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Normally, the pressure within the pleural cavity is slightly less than the atmospheric pressure, which is known as negative pressure. [1] When the pleural cavity is damaged or ruptured and the intrapleural pressure becomes greater than the atmospheric pressure, pneumothorax may ensue. Intrapleural pressure is different from intrathoracic pressure.
Local venous pressure falls to -5 at the apexes and rises to +15 mmHg at the bases, again for the erect lung. Pulmonary blood pressure is typically in the range 25–10 mmHg with a mean pressure of 15 mmHg. Regional arterial blood pressure is typically in the range 5 mmHg near the apex of the lung to 25 mmHg at the base.
Using the fact that each gram of hemoglobin can carry 1.34 mL of O2, the oxygen content of the blood (either arterial or venous) can be estimated by the following formula: = [] ( /) + PO2 is the partial pressure of oxygen and reflects the amount of oxygen gas dissolved in the blood. The term 0.0032 * P02 in the equation is very small and ...
right heart pressure is higher than left heart pressure and/or the shunt has a one-way valvular opening. Small physiological, or "normal", shunts are seen due to the return of bronchial artery blood and coronary blood through the Thebesian veins, which are deoxygenated, to the left side of the heart.
The rate of mean blood flow depends on both blood pressure and the resistance to flow presented by the blood vessels. Mean blood pressure decreases as the circulating blood moves away from the heart through arteries and capillaries due to viscous losses of energy. Mean blood pressure drops over the whole circulation, although most of the fall ...
The alveolar pressure is estimated by measuring the pressure in the airways while holding one's breath. [2] The intrapleural pressure is estimated by measuring the pressure inside a balloon placed in the esophagus. [2] Measurement of transpulmonary pressure assists in spirometry in availing for calculation of static lung compliance.
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.
Pulmonary embolism is blood clots occurring in the lungs. Restricted blood flow in the pulmonary circulation results in alveoli ventilated but not perfused, thus, increasing the V/Q ratio and decreasing gas exchange. It can cause hypoxemia(low oxygen level) and damage part of the lung, which may be treated with anticoagulants.