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The abdomen
Published in Peter Kopelman, Dame Jane Dacre, Handbook of Clinical Skills, 2019
Peter Kopelman, Dame Jane Dacre
In the large bowel, most contractions are non-propulsive and serve to delay rather than promote transit. This accounts for the paradox that in diarrhoea, intraluminal pressure records show decreased activity, and in constipation increased activity. After receiving the food residues, the caecum exhibits mixing activity and then slowly contracts so that food residues reach the transverse colon over 6–10 hours. One to three times each day, mass movements occur and propel the contents into the descending and sigmoid colon. Continence is maintained by two sphincters. The internal sphincter reflects the activity of the circular muscle of the intestine; it is usually in tonic contraction. The external sphincter also shows continuous resting activity. Both the external and puborectalis muscle are inhibited on defecation and micturition.
SBA Answers and Explanations
Published in Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury, SBAs for the MRCS Part A, 2018
Vivian A. Elwell, Jonathan M. Fishman, Rajat Chowdhury
Excessive growth of the midgut results in its herniation into the umbilicus, forming the primary intestinal loop. This loop undergoes a 90-degree rotation counterclockwise. Subsequently, the midgut is rapidly retracted into the abdomen. As it does so, it rotates counterclockwise a further 180 degrees. Finally, the caecum moves inferiorly to give the definitive organization of the intestine. If the anterior abdominal wall does not close completely, loops of midgut may remain outside the abdominal cavity at birth, forming a condition known as omphalocele, or gastroschisis. Abnormal rotation of gut can cause a spectrum of anomalies; for example, there may be freely (malrotated) suspended coils of intestine that are prone to volvulus, causing constriction of its blood supply.
Introduction
Published in Shayne C. Gad, Toxicology of the Gastrointestinal Tract, 2018
Movements of the colon begin when substances pass the ileocecal sphincter. Because chyme moves through the small intestine at a fairly constant rate, the time required for a meal to pass into the colon is determined by gastric emptying time. As food passes through the ileocecal sphincter, it fills the cecum and accumulates in the ascending colon.
Cellulolytic bacteria in the large intestine of mammals
Published in Gut Microbes, 2022
Alicia Froidurot, Véronique Julliand
The large intestine of mammals (Figure 3) is a fermenter in which environmental conditions are favorable to microbial activity. It is the part of the digestive tract that follows the small intestine and begins at the cecum and includes the appendix (humans only), colon, rectum, and anus.32 The large intestine contains a minority of microorganisms that are able to degrade cellulose, including bacteria, and certain anaerobic eukaryotes (fungi and protozoa).16,33 In contrast, the abundance of microorganisms growing on soluble polysaccharides resulting from the “primary” cellulose degradation is high.16,34 In the present review, cellulolytic bacteria were focused. Despite their small quantity, cellulolytic bacteria play a crucial role, i.e., a “keystone” role, in this process, as their absence would, e.g., greatly decrease the degradation and utilization of an important substrate, thus affecting the remainder of the microbial community.33
Comparing the pharmacokinetics and organ/tissue distribution of anti-methicillin-resistant Staphylococcus aureus agents using a rat model of sepsis
Published in Xenobiotica, 2022
Shinji Kobuchi, Naoya Kanda, Taichi Okumi, Yuma Kano, Himawari Tachi, Yukako Ito, Toshiyuki Sakaeda
The rats were divided into the following two groups: normal and septic rats. Figure 1 illustrates the schedule for the preparation of the two groups and the pharmacokinetic study. Caecal ligation puncture was performed based on previously reported methods to prepare the septic rats (Ritter et al. 2003; Olguner et al. 2013). Caecal ligation puncture-induced septic rats were selected to maintain continuity with our previous pharmacokinetic studies on antibiotics (Kobuchi, Fujita, et al. 2020). Briefly, a 2-cm midline laparotomy was performed in anaesthetised rats using a mixture of medetomidine (0.375 mg/kg medetomidine, 2.0 mg/kg midazolam, and 2.5 mg/kg butorphanol). Under midline laparotomy, the caecum was ligated 1.5 cm from the end of the ileocecal valve using sutures. Multiple perforations were performed using an 18 G needle. The faeces were extruded from the perforation into the peritoneal cavity, and the caecum was returned to the peritoneal cavity. Finally, the laparotomy site was closed using a skin stapler. These rats were used as septic rats in the pharmacokinetic studies 2 h after surgery. The biochemical parameters at 0 h (2 h after surgery: the pharmacokinetic study started) and 6 h (8 h after surgery: the pharmacokinetic study ended) in normal and septic rats were measured at Kyoto Biken Laboratories Inc. (Kyoto, Japan) to investigate the time-course alterations in the pathological condition of hepatic and renal function after caecal ligation puncture.
Induction of the NEK family of kinases in the lungs of mice subjected to cecal ligation and puncture model of sepsis
Published in Tissue Barriers, 2021
Mohammad A. Uddin, Mohammad S. Akhter, Khadeja-Tul Kubra, Nektarios Barabutis
Mice were anesthetized with a subcutaneous injection of ketamine and xylazine (9:1) solution. A midline laparotomy was performed under sterile conditions. The cecum was exposed and was ligated below the ileocecal valve without disturbing the intestinal continuity. The ligated cecum was punctured twice with a 20-gauge needle. Small amount of intestinal content was extruded through the punctured holes before returning the ligated cecum to the peritoneal cavity. The abdominal and skin incision were sealed using a 3–0 silk running suture and 7 mm reflex wound clips, respectively. In the sham-operated mice, the cecum was exposed and returned to the abdominal cavity without ligation and puncture. The animals were resuscitated by subcutaneous administration of 1 ml of 0.9% NaCl solution immediately after surgery. The mice were sacrificed after 24 hours of CLP operation, and the lungs were collected and homogenized for protein analysis.