Since birth, there are some intestinal bacteria that have made the intestines their home and continue to do so, such as bacteria like bifidobacterial, H. pylori, lactobacilli, and E. coli. Most of the bacteria found in the human body are found in the gut (Cao et al., 2020). The body of a human being is more than just a collection of intricately coordinated moving parts, it is viewed as a machine. The biggest change in human perception of health and sickness, nevertheless, was brought about by the discovery of microorganisms. Doctors and researchers discovered that although some microbes were to blame for human illnesses, others were abundant in human systems even when healthy.
These intestinal bacteria are of physiological significance; a microbiota, whose elements are metabolically varied and generally sophisticated, is found in the large intestine of humans. Its main job is to recover energy from carbohydrates that are not fully absorbed in the small intestines. “This is accomplished by the fermentation and absorption of short-chain fatty acids (SCFA), which account for 40–50% of the carbohydrate’s usable energy” (Cummings and Macfarlane, 2018, p.32). Additionally, xenobiotics, bile acids, and various sterols are all metabolized by intestinal bacteria, as well as vitamins K and B. Intestinal bacteria are also related to people’s likelihood of losing or gaining weight. The bacteria in other people take more energy out of the same diet. The microbiome’s activities are also associated with the hormones responsible for making people feel full.
Defecation is regulated by the nervous system, which communicates with the spinal cord and the brain. “The muscle fibers of the bowels are controlled by the enteric nerve system, while the anus and rectum muscles are controlled by the autonomic system” Heitmann et al., 2021, p.7). The autonomic nervous system provides information to the brain about the condition of the bowels, and the latter then gets directives from the central nervous system to govern the digestive tract’ muscles. The digestive tract sends signals to the brain telling it when the intestines are full (Benarroch, 2020). The muscle fibers in the anus and rectum are then instructed by the central nervous system to constrict and force the excrement out.
References
Benarroch, E. E. (2020). Physiology and pathophysiology of the autonomic nervous system. CONTINUUM: Lifelong Learning in Neurology, 26(1), 12–24. Web.
Cao, Y., Liu, H., Qin, N., Ren, X., Zhu, B., & Xia, X. (2020). Impact of food additives on the composition and function of gut microbiota: A review. Trends in Food Science & Technology, 99, 295–310. Web.
Cummings, J. H., & Macfarlane, G. T. (2018). Role of intestinal bacteria in nutrient metabolism. Clinical Nutrition, 16(1), 3–11.
Heitmann, P.T. et al. (2021) “Understanding the physiology of human defaecation and disorders of continence and evacuation,” Nature Reviews Gastroenterology & Hepatology, 18(11), pp. 751–769. Web.