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This question falls into different subquestions: 1. How much blood does a mosquito take when feeding? This is not so easy to answer, but there are publications which measure the volume of different mosquito species. Reference 1 lists volumes between 2.85 and 11.99µL per meal and mosquito. Reference 2 lists 3.07 and 5.71µL. To make the approximation a bit ...


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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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blood clots inside the body have an unfortunate tendency to get into the bloodstream and cause blockages, leading to severe problems such as strokes or heart attacks This statement is primarily true only for blood clots within blood vessels, especially in the veins. When you are talking about bruising, you are talking about clots outside of the vasculature. ...


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@Bryan Krause's answer is quite correct. I just want to clarify what a bruise is, because I think you have a misconception of what happens. There are bruises (blood leakage into tissue because of damage to capillaries) and there are hematomas (a collection of blood in a tissue caused by breakage of either many capillaries or normally a larger blood vessel.) ...


25

Red blood cells are not equipped with a motor system to propel them through the blood stream. Instead, they are passively transported through the vasculature by the the pumping action of the heart. The effects of dangerous situations on the skin have to do with hormonal effects on the blood vasculature, and not with direct effects on red blood cells. ...


22

As you note yourself, this depends strongly on the vessel that you are studying. I found this table in reference 1: It lists speeds between 34 and 45 cm/sec for the inferior vena cava and 12 to 16 cm/sec for the superior vena cava. For the capillaries I found this table in reference 2, which measured the blood velocity in cats. Nevertheless I think this ...


16

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 ...


12

I don't know if they are classified as organs, but basically, blood vessels match the criteria for being organs. Quoting SIU School of Medicine: Blood vessels are basically tubular organs found within other organs. Biology Reference states the same: Even the glands within the integument can be considered organs; any gland is primarily secretory ...


12

I would like to add a point which I feel others have missed: our body already has a safety system to prevent such a thing from happening, called fibrinolysis. Obviously, this system is not solely for degrading clots that might have come into the bloodstream, but this is an important part of all of its functions. The main character here is plasmin: a serine ...


12

To the man with a hammer, everything looks like a nail. The poster’s hammer seems to be kidney function. Mine is the biochemistry of the erythrocyte (red blood cell). Others, no doubt will be able to provide yet different perspectives. From a biochemical point of view the erythrocyte has a limited repertoire of metabolic pathways compared with other ...


11

The blood comes from the body's reservoirs: spleen (mostly erythrocytes) [1] liver [2] veins (probably the most important blood resevoir as they contain 50-60 % of the volume) [3] In pathological situations, if hypovolemia occurs, blood can also come from: splachnic vascular bed [5] But what attracts the blood into the muscle? The phenomenon is called ...


11

The cardiovascular system is usually lumped together as an organ. So blood vessels would be included here but you are right in that this is a bit strange being that it includes the heart and the vasculature.


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From Boron and Boulpaep textbook of Medical Physiology, second edition, p.289: Because of falling ATP levels in the brain, consciousness is lost within 10 seconds of a blockade in cerebral blood flow. Irreversible nerve cell injury can occur after only 5 minutes of interrupted blood flow. If conscious is lost within 10 seconds of blockade in cerebral ...


9

Well, even though most people presume that it appears blue (reference) is due to the blood being deoxygenated, it is actually not the truth because blood is never blue whether it is deoxygenated or not. In a paper by Dr Alwin Kienle titled Why do veins appear blue? A new look at an old question, the authors measured how much light of various wavelengths was ...


9

Alternative Heart Morphologies Amphibians and some reptiles have a three-chambered heart, with 2 atria and a single ventricle. There are still separate circulatory pathways for the lungs and the rest of the body, but the oxygenated and oxygen-depleted blood mix in the ventricle, and are pushed at the same time to the lungs and body. The disadvantage of ...


9

An additional aspect is that the availability of iron usually constrains the growth of pathogens. Cassat and Skaar in "Iron in Infection and Immunity" state: Iron is an essential nutrient for both humans and pathogenic microbes.... Given the absolute requirement for iron by virtually all human pathogens, an important facet of the innate immune system is ...


8

How are diabetes and obesity connected in light of low lipase activity? Short answer: There's more than one type of diabetes. (And to complicate things, there's also more than one type of lipase. It's unclear from the question which type were mentioned in what you read.) Diabetes mellitus is usually divided into Type 1 (insulin-deficient) and Type 2 (...


8

Arterial Baroreceptors felling the pressure. Arterial blood pressure is normally regulated within a narrow range, with a mean arterial pressure typically ranging from 85 to 100 mmHg in adults. It is important to tightly control this pressure to ensure adequate blood flow to organs throughout the body. This is accomplished by negative feedback systems ...


7

How does extra blood come from to fill your muscles during exercise? Blood pumps (blood) and sucks (lymph). There are many pumps in our body thoracic pump smooth musculature respiratory pump which work together to provide the blood to the peripheral circulation. These pumps provide us Pulse, Vasomotor tone and Respiratory waves which when act together ...


7

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 ...


7

I think people can easily endure head-over-heel revolutions in space such as seen in Gravity. I am no mathematician (let alone physicist, both of whom could answer this more accurately) but here is my reasoning (faulty though it may be). You are assuming that someone would pass out from lack of blood supply to the brain. Given we have absolutely no ...


7

The key is in fluid compartments and osmotic activity. For the purposes of this discussion, let us say that there are two fluid compartments the ExtraCellular Fluid (ECF) and IntraCellular Fluid (ICF). Only the ECF contributes to blood volume and blood pressure. Na is not only the major ECF ion, but it is also confined there. The ICF concentration of Na is ...


7

Atherosclerosis can develop in high pressure systems, such as arteries, and not in low pressure systems, such as veins. It is high blood pressure that can damage the lining of the blood vessel and initiate the process of atherosclerosis. BUT, atherosclerosis can develop in veins that have been used as grafts instead of arteries, for example, in a coronary ...


6

To answer your questions, one needs to address certain issues one at a time. Veins do have valves, but they function to hold blood from settling in the legs. When you flex muscles, the blood flows towards the heart. Valve failure occurs when people stand (especially if they stand relatively still) for long periods of time every day over many years, dilating ...


6

There can be many reasons to why BBB-like barrier is not present in all the capillaries of the body. Let's talk about them one at a time. Source Blood-brain barrier has its own side effects. Some major side effects are cerebral edema (accumulation of excess water in the extracellular space of the brain, which can result when hypoxia causes the blood–brain ...


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I like it that nitrogen came to your mind ;) I guess in school they didn't tell you about the nitrogen at all, for the matter of simplification, because it is of no function in the body and the $O_{2}$ and $CO_{2}$ are the important gasses for biological function of breathing. However, all of these small gas molecules are very small and generally the ...


6

The answer to this question is quite simply this: The activation energy for the uncatalysed reaction is such that the amount of decomposition of urea in aqueous solution at blood temperature and pH is negligible in the time taken for the transfer of urea to the kidney. The literature supporting this is very old, so I shall first cite a relatively ...


6

They aren't completely rigid and can change shape to squeeze through (see Downey et al). If they are activated, monocytes can get stuck in capillaries and block them, which contributes to poor circulation following reperfusion after an ischemic blockage (see Engler et al). Downey, G. P., Doherty, D. E., Schwab 3rd, B., Elson, E. L., Henson, P. M., & ...


5

The blood type of people is determined by proteins which are anchored into the surface of the red blood cells. Cells can either express the A, B, A and B or no marker, resulting in the blood groups A, B, AB and 0. People which have a certain blood type (for example A) have antibodies against the other blood type (in this case B). This will lead to the ...


5

In the middle cerebral artery blood flow at rest is 73.7 cm/s. After a period of 3 minutes of hyperventilation, blood flow in the same artery decreases to 37.6 cm/s. This is published work. Vena cava measures: Peak velocities during ventricular systole ranged from 30 to 45 cm/sec in the inferior, and from 10 to 35 cm/sec in the superior, vena cava, also ...


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