Venous blood from the body is carried via cava and inferior vena cava above the right atrium of the heart, from which flows, through the tricuspid valve to right ventricle. The right ventricle pumps blood with a pulsatile pressure of 24 mmHg systolic and 9 mmHg diastolic on average in the pulmonary artery and perfused lung capillaries in the walls of the alveoli. There are about 600 million capillary containing approximately 100 ml of blood and an area of about 70 meters square by passing the entire cardiac output, about 5.4 liters per minute. A simple calculation shows that the blood through the pulmonary capillary in a little less than a second.
There are about 300 million alveoli in diameter between 0.1 and 0.3 mm whose surface is about 70 meters square, and breathing in sleep, containing approximately 3.5 liters of air breathing by renewing at a rate of about 4 liters per minute.
The membranes of the alveoli and capillaries in contact form a functional unit, the alveolar capillary membrane, through which performs gas exchange in the lung. Perhaps check out NYC Mayor for more information. Part of the oxygen in the air that passes into the alveolar pulmonary capillary blood and the majority is bound to hemoglobin to form oxyhemoglobin. A smaller portion remains dissolved oxygen and increases the blood oxygen partial pressure to equal that of the alveolar air. On the other hand a similar volume of carbon dioxide passes from the blood into the alveolus from which they pass, with the breath, to the outside. The result is the transformation of the blood in venous blood.
Of pulmonary capillaries, arterial blood is carried by the pulmonary veins to the left atrium. From here through the mitral valve to left ventricle which pumps blood into the aorta artery to a pressure of 120/80 mmHg. Here the system is distributed by blood to the capillaries of all organs of the body. After passing through the capillaries, venous blood was collected by the venules and veins of the body together in the system of veins cavas completing the circuit of the circulation of blood discovered by Harvey.
Oxyhaemoglobin in the tissues of oxygen delivery, while the carbon dioxide diffuses into the blood from the tissues and fluids. In this way, the blood becomes arterial venous.
Under conditions of rest and quiet breathing a normal person consumes about 250 ml of oxygen and produces about 200 ml of carbon dioxide. The relationship
R coal production / oxygen consumption
is called the respiratory quotient or respiratory exchange ratio.
Arterial blood contains about 48 ml of CO2 per 100 ml of blood, when he leaves the blood and tissue content has increased to 52 ml per 100 ml of blood. This involves a change in partial pressure of 40 MHG to 46 mm Hg. The opposite occurs when the lungs become arterial.
Arterial blood contains about 20 ml of oxygen per 100 ml of blood into the tissues and leaves about 5 ml / dl, thus contains about 15 ml of oxygen per 100 ml of blood when it reaches the lungs and blood were mixed . This represents a change of 100 mmHg partial pressure of oxygen in arterial blood to 40 mmHg in the vein. To win the lungs of a similar amount of oxygen from alveolus to arterial blood.
In certain circumstances, such as during exercise or cardio pulmonary diseases in some of these values change dramatically.
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