Question about how blood becomes oxygenated.

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This is what I came up with.

Pulmonary Artery carries deoxygenated blood into the lungs. The pulmonary artery turns into arterioles and eventually into alveoli. The blood is pushed through to that alveoli. From that specific alveoli the now oxygenated blood cell makes it's way into the left ventricle via pulmonary artery.

That obviously makes no sense.

How does the blood go from the Pulmonary Artery to being oxygenated and in the left atrium?

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Specializes in Acute Care, Rehab, Palliative.

I love this simple explanation from one of my books:

The operating principle is a process called diffusion, which causes a substance to move from a region of high concentration to a region of lower concentration. Think of a squirt of perfume diffusing from a corner in a room until you can smell it everywhere in the room.

Blood returning from the body to the lungs has a higher percentage of carbon dioxide (CO2) than the air inhaled into the lungs does. Conversely the concentration of oxygen (O2) in the inhaled air is greater than the concentration of O2 in the returning blood.

Haemoglobin, which can (loosely) bond to both O2 and CO2, facilitates the exchange of gasses from respective regions of high concentration to the regions of lower concentration. Specifically, CO2 moves from the returning blood (higher concentration) to the air in the lungs (lower concentration) and oxygen moves in the other direction, thus oxygenating the blood.When you exhale the CO2 is expelled.

The newly oxygenated blood returns via the pulmonary veins to the left atrium of the heart.

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Specializes in Neonatal Nurse Practitioner.

Remember Artery with an 'A' carries Away (from the heart).

That means blood that is returning to the heart is carried by a vein.

Here's the cycle (omitting a little bit):

system {deoxygenated blood} > veins > vena cava > right atrium > tricuspid av valve > right ventricle > pulmonary sl valve > pulmonary artery > lungs {oxygenated blood} > pulmonary vein > left atrium > mitral av valve > left ventricle > aortic sl valve > aorta > arteries > system {deoxygenated blood} ((and over & over & over & over))

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I love this simple explanation from one of my books:

The operating principle is a process called diffusion, which causes a substance to move from a region of high concentration to a region of lower concentration. Think of a squirt of perfume diffusing from a corner in a room until you can smell it everywhere in the room.

Blood returning from the body to the lungs has a higher percentage of carbon dioxide (CO2) than the air inhaled into the lungs does. Conversely the concentration of oxygen (O2) in the inhaled air is greater than the concentration of O2 in the returning blood.

Haemoglobin, which can (loosely) bond to both O2 and CO2, facilitates the exchange of gasses from respective regions of high concentration to the regions of lower concentration. Specifically, CO2 moves from the returning blood (higher concentration) to the air in the lungs (lower concentration) and oxygen moves in the other direction, thus oxygenating the blood.When you exhale the CO2 is expelled.

The newly oxygenated blood returns via the pulmonary veins to the left atrium of the heart.

great explanation, helped me too thanks!

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Diffusion takes place in the Alveoli?

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Specializes in Acute Care, Rehab, Palliative.

The alveoli are the final branching of the lungs ( not part of the pulmonary artery) The are surrounded by capillaries containing blood. The gas exchange takes place between the alveoli and the capillaries through the walls of the alveolar wall.

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Remember Artery with an 'A' carries Away (from the heart).

That means blood that is returning to the heart is carried by a vein.

That is true except in the case of the lungs. The pulmonary vein carries oxygenated blood from the lungs to the heart.

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Specializes in Emergency Department.
That is true except in the case of the lungs. The pulmonary vein carries oxygenated blood from the lungs to the heart.

Actually, the description you quoted is exactly correct. Arteries, whether or not they carry oxygenated blood, carry blood away from the heart. Veins, whether or not they carry oxygenated blood, carry blood to the heart. That is true even in the case of the pulmonary (lungs) circuit.

In the systemic (body) circuit, arteries carry oxygenated blood and veins carry deoxygenated blood. In the pulmonary (lungs) circuit, the arteries carry deoxygenated blood while the veins carry oxygenated blood.

You are correct in your description of what carries oxygenated blood in the pulmonary circuit. You just missed the direction of blood flow and which type of blood vessels carry blood in which direction, even in the pulmonary circuit.

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Specializes in Neonatal Nurse Practitioner.
That is true except in the case of the lungs. The pulmonary vein carries oxygenated blood from the lungs to the heart.

To quote myself "blood that is returning to the heart is carried by a vein." To quote you "pulmonary vein carries oxygenated blood from the lungs to the heart." We are saying the same thing.

Artery with an 'A' carries Away (from the heart). This phrase is true throughout the body. It doesn't mention the oxygenation of the blood.

The pulmonary artery with an 'A' carries blood away from the heart. So that means the pulmonary vein carries blood towards the heart.

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The way I keep the artery/vein thing straight in the heart it the saying:

PApa (Pulmonary Artery) went to the army to become a PriVate ( Pulmonary Vein)

Otherwise arteries go away from the heart with oxygen and veins come back with none.

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Actually, the description you quoted is exactly correct. Arteries, whether or not they carry oxygenated blood, carry blood away from the heart. Veins, whether or not they carry oxygenated blood, carry blood to the heart. That is true even in the case of the pulmonary (lungs) circuit.

In the systemic (body) circuit, arteries carry oxygenated blood and veins carry deoxygenated blood. In the pulmonary (lungs) circuit, the arteries carry deoxygenated blood while the veins carry oxygenated blood.

You are correct in your description of what carries oxygenated blood in the pulmonary circuit. You just missed the direction of blood flow and which type of blood vessels carry blood in which direction, even in the pulmonary circuit.

You are absolutely correct. It is easy to get things switched around expecially when you read something wrong. :) Thanks

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