Wikipedia:Reference desk/Archives/Science/2014 January 13

= January 13 =

Internal bleeding results
Let's say that you have substantial internal bleeding: it's far bigger than a bruise (you have to have a transfusion in order to recover comparatively quickly), but you survive. What happens to all the blood? Does it just accumulate somewhere and gradually get absorbed? Does it somehow rot inside the body? Presumably people survived major internal bleeding in the past, before it was practical to perform surgery on this kind of thing — note that my scenario requires a transfusion for rapid recovery, not for survival — so I assume that the body has some way of dealing with it, and that it can be resolved without surgery to drain it from wherever it goes. Nyttend (talk) 05:32, 13 January 2014 (UTC)
 * Bruise doesn't seem to explain just what happens to the blood in the tissue, but as far as I know it's somehow cleaned out and broken down by the body's systems. As to whether that happens with substantial but non-lethal loss of blood internally, the internal bleeding article likewise does not seem to indicate. ←Baseball Bugs What's up, Doc? carrots→ 06:17, 13 January 2014 (UTC)
 * Didn't think to check bruise (thank you), but I came here only after reading internal bleeding, and attempting to read haemorrhage, only to find out that it's a redirect to bleeding. Nyttend (talk) 06:51, 13 January 2014 (UTC)


 * The result of internal bleeding is a hematoma -- that's not a very good article though. The mass of blood is gradually broken down and absorbed, but the process can take a long time. In any case, people usually did not survive major internal bleeding in the past. It was usually fatal. Looie496 (talk) 06:54, 13 January 2014 (UTC)
 * Thanks for the link; it appears in internal bleeding, but its presentation made me think that it was some kind of illness. I just figured that people sometimes survived substantial internal bleeding without modern medicine — "when it does not stop spontaneously" is part of the internal bleeding article, so I figured that it sometimes would stop spontaneously; and if that's possible, it might well be possible before life-threatening amounts are lost but after health- and strength-threatening amounts are lost.  Nyttend (talk) 07:02, 13 January 2014 (UTC)
 * The thing is, simple bruising usually involves capillaries, which usually heal quickly. Massive internal bleeding would suggest the severing of a major vessel. ←Baseball Bugs What's up, Doc? carrots→ 13:38, 13 January 2014 (UTC)
 * True, but I assumed that capillary bleeding wasn't likely to "compress organs and cause their dysfunction", which comes immediately before my previous quote. Nyttend (talk) 14:21, 13 January 2014 (UTC)
 * Right. It comes down to how "substantial" it is, and probably also where it is. ←Baseball Bugs What's up, Doc? carrots→ 14:48, 13 January 2014 (UTC)

What is the difference between VDRL test to treponoma test?
194.114.146.227 (talk) 08:37, 13 January 2014 (UTC)
 * According to Venereal Disease Research Laboratory test, the VDRL test is a nontreponemal test. The article Nontreponemal tests for syphilis says "Nontreponemal tests refer to a class of syphilis diagnostics that detect infection by indirect markers of infection. Nontreponemal Tests detect biomarkers that are released during cellular damage that occurs from the syphilis spirochete. In contrast treponemal tests look for antibodies that are a direct result of the infection thus, anti-treponeme IgG, IgM and to a lesser degree IgA."  Red Act (talk) 09:27, 13 January 2014 (UTC)

