Colitis Due to Venoms
Colitis Due to Venoms Most scorpion and snake venoms contain a mixture of toxic proteins and enzymes that induce circulatory collapse, hemolysis, coagulation abnormalities, and changes in vascular resistance. All…
Changes Induced by Radiographic Substances
Changes Induced by Radiographic Substances Barium causes three types of gastrointestinal problems: (a) barium granulomas, (b) bolus obstruction, and (c) an allergic or anaphylactic reaction from the carboxymethylcellulose component of…
Histologic Features
Histologic Features The mucosa is smooth and without folds except distally in the rectum. There are no villi. The mucosal surface is flat and regular with interconnected territories containing 10…
Congenital Abnormalities
Congenital Abnormalities Cecal Agenesis Intestinal agenesis is the failure of a portion of the enteric tube to form. This disorder is rare, occurring in 1 in 50,000 pregnancies. Males are…
Lymphatic Drainage
Lymphatic Drainage The lymphatics begin as a capillary plexus that wraps around the muscularis mucosae (Fig. 13.10). This plexus sends small branches into the mucosa to reach no higher than…
Gross Features
Gross Features The large intestine is a hollow muscular organ that begins at the ileocecal valve and ends at the anus (Fig. 13.1). It includes the cecum, with the attached…
Blood Supply
Blood Supply The cecum, ascending colon, and right part of the transverse colon (midgut-derived structures) are supplied by the superior mesenteric artery via the ileocolic, right colic, and middle colic…
Innervation
Innervation Like other portions of the gut, the large bowel is innervated by the autonomic nervous system. Parasympathetic nerves stimulate colonic motor activity, whereas sympathetic nerves inhibit motility and decrease…
Embryology
Embryology The embryologic midgut gives rise to the proximal colon, including the cecum, the ascending colon, and the first two thirds of the transverse colon. The rest of the colon…
Introduction
Introduction The large intestine is divided into the appendix; the cecum; the ascending, transverse, descending, and sigmoid colon; and the rectum (Fig. 13.1). Since both the appendix and the anus…
