As you can see, the needles in the picture are from thin to thick, don’t let the liver tremble, not all needles are used to beat people, listen to me one by one~
First of all, it must be clear that the diameter of the needle is directly proportional to the capacity of the syringe, that is, the larger the syringe, the larger the needle. For example, the needle of a 50 ml syringe is the second (I think) pink one on the right side of the picture. , Especially thick.
In order to give everyone an intuitive feeling, I took two shots specially.
Feel it? ~~ The upper one is the needle of a 50 ml syringe, and the lower one is the needle of a 2 ml syringe.
There are two standards for needle specifications. One is the international standard, which is represented by the number +G. The larger the number, the thinner the needle.
One is the Chinese standard, which is represented by a certain number. The larger the number, the thicker the needle. (Previously it was a typo! Thanks for the correction!)
It’s really annoying to have two sets of different standards for one needle.
So the specification of the big needle above should be 20G, 8 gauge needle
The size of the small needle below should be 23G, 6 gauge needle.
Xiao Jiujiu of the needle comes to an end, and then the injection
Clinical injections are simply divided into four types: intradermal injection, subcutaneous injection, intramuscular injection and intravenous injection
In addition to these injections, needles are also used for blood collection and puncture.
In the description of the subject, the concept of "meat" should be three kinds of injections besides intravenous.
Among the three types of injections, the intradermal injection uses a small needle with a diameter of only 0.45mm, so the diameter of the hollow tube in the middle is even smaller.
0.45-0.5 needles are used for subcutaneous injection
For intramuscular injection, a 0.6-0.7 needle is used.
It is worth noting that clinically, in order to alleviate the pain of patients, small needles are used as much as possible. Therefore, it is very common to use 0.5mm needles when muscles are punched. As for the scary needles of the 50 ml syringe, they are generally used. It's used to draw fluids, it won't be used to beat people at all, so don't worry.
It can be seen that it is impossible to use a very thick needle for infusion and tonic.
When the bevel of the needle penetrates the skin, well, give a schematic diagram
You can think of the needle penetration as puncturing jelly. In fact, the skin is pierced into a gap, and the jelly is automatically backfilled when the needle is pulled out. This analogy is not very appropriate. The subject can look at other answers to complement each other. Some explanations are more accurate than mine.
In addition, the needle is in the blood only during intravenous injection or venipuncture. Due to the pressure difference, there will be "blood back" when the liquid is not injected, which means that there will be red blood at the needle plug of the syringe close to the needle. This is an important sign to check whether the needle enters the blood vessel correctly. .
At this time, we can say that there is blood in the diameter of the needle when the medicine is not applied. This phenomenon is caused by the pressure difference and the physical properties of the liquid, which is easy to change. The physical principles please explain to the physics gods. = = That barren physics knowledge in high school can only be explained here. You understand. . . .
Therefore, we can only say that when "meat" is used, that is, intradermal, subcutaneous, and intramuscular injection sites, they are all solid. Even if I compare jelly, that doesn’t change whether they are solid or semi-solid red fruit. fact! When the needle is inserted, there is a pressure difference, but because the diameter of the needle is extremely small, the tissue is elastic, and the internal and external pressure difference is not large enough, it is impossible for meat to be blocked in the diameter of the needle, otherwise how to inject the medicine Liquid ==.
If you take a tube as thick as your thumb, there will be meat stuck in it, because the space that the tissue can leave is limited. . . . .
So, is there a needle that can keep the meat in the needle?
This is called a biopsy needle, the needle is big enough, roar! ~ This needle is used for pyramidal tumors and unknown
Biopsy sampling, cell aspiration, etc. of tumors, etc. It must be noted that this needle has negative pressure, which is the large white device on the picture. That is to say, after the needle is inserted, a certain pressure must be applied to remove the "meat", that is, solid or The semi-solid tissue is sucked into the needle. And there are several shapes of biopsy needles, not all bevels, because other shapes are more conducive to grabbing out the tissue, beveled needles are used to cut a small gap and then pass the needle through the gap.
So you see, different needle shapes determine the purpose. This shape of the bevel needle can avoid the retention of fine tissues during puncture.
Therefore, the kind of needles that we usually use for injections, not to mention the small needles, and there is no negative pressure device, and it is impossible to suck meat~=￣ω￣=
Summary: When injecting or drawing blood, due to the role of the needle tip obliquely facing the skin and the elasticity of the skin tissue, the internal and external pressure difference is not enough to squeeze the tissue into the needle tube. There will be no "flesh" left in the needle tube~
Many people in the comments mentioned bone puncture, which is a type of biopsy needle.
However, because the bone is worn and the bone marrow fluid is pumped, the needle is thick and hard, and no negative pressure device is required.
There are three types of bone piercing: piercing the iliac crest (around the protrusion that can be touched by the pelvis, and a moment of silence for the intangible)
Piercing the spine
Piercing the sternum
In order to take care of everyone’s feelings, I specially selected a small needle
Some people also mentioned that the hypodermic needle of insulin is thinner than the data I listed above.
In this special science, the subcutaneous injection of insulin is very special, mainly on the stomach, and the injection is vertical.
The characteristic of this injection is to pinch the skin and hit vertically.
This injection needle is the smallest and smallest needle I have seen. How small is it?
It is smaller than the 0.45mm (27G) intradermal injection needle mentioned above. It can be as small as 29G and above 30G.
In addition, in addition to insulin, there are also some anticoagulants that are used in this way, with the same small needles.
