نتایج جستجو برای: gas exchange
تعداد نتایج: 422351 فیلتر نتایج به سال:
Respiration of bulky plant organs such as roots, tubers, stems, seeds, and fruit depends very much on oxygen (O2) availability and often follows a Michaelis-Menten-like response. A multiscale model is presented to calculate gas exchange in plants using the microscale geometry of the tissue, or vice versa, local concentrations in the cells from macroscopic gas concentration profiles. This approa...
Respiratory sinus arrhythmia (RSA) may be associated with improved efficiency of pulmonary gas exchange by matching ventilation to perfusion within each respiratory cycle. Respiration rate, tidal volume, minute ventilation (.VE), exhaled carbon dioxide (.VCO(2)), oxygen consumption (.VO(2)), and heart rate were measured in 10 healthy human volunteers during paced breathing to test the hypothesi...
Rising atmospheric [CO2 ], ca , is expected to affect stomatal regulation of leaf gas-exchange of woody plants, thus influencing energy fluxes as well as carbon (C), water, and nutrient cycling of forests. Researchers have proposed various strategies for stomatal regulation of leaf gas-exchange that include maintaining a constant leaf internal [CO2 ], ci , a constant drawdown in CO2 (ca - ci )...
OBJECTIVE To describe the kinetics of metabolic gas exchange at the onset and offset of low level, constant work exercise in patients with chronic heart failure. SETTING Tertiary referral centre for cardiology. PATIENTS 10 patients with chronic heart failure and 10 age matched controls. METHODS Each subject undertook maximum incremental exercise testing with metabolic gas exchange measure...
1 Ahuja A, Gothi D, Joshi J. A 52-year-old man with daytime sleepiness, sialorrhea, and facial fasciculations. Chest 2006; 130:287–290 2 Servera E, Sancho J. Appropriate management of respiratory problems is of utmost importance in the treatment of patients with amyotrophic lateral sclerosis [editorial]. Chest 2005; 127:1879–1882 3 Aboussouan LS, Khan SU, Meeker DP, et al. Effect of noninvasive...
When a subject is totally immersed in water while holding his breath, a loss of buoyancy occurs.This phenomenon can be demonstrated by resting the subject on 1 pan of a balance, the loss of buoyancy being reflected as a gain in weight on the balance. This gain in weight (or loss of buoyancy) was first observed by us while determining body density by an underwater weighing method (1). This gain ...
The paper by PEACOCK and JONES [1], "Gas Exchange at Extreme Altitude: Results from the British 40th Anniversary Expedition", presented in this issue of the Journal, reports fascinating new data recorded at extreme altitudes (up to 8,000 m) on Mount Everest. Among the interesting findings, was the fact that, on the South Col (altitude 8000 m), alveolar oxygen tension (PA,O2) (measured with a fu...
Respiratory physiological deadspace may increase from 35 per cent of the tidal volume in the normal anaesthetized, normotensive and supine patient to as much as 80 per cent in the hypotensive patient in the head-up tilt. Increased mean airway pressure, hypotension, sudden head-up tilt or maintenance of tilt, all tend to increase the respiratory deadspace. Arterial and end-tidal Pco3 differences...
The most common cause of hypoxemia at sea level is mismatched ventilation and per fusion. Common clinical problems such as pneumonia, pulmonary embolism, obstruc tive lung disease and many other diseases produce regional hypoventilation as com pared to perfusion, resulting in incompletely oxygenated blood leaving the pulmonary capillary in hypoventilated regions and re turning to the left h...
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