scholarly journals Control of breathing at high altitude

2012 ◽  
pp. 79-95
Keyword(s):  
High Altitude ◽  
Control Of Breathing

Control of Breathing at High Altitude

Respiration ◽  
1997 ◽  
Vol 64 (6) ◽  
pp. 407-415 ◽  
Author(s):  
Robert B. Schoene
Keyword(s):  
High Altitude ◽  
Control Of Breathing

scholarly journals Control of breathing and respiratory gas exchange in high-altitude ducks native to the Andes

2019 ◽  
Vol 222 (7) ◽  
pp. jeb198622 ◽  
Author(s):  
Catherine M. Ivy ◽  
Sabine L. Lague ◽  
Julia M. York ◽  
Beverly A. Chua ◽  
Luis Alza ◽  
...  
Keyword(s):  
Gas Exchange ◽  
High Altitude ◽  
Control Of Breathing ◽  
Respiratory Gas Exchange ◽  
The Andes

Integration of cerebrovascular CO2 reactivity and chemoreflex control of breathing: mechanisms of regulation, measurement, and interpretation

2009 ◽  
Vol 296 (5) ◽  
pp. R1473-R1495 ◽  
Author(s):  
Philip N. Ainslie ◽  
James Duffin
Keyword(s):  
High Altitude ◽  
Brain Tissue ◽  
Central Sleep Apnea ◽  
Control Of Breathing ◽  
Cerebrovascular Reactivity ◽  
Future Research ◽  
Healthy Humans ◽  
Cerebral Vasoconstriction ◽  
Cerebrovascular Co2 Reactivity ◽  
Major Factors

Cerebral blood flow (CBF) and its distribution are highly sensitive to changes in the partial pressure of arterial CO2 (PaCO2). This physiological response, termed cerebrovascular CO2 reactivity, is a vital homeostatic function that helps regulate and maintain central pH and, therefore, affects the respiratory central chemoreceptor stimulus. CBF increases with hypercapnia to wash out CO2 from brain tissue, thereby attenuating the rise in central Pco2, whereas hypocapnia causes cerebral vasoconstriction, which reduces CBF and attenuates the fall of brain tissue Pco2. Cerebrovascular reactivity and ventilatory response to PaCO2 are therefore tightly linked, so that the regulation of CBF has an important role in stabilizing breathing during fluctuating levels of chemical stimuli. Indeed, recent reports indicate that cerebrovascular responsiveness to CO2, primarily via its effects at the level of the central chemoreceptors, is an important determinant of eupneic and hypercapnic ventilatory responsiveness in otherwise healthy humans during wakefulness, sleep, and exercise and at high altitude. In particular, reductions in cerebrovascular responsiveness to CO2 that provoke an increase in the gain of the chemoreflex control of breathing may underpin breathing instability during central sleep apnea in patients with congestive heart failure and on ascent to high altitude. In this review, we summarize the major factors that regulate CBF to emphasize the integrated mechanisms, in addition to PaCO2, that control CBF. We discuss in detail the assessment and interpretation of cerebrovascular reactivity to CO2. Next, we provide a detailed update on the integration of the role of cerebrovascular CO2 reactivity and CBF in regulation of chemoreflex control of breathing in health and disease. Finally, we describe the use of a newly developed steady-state modeling approach to examine the effects of changes in CBF on the chemoreflex control of breathing and suggest avenues for future research.

Contrast of Filament Bright Rims

1994 ◽  
Vol 144 ◽  
pp. 365-367
Author(s):  
E. V. Kononovich ◽  
O. B. Smirnova ◽  
P. Heinzel ◽  
P. Kotrč
Keyword(s):  
High Altitude ◽  
Line Profile ◽  
Line Center ◽  
Magnetic Structures ◽  
The Mean

AbstractThe Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.

Clean Electron Microscope Substrate Films Used for Micrometeorite Collection and Study

1967 ◽  
Vol 25 ◽  
pp. 366-367
Author(s):  
D. M. Davies ◽  
R. Kemner ◽  
E. F. Fullam
Keyword(s):  
Thin Film ◽  
Electron Microscope ◽  
High Altitude ◽  
Amyl Acetate ◽  
Temperature Variations ◽  
Film Forming ◽  
Film Specimen ◽  
Particulate Contaminants

All serious electron microscopists at one time or another have been concerned with the cleanliness and freedom from artifacts of thin film specimen support substrates. This is particularly important where there are relatively few particles of a sample to be found for study, as in the case of micrometeorite collections. For the deposition of such celestial garbage through the use of balloons, rockets, and aircraft, the thin film substrates must have not only all the attributes necessary for use in the electron microscope, but also be able to withstand rather wide temperature variations at high altitude, vibration and shock inherent in the collection vehicle's operation and occasionally an unscheduled violent landing.Nitrocellulose has been selected as a film forming material that meets these requirements yet lends itself to a relatively simple clean-up procedure to remove particulate contaminants. A 1% nitrocellulose solution is prepared by dissolving “Parlodion” in redistilled amyl acetate from which all moisture has been removed.

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