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Blood is not always drawn from the veins depending on the medical need and situation. For example critically ill ICU patients will often have an arterial catheter placed to provide an accurate measure of blood pressure. Blood is sometimes sampled from this line to provide a more accurate measure of blood gases and cardiac performance. But the risks of ...


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The reason why blood is red is rather simple: It is the iron atom in the middle of the heme, which plays the central part in binding oxygen. Depending on the oxidation state the blood looks either dark or light red. The structure is the following (taken from here): That the color only depends on the coordinated metal atom is shown by another related ...


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Right of the bat, veins are superficial so it is much easier to hit a vein than an artery. Arterial sticks are very difficult if you are not practiced at them while veins are much much easier. Also arterial sticks have a very specific purpose usually for example arterial blood gas. Also veins are low pressure compared to the higher pressure of arteries so ...


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Veins have several advantages over arteries. From a purely practical standpoint, veins are easier to access due to their superficial location compared to the arteries which are located deeper under the skin. They have thinner walls (much less smooth muscle surrounding them) than arteries, and have less innervation, so piercing them with a needle requires ...


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Reference values for hematocrit are identical in male and female children and as well in elderly men and women. Differences in hematocrit between fertile women and men are caused by repetitive loss of blood - and therefore iron - in menstruating women.


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Under conditions of high CO2 (in tissues such as muscle) and hence high acidity hemoglobin binds preferentially CO2, thereby mediating CO2 removal. Under conditions of low CO2 (high pH) and high O2 (conditions met in the lungs), it preferably binds O2, thereby releasing CO2. Hence, the specific characteristics of hemoglobin allow for CO2 uptake in the body, ...


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No, there is not. Cells in the bloodstream reach most areas in the body, but there are certain privileged areas which stop cells, drugs and macromolecules from leaving the bloodstream and entering the tissue. These privileged areas are thought to exist in sensitive or important areas for their own protection: Immune privilege is thought to be an ...



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