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Acute respiratory acidosis occurs when an abrupt failure of ventilation occurs. This failure in ventilation may be caused by depression of the central respiratory center by cerebral disease or drugs, inability to ventilate adequately due to neuromuscular disease (e.g., myasthenia gravis, amyotrophic lateral sclerosis, Guillain–Barré syndrome, muscular dystrophy), or airway obstruction ...
The alveolar oxygen partial pressure is lower than the atmospheric O 2 partial pressure for two reasons.. Firstly, as the air enters the lungs, it is humidified by the upper airway and thus the partial pressure of water vapour (47 mmHg) reduces the oxygen partial pressure to about 150 mmHg.
Many people with chronic obstructive pulmonary disease have a low partial pressure of oxygen in the blood and high partial pressure of carbon dioxide.Treatment with supplemental oxygen may improve their well-being; alternatively, in some this can lead to the adverse effect of elevating the carbon dioxide content in the blood (hypercapnia) to levels that may become toxic.
Hypocapnia also results in bronchoconstriction [3] in order to decrease ventilation. This mechanism is meant to counteract hyperventilation, and decrease the amount of oxygen coming into the lungs. The body's "goal" is to have a relatively even ratio of the partial pressure of oxygen to the partial pressure of carbon dioxide.
For example, a fall in arterial pO2 or an increase in arterial pCO2 (hypercapnia) leads to an increase in the rate and depth of respiration through activation of the chemoreceptor reflex. Chemoreceptor activity, however, also affects cardiovascular function either directly (by interacting with medullary vasomotor centers ) or indirectly (via ...
Drugs can greatly influence the rate of respiration. Opioids and anesthetics tend to depress ventilation, by decreasing the normal response to raised carbon dioxide levels in the arterial blood. Stimulants such as amphetamines can cause hyperventilation. Pregnancy tends to increase ventilation (lowering plasma carbon dioxide tension below ...
The V/Q ratio can therefore be defined as the ratio of the amount of air reaching the alveoli per minute to the amount of blood reaching the alveoli per minute—a ratio of volumetric flow rates. These two variables, V and Q, constitute the main determinants of the blood oxygen (O 2 ) and carbon dioxide (CO 2 ) concentration.
Hyperventilation is irregular breathing that occurs when the rate or tidal volume of breathing eliminates more carbon dioxide than the body can produce. [1] [2] [3] This leads to hypocapnia, a reduced concentration of carbon dioxide dissolved in the blood.