respiratory quotient (RQ)

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respiratory quotient (RQ)

the ratio of carbon dioxide produced to oxygen used by the whole body, or by any of its tissues, over the period of measurement. Differs according to the metabolic substrate, ranging from 0.7 for fat alone to 1 for carbohydrate alone. Overall whole-body RQ on a typical mixed diet is about 0.8. Compare respiratory exchange ratio.


pertaining to respiration. See also pulmonary.

acute respiratory disease of turkeys
see turkey coryza.
acute respiratory distress syndrome
a noncardiogenic pulmonary edema characterized by disruption of pulmonary capillary endothelium and accumulation of high-protein edema fluid in the lungs. See also shock lung, atypical interstitial pneumonia, neonatal maladjustment syndrome.
respiratory arrest
sudden complete cessation of respiratory movement.
respiratory burst of neutrophils
the series of biochemical reactions that take place within a neutrophil when a particle is phagocytosed. Important in the host defense mechanisms.
respiratory centers
see respiratory centers.
chronic respiratory disease
see chronic respiratory disease.
respiratory cilia
see cilia.
respiratory clearance
clearance of inhaled particles from the respiratory system by absorption of finally solubilized material through the respiratory epithelium, passage through the alveolar epithelium at special sites near the alveolar ducts, or to the exterior by a flow of alveolar fluid to the bronchi, a moving sheet of mucus into the bronchioles, up the bronchioles, bronchi and trachea with the assistance of repiratory cilia to the pharynx.
respiratory control
quantitative relationship between oxidative phosphorylation and electron transfer. Traditionally presented as a P/O ratio indicating the number of ATP molecules synthesized per atom of oxygen consumed.
respiratory control ratio
ratio of oxygen uptake in the presence of ADP to that in the absence of ADP. Used as an index of the functional integrity of prepared mitochondria since it is above 10 in good preparation and unity in aged or damaged mitochondria.
respiratory cycle
the cycle of inspiration, expiration, pause of the normal resting cycle depends on sensors in the respiratory system which provide stimuli to initiate the next part of the cycle.
respiratory dead space
see dead space (2).
respiratory depression
the rate and/or depth of respiration are insufficient to maintain adequate gas exchange in the lungs; a subjective judgment tending to be superseded, at least during anesthesia, by instrumentation. See respiration monitors.
respiratory depth
amplitude of each respiratory movement.
respiratory difficulty
see dyspnea.
respiratory disease pattern
may be aerogenous when the pathogen is inhaled or hematogenous when the pathogen is delivered to the lungs in the blood supply.
respiratory distress syndrome of newborn (RDS)
see hyaline membrane disease.
respiratory exchange ratio
the carbon dioxide output divided by the oxygen uptake; see also respiratory quotient (below).
respiratory failure
a life-threatening condition in which respiratory function is inadequate to maintain the body's need for oxygen supply and carbon dioxide removal while at rest; called also acute ventilatory failure. The type of failure varies with the CO2 content of the blood and may be asphyxial, when there is gasping, dyspneic when there is dyspnea, paralytic when the respiratory movements gradually fade away, tachypneic when the movements are fast and shallow.
respiratory grunting
grunting at the peak of each inspiration, or on percussion of the chest wall; indicates pain in the pleura.
respiratory insufficiency
a condition in which respiratory function is inadequate to meet the body's needs when increased physical activity places extra demands on it. Insufficiency occurs as a result of progressive degenerative changes in the alveolar structure and the capillary tissues in the pulmonary bed.
respiratory noises
includes sneezing, snorting, stridor, stertor (snoring), wheezing, roaring, grunting.
respiratory paralysis
see respiratory failure (above).
respiratory quotient (RQ)
the ratio of the volume of expired carbon dioxide to the volume of oxygen absorbed by the lungs per unit of time. Called also respiratory exchange ratio (above).
respiratory rate
the number of respirations per minute. Normal rates per minute are: horses 8 to 10; cattle 10 to 30; sheep and pigs 10 to 20; goats 25 to 35; dogs 10 to 30; cats 20 to 30.
respiratory rhythm
normally consists of three phase cycles of inspiration, expiration, pause; prolongation of inspiration suggests obstruction of the upper respiratory tract, prolongation of expiration, or a double respiratory effort suggests loss of recoil elasticity of the lungs. See also biot's respirations, cheyne-stokes respiration.
respiratory secretion
includes samples collected by nasal swab, nasopharyngeal swab, percutaneous tracheobronchial lavage and fiberoptic endoscopic sampling. Assessment is by laboratory examination for cellular content, bacteria, viruses, helminth parasites, fungi.
respiratory system
the group of specialized organs whose specific function is to provide for the transfer of oxygen from the air to the blood and of waste carbon dioxide from the blood to the air. These functions are performed by the tubular and cavernous organs which allow atmospheric air to reach the membranes across which gases are exchanged with the blood. The system includes the organs of the respiratory tract (below) plus the respiratory centers in the medulla. The supportive roles of the nervous system, the muscular, cardiovascular and hemopoietic systems are also essential.
respiratory tract
the organs of the tract include the upper respiratory tract of the nasal cavities, the pharynx, larynx, trachea and bronchi, and the lower respiratory tract comprising the bronchioles and alveoli of the lungs.
respiratory viruses
see Table 8.2.