Colon anatomical

Many areas of the human body are colonized with bacteria— this is known as normal flora. Infections often arise from one s own normal flora (also called an endogenous infection). Endogenous infection may occur when there are alterations in the normal flora (e.g., recent antimicrobial use may allow for overgrowth of other normal flora) or disruption of host defenses (e.g., a break or entry in the skin). Knowing what organisms reside where can help to guide empirical antimicrobial therapy (Fig. 66-1). In addition, it is beneficial to know what anatomic sites are normally sterile. These include the cerebrospinal fluid, blood, and urine. 

Retroperitoneal fibrosis An accumulation of fibrotic tissues in the retroperitoneum (the anatomic space behind the abdominal cavity). Structures that lie behind the peritoneum are thus termed retroperitoneal. These structures include kidneys, the bladder, portions of the duodenum, portions of the colon, and the inferior vena cava. 

Summary of Consequences for Intestinal Microflora Failure of intestinal clearance caused by impaired motor activity or local stagnation for anatomical reasons results in Gram-negative colonization of the small bowel. Small bowel aspirate, mucosal