Venous blood is deoxygenated blood in the circulatory system. It runs in the systemic veins from the organs to the heart. Deoxygenated blood is then pumped by the heart to lungs via the pulmonary arteries, one of the few arteries in the body that carries deoxygenated blood (the pulmonary veins likewise return the newly oxygenated blood to the heart).
Venous blood is typically warmer than arterial blood, and has a lower oxygen content and pH. It also has lower concentrations of glucose and other nutrients, and has higher concentrations of urea and other waste products. The difference in the oxygen content of the blood between the arterial blood and the venous blood is known as the arteriovenous oxygen difference.
Most medical laboratory tests are conducted on venous blood, with the exception of arterial blood gas tests. It is obtained for lab work by venipuncture (also called phlebotomy), or by fingerprick for small quantities.
Famous quotes containing the word blood:
“One memorable addition to the old mythology is due to this era,—the Christian fable. With what pains, and tears, and blood these centuries have woven this and added it to the mythology of mankind! The new Prometheus. With what miraculous consent, and patience, and persistency has this mythus been stamped on the memory of the race! It would seem as if it were in the progress of our mythology to dethrone Jehovah, and crown Christ in his stead.”
—Henry David Thoreau (1817–1862)