Defecation is a very complex process. Generally speaking, dross enters the recto-pubic abdomen and causes the urge to defecate. Liquid, gas or feces, resulting in increased pressure in the anal canal, will stimulate the junction of the rectum and anal canal – the dentate line, triggering the defecation action, similar to the pistol’s “trigger”, in English called “trigger “. At this time, the rectum and anal canal is pulled upward by the anal muscle to shorten the expansion, puborectalis muscle relaxation, so that the rectum and anal canal to form a relatively smooth arc channel, conducive to fecal discharge. At the same time, people hold their breath, abdominal pressure increases, assisting defecation. For a variety of reasons, people often have the intention to defecate but not to defecate, but try to restrain, this is the “arbitrary control of the role of stool”, at this time, the external anal sphincter in the conscious domination of the anal canal, so that the anal canal can not be dilated, the feces will retrograde to the rectum potbelly, or into the sigmoid colon. Stagnant feces will be absorbed water, become dry, resulting in difficulties in discharging. Over time, even if the feces enter the recto-pubic abdomen, the urge to defecate becomes not so strong, or even the urge to defecate disappears, and the defecation reflex cannot be induced. Moreover, restrained defecation, will make the puborectalis muscle in a state of spasm, over time, will lead to the puborectalis muscle defecation can not relax, even if you try to defecate, the rectum and anus are always kept at nearly right angles, will make the constipation more stubborn. Therefore, when you have the urge to defecate, you should try to defecate as much as possible. Holding back your bowels is an unhygienic habit that can lead to constipation. Remember: when you feel the urge, you should pass the stool!