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The control of ventilation is the physiological mechanisms involved in the control of breathing, which is the movement of air into and out of the lungs. Ventilation facilitates respiration. Respiration refers to the utilization of oxygen and balancing of carbon dioxide by the body as a whole, or by individual cells in cellular respiration. [1]
Hypoxic ventilatory response (HVR) is the increase in ventilation induced by hypoxia that allows the body to take in and transport lower concentrations of oxygen at higher rates. It is initially elevated in lowlanders who travel to high altitude, but reduces significantly over time as people acclimatize .
Exchange of gases in the lung occurs by ventilation and perfusion. [1] Ventilation refers to the in-and-out movement of air of the lungs and perfusion is the circulation of blood in the pulmonary capillaries. [1] In mammals, physiological respiration involves respiratory cycles of inhaled and exhaled breaths.
In obstructive lung disease, the FEV1 is reduced due to an obstruction of air escaping from the lungs. Thus, the FEV1/FVC ratio will be reduced. [4] More specifically, according to the National Institute for Clinical Excellence, the diagnosis of COPD is made when the FEV 1 /FVC ratio is less than 0.7 or [8] the FEV 1 is less than 75% of predicted; [9] however, other authoritative bodies have ...
AQA Education, [1] trading as AQA (formerly the Assessment and Qualifications Alliance), is an awarding body in England, Wales and Northern Ireland. It compiles specifications and holds examinations in various subjects at GCSE, AS and A Level and offers vocational qualifications. AQA is a registered charity and independent of the government.
The O grade was equivalent to a GCE Ordinary Level pass which indicated a performance equivalent to the lowest pass grade at Ordinary Level.. Over time, the validity of this system was questioned because, rather than reflecting a standard, norm referencing simply maintained a specific proportion of candidates at each grade, which in small cohorts was subject to statistical fluctuations in ...
The alveolar air pressure is therefore always close to atmospheric air pressure (about 100 kPa at sea level) at rest, with the pressure gradients because of lungs contraction and expansion cause air to move in and out of the lungs during breathing rarely exceeding 2–3 kPa. [18] [19] During exhalation, the diaphragm and intercostal muscles relax.
Minute ventilation (or respiratory minute volume or minute volume) is the volume of gas inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person's lungs per minute. It is an important parameter in respiratory medicine due to its relationship with blood carbon dioxide levels .