynx; also called the false vocal cords

vocal folds

inferior membrane and connective tissue folds of the larynx; also called the true vocal cords


a tubular passageway for air that is anterior to the esophagus and extends from the larynx to the left and right primary bronchi; also called the windpipe

primary bronchus

a pair of branches of the trachea that lead to the right and left lung; consist of incomplete rings of cartilage and are lined by pseudostratified ciliated columnar epithelium

secondary bronchi

branches of the primary bronchi that lead to each lobe of the lung; also called lobar bronchi

tertiary bronchi

branches of the secondary bronchi that divide into bronchioles; also called segmental bronchi


branches of the tertiary bronchi that repeatedly branch into smaller terminal bronchioles

terminal bronchioles

branches of the bronchioles

bronchial tree

the extensive branching of airways from the trachea which resembles an inverted tree


paired, cone-shaped organs in the thoracic cavity that lie on either side of the heart; the primary organs of respiration

pleural membrane

double-layered serous membrane that encloses and protects each lung

parietal pleura

superficial layer of membrane that lines the wall of the thoracic cavity

visceral pleura

deep layer of membrane that covers the lungs themselves

pleural cavity

a small space between the visceral and parietal pleura which contains a small amount of lubricating fluid secreted by the membranes


inflammation of the pleural membrane that causes pain in its early stages due to friction between the parietal and visceral layers of the pleura


the broad, concave, inferior portion of the lung that fits over the convex area of the diaphragm


the narrow superior portion of the lung

costal surface

the lung surface that lies against the ribs, matching the rounded curvature of the ribs


the region of the mediastinal surface through which bronchi, pulmonary blood vessels, lymphatic vessels, and nerves enter and exit the lungs

cardiac notch

a concave space on the left lung in which the heart lies

respiratory bronchiole

branches of the terminal bronchioles that subdivide into several alveolar ducts

alveolar duct

branches of the respiratory bronchioles that lead directly to the alveoli


an air sac in the lungs lined by simple squamous epithelium and supported by a thin elastic basement membrane

type I alveolar cell

simple squamous epithelial cell that forms a nearly continuous lining of the alveolar wall; the main sites of gas exchange

type II alveolar cell

cuboidal epithelial cells that secrete alveolar fluid; also called septal cells


a complex mixture of phospholipids and proteins found in the alveolar fluid; lowers the surface tension of alveolar fluid, which reduces the tendency of alveoli to collapse

alveolar macrophages

phagocytes associated with the alveolar wall that remove fine dust particles and other debris from the alveolar spaces; also called dust cells

respiratory membrane

the combined alveolar and capillary walls where gas exchange between the air spaces in the lungs and blood takes place

alveolar wall

a layer of type I and type II alveolar cells and associated alveolar macrophages

ventilation-perfusing coupling

the phenomenon where blood flow to each area of the lungs matches the extent of airflow to alveoli in that area


the general process of gas exchange in the body

pulmonary ventilation

the inhalation and exhalation of air that involves the exchange of air between the atmosphere and the alveoli of the lungs; also called breathing

external respiration

the exchange of gases betweent he alveoli of the lungs and the blood in pulmonary capillaries across the respiratory membrane; also called pulmonary respiration

internal respiration

the exchange of gases between blood in systemic capillaries and tissue cells; also called tissue respiration


breathing in; also called inspiration

Boyle's law

states that the volume of a gas varies inversely with its pressure

intrapleural pressure

the pressure between the two pleural layers in the pleural cavity, which is always subatmospheric; also called intrathoracic pressure

alveolar pressure

the pressure inside the lungs themselves; also called intrapulmonic pressure


breathing out; also called expiration

elastic recoil

property of the chest wall and lungs that causes exhalation; their natural tendency to spring back after they have been stretched

surface tension

arises at all air-water interfaces due to the polar water molecules being more strongly attracted to each other thatn they are to the gas molecules in the air


refers to how much effort is required to stretch the lungs and chest wall


the normal pattern of quiet breathing

costal breathing

a pattern of shallow (chest) breathing due to contraction of the external intercostal muscles

diaphragmatic breathing

a pattern of deep (abdominal) breathing consisting of the outward movement of the abdomen

tidal volume

the volume of one breath

minute ventilation

the total volume of air inhaled and exhaled each minute; equal to respiratory rate multiplied by tidal volume


the apparatus commonly used to measure the volume of air exchanged during breathing and the respiratory rate


the record of air volume and respiratory rate measured by the spirometer

anatomic (respiratory) dead space

the air in airways that does not undergo respiratory exchange

alveolar ventilation rate

the volume of air per minute that actually reaches the respiratory zone

inspiratory reserve volume

the additional inhaled air taken into the lungs by taking a very deep breath

expiratory reserve volume

the extra air that is pushed out of the lungs during a forcible exhalation

residual volume

air that remains in the lungs, even after the expiratory reserve volume is exhaled; cannot be measured by spirometry

inspiratory capacity

the sum of tidal volume and inspiratory reserve volume

functional residual capacity

the sum of residual volume and expiratory reserve volume

vital capacity

the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume

total lung capacity

the sum of vital capacity and residual volume

Dalton's law

states that each gas in a mixture of gases exerts its own pressure as if no other gases were present

Henry's law

states that the quantity of a gas that will dissolve in a liquid is proportional to the partial pressure of the gas and its solubility

nitrogen narcosis

excessive amounts of dissolved nitrogen that produce giddiness and other symptoms similar to alcohol intoxication; also called the "rapture of the deep"

decompression sickness

if a scuba diver ascends too rapidly, nitrogen in the blood comes out of solution too quickly and forms gas bubbles in the tissues, causing joint pain, dizziness, shortness of breath, extreme fatigue, paralysis, and unconsciousness; also called "the bends"

deoxygenated blood

blood that is depleted of some oxygen gas

oxygenated blood

blood that is saturated with oxygen gas


the binding of oxygen and hemoglobin

percent saturation of hemoglobin

the average saturation of hemoglobin with oxygen


the tightness with which hemoglobin binds oxygen

Bohr effect

phenomenon where lower pH drives oxygen off hemoglobin, making more oxygen available for tissue cells; and elevated pH increases the affinity of hemoglobin for oxygen


hemoglobin that has bound carbon dioxide onto its alpha and beta globin chains

bicarbonate ions

how 70% of the carbon dioxide in blood plasma is transported

respiratory center

neurons in the medulla oblongata and pons of the brain that regulate the rate and depth of pulmonary ventilation

medullary rhythmicity area

the neurons of the respiratory center in the medulla oblongata that control the basic rhythm of respiration

central chemoreceptors

located in or near the medulla oblongata in the central nervous system that respond to changes in hydrogen ion (H+) concentration or P-CO2 or both, in cerebrospinal fluid

peripheral chemoreceptors

neurons located in the aortic and carotid bodies that are sensitive to changes in P-O2, H+, and P-CO2 in the blood


an increase in P-CO2 of arterial blood; also called hypercarbia


rapid and deep breathing that allows the inhalation of more oxygen gas and the exhalation of more carbon dioxide until P-CO2 and H+ are lowered to normal


the condition where arterial P-CO2 is lower than 40 mm Hg; also called hypocarbia


a deficiency of oxygen gas at the tissue level


neurons located in the walls of bronchi and bronchioles that are stretch-sensitive; also called stretch receptors


a disorder characterized by chronic airway inflammation, airway obstruction, or airway hypersensitivity to a variety of stimuli


a disorder characterized by destruction of the alveolar walls, producing abnormally large air spaces that remain filled with air during exhalation

chronic bronchitis

a disorder characterized by excessive secretion of bronchial mucus accompanied by a productive cough that lasts for three months of the year for two successive years

pulmonary edema

an abnormal accumulation of fluid in the interstitial spaces and alveoli of the lungs


an acute infection or inflammation of the alveoli


an infectious, communicable disease caused by the bacterium Mycobacterium tuberculosis that most often affects the lungs and pleurae

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