Hyperkalemia in case of putting surgical tourniquet strongly
What is the biochemistry process that causes hyperkalemia when the surgical tourniquet is putted on the arm (of course it's just example, but I think that it's true for every place like legs etc.) strongly.I see it in taking blood tests, especially. Thank you for the help. 194.114.146.227 (talk) 10:05, 13 January 2014 (UTC)
 * From Hyperkalemia: "Pseudohyperkalemia is a rise in the amount of potassium that occurs due to excessive leakage of potassium from cells, during or after blood is drawn. It is a laboratory artifact rather than a biological abnormality and can be misleading to caregivers. Pseudohyperkalemia is typically caused by hemolysis during venipuncture (by either excessive vacuum of the blood draw or by a collection needle that is of too fine a gauge); excessive tourniquet time or fist clenching during phlebotomy (which presumably leads to efflux of potassium from the muscle cells into the bloodstream); or by a delay in the processing of the blood specimen. It can also occur in specimens from patients with abnormally high numbers of platelets (>500,000/mm³), leukocytes (> 70 000/mm³), or erythrocytes (hematocrit > 55%). People with "leakier" cell membranes have been found, whose blood must be separated immediately to avoid pseudohyperkalemia." Red Act (talk) 16:16, 13 January 2014 (UTC)
 * First of all thank you for your comment. But still I don't understand the biochemistry process that causes hyperkalemia in case of putting surgical tourniquet strongly. Did you mean to say that when it's putted on the arm strongly, it causes to hemolysis? (and homolysis causes hyperkalemia). In addition, I understand that we are talking about hemolysis that occurs in the time of taking blood and rather than about the time after taking blood, because we both know the rule of conservation of mass that explains us which the potassium can not rise by itself after taking blood, it must be occurred in the time of the taking blood and rather than after. 5.28.147.222 (talk) 19:51, 13 January 2014 (UTC)
 * The Hyperkalemia article says that hyperkalemia is an elevated concentration of potassium "in the blood", and MedlinePlus, whose target audience appears to be non-experts, also uses that phrase. However, I think that's intentionally using sloppy wording in order to be more accessible to non-experts.  Medscape, whose target audience appears to be medical professionals, instead defines hyperkalemia in terms of potassium concentration in serum, which I presume is more accurate wording.  The Hyperkalemia section then makes sense if the concentration of potassium within blood cells is higher than in serum, so that hemolysis increases the potassium concentration in the serum.  Red Act (talk) 02:01, 14 January 2014 (UTC)

sub machine gun
what does the sub mean in sub machine gun, what's the difference between machine gun and sub machine gun? — Preceding unsigned comment added by Potholepete (talk • contribs) 21:30, 13 January 2014 (UTC)
 * The difference is in the type of ammunition - see Machine gun and Submachine gun. A submachine gun uses the same ammunition as a pistol, while a machine gun will use rifle ammunition or rounds specifically designed for the gun in question. Tevildo (talk) 22:13, 13 January 2014 (UTC)


 * In general, a submachine gun is a light, portable weapon capable of firing more than one round per pull of the trigger. THAT definition covers such weapons as the M2 carbine variant of the M1 carbine, which was never issued in a pistol chambering by the US Army, but in .30 caliber carbine, but can fire either full or semi-automatic mode, all the shorter (barrel less than 16" long) models in various chamberings of the Colt Automatic Rifle system (the XM-177 variant of which is considered a submachine gun by the US Army and by Colt, its manufacturer despite being chambered in 5.56mm NATO, a rifle round), the various variants of the Avtomat Kalashnikova, the "AK", and "machine pistols" such as the IMI "Uzi," and the MAC-10/MAC-11, Škorpion vz. 61, and Stechkin automatic pistols, which were provided with full-auto capacity to give added firepower to tank crews and special forces troops.  Troops don't have to be unusually physically strong to fire submachine guns effectively, and even quite slight women soldiers have routinely carried them.


 * In contrast, machine guns are all heavily-built fully-automatic weapons chambered either in assault rifle loadings or their own specific ammunition (such as .50 BMG) to provide sustained automatic rifle fire to infantry units or fixed positions in aircraft or tanks. Machine guns are typically neither very light nor very portable (the FN Minimi and M249 machine guns, the MG42, the Bren and the original M1918 Browning Automatic Rifle being the notable exceptions to that rule).  They generally require either a husky "squad automatic rifleman" or a pair of infantrymen to be used in an infantry unit afoot.


 * That, then, is the practical difference between a "machine gun" and a "submachine gun." loupgarous (talk) 05:37, 14 January 2014 (UTC)


 * Agree with the above, but I believe that the term was coined at the end of World War I when the ingenious Germans came up with the MP 18. At that time, the lightest Allied machine gun was the Lewis gun which was considerably heavier and required more than one man to keep it in operation. Therefore a sub-machine gun was a new class of weapon below or "sub" a full blown machine gun. The term light machine gun was already in use to describe the Lewis and similar weapons, the Vickers machine gun was described as "medium" and a "heavy" machine gun fired bigger ammunition. Hence the need for a new way of describing the German weapon. Alansplodge (talk) 08:52, 14 January 2014 (UTC)
 * The Thompson submachine gun was developed by the U.S. at the end of WWI and was apparently the first weapon called a "submachine gun" by 1919. Rmhermen (talk) 19:01, 14 January 2014 (UTC)
 * What may be of some interest is that the German term is "Maschinenpistole", literally "machine pistol". --Stephan Schulz (talk) 21:42, 14 January 2014 (UTC)