Search results
Results from the WOW.Com Content Network
Though veins might make it appear as such, human blood is never naturally blue. [3] The blue appearance of surface veins is caused mostly by the scattering of blue light away from the outside of venous tissue if the vein is at 0.5 mm deep or more. Veins and arteries appear similar when skin is removed and are seen directly. [4] [5]
The tunica intima (Neo-Latin "inner coat"), or intima for short, is the innermost tunica (layer) of an artery or vein. It is made up of one layer of endothelial cells (and macrophages in areas of disturbed blood flow), [1] [2] and is supported by an internal elastic lamina. The endothelial cells are in direct contact with the blood flow.
Almost 70% of the blood in the body is in the veins, and almost 75% of this blood is in the small veins and venules. [7] All of the systemic veins are tributaries of the largest veins, the superior and inferior vena cava, which empty the oxygen-depleted blood into the right atrium of the heart. [8]
Oxygen-poor blood enters the right side of the heart through two large veins. Oxygen-rich blood from the lungs enters through the pulmonary veins on the left side of the heart into the aorta and then reaches the rest of the body. The capillaries are responsible for allowing the blood to receive oxygen through tiny air sacs in the lungs.
The pulmonary circulation is the part of the circulatory system in which oxygen-depleted blood is pumped away from the heart, via the pulmonary artery, to the lungs and returned, oxygenated, to the heart via the pulmonary vein. Oxygen-deprived blood from the superior and inferior vena cava enters the right atrium of the heart and flows through ...
The alveolar oxygen is transferred to hemoglobin, a carrier protein inside red blood cells, with an efficiency that decreases with the partial pressure of oxygen in the air. Altitude. The external partial pressure of oxygen decreases with altitude, for example in areas of high altitude or when flying.
In the blood, oxygen is bound to hemoglobin, a protein in red blood cells. The binding capacity of hemoglobin is influenced by the partial pressure of oxygen in the environment, as described by the oxygen–hemoglobin dissociation curve. A smaller amount of oxygen is transported in solution in the blood. [59]
White blood cells, carried to the area by the newly returning blood, release a host of inflammatory factors such as interleukins as well as free radicals in response to tissue damage. [2] The restored blood flow reintroduces oxygen within cells that damages cellular proteins, DNA, and the plasma membrane. Damage to the cell's membrane may in ...