During the ten hours or so that food residues remain in the large intestine, part of the water in the food residues is absorbed by the large intestine mucosa. At the same time, fermentation and decay by the same bacteria in the large intestine result in the formation of feces. So what is the process of eliminating feces (Xiang in internet language) from the body? What conditions do we need to pay attention to during this process? The defecation reflex is a complex combination of low-level reflexes not governed by consciousness and high-level reflexes governed by consciousness. The defecation reflex arc includes receptors, afferent nerves, nociceptors, efferent nerves and effectors. The rectum is empty under normal conditions, but when the group movement propels feces into the rectum, such as when the volume reaches 150-200 ml and the pressure in the rectal lumen rises to 7.3 kPa, it can stimulate the receptors in the rectal wall and its nearby receptors to generate nerve impulses. The impulses are transmitted to the low-level defecation center in the lumbosacral spinal cord, and at the same time uploaded to the cerebral cortex to produce bowel movements. If the environment permits, the cerebral cortex will send an impulse to excite the defecation center and produce a defecation reflex, so that the sigmoid colon and rectum contraction, anal sphincter diastolic muscle, but also must consciously first deep inhalation, sound door closed, increase the thoracic pressure, septal muscle natural decline, while the abdominal muscle contraction, so that the increasing intra-abdominal pressure will promote the excretion of feces out of the body. Normal defecation can empty the descending colon, the splenic flexure of the colon or the upper colon, but some people cannot empty the contents of the rectum completely, and it is rare to empty all the contents of the colon. Tips [ Be careful when you have the feeling of bowel movement often!] After understanding the above defecation reflex arc, we know how the real bowel movement is generated, at this time, I need to remind you of the “false bowel movement” corresponding to the “real bowel movement”, then, what is the false bowel movement? The so-called pseudo-constipation refers to the pseudo-defecation sensation caused by external factors exerting pressure on the rectal wall, such as rectal tumors, prostate tumors, bladder stones (or childbirth head pressure) and other factors stimulating the rectum are pseudo-constipation. From the various factors listed above, it is easy to see that, unlike the real bowel movements that occur every day, pseudo bowel movements have the characteristics of recurrence and irregularity. Once such recurrent pseudo-continence (or “change in bowel habits”) occurs clinically, other diseases of the rectum or urinary tract must be investigated. Second, if the environment does not allow, the impulses from the inferior abdominal and pubic nerves will contract the external sphincter of the anal canal at will to stop the fecal discharge. The tightening force of the external sphincter is 30% to 60% greater than the internal sphincter, thus stopping the fecal discharge from the anus, which can antagonize the defecation reflex, and after a period of time, the fecal matter in the rectum returns to the sigmoid colon or descending colon, and this colonic retrograde peristalsis is a protective inhibition. Tips [ Why don’t you hold back your bowel movements too often? If you often suppress the desire to defecate, the rectum will gradually lose its sensitivity to the pressure stimulation of feces and lose its sense of defecation, plus the feces stays too long in the large intestine, the water is absorbed excessively and becomes dry and hard, resulting in difficulty in defecation, which is one of the causes of constipation. [Why is it a good habit to have a bowel movement after waking up and after meals? When people get up in the morning, the rise reflex and the gastrocolic reflex after breakfast can promote the peristalsis of the colon group and produce the defecation reflex. Therefore, regular defecation in the morning or after breakfast meets the physiological requirements, which is of great significance for the prevention of anorectal disorders. The number of bowel movements and habits vary from person to person, generally once a day, after breakfast defecation. Some people have a bowel movement once in 1-2 days, but do not feel the difficulty of defecation. Therefore, constipation, diarrhea or change in the regularity of defecation cannot be determined by the number of bowel movements, but should be determined by reference to each person’s defecation habits. Four words to summarize this article: 1, the bowel reflex is quite complicated; 2, false bowel movements should be closely investigated; 3, bad habit of holding back stool without defecation; 4, regular defecation is of great significance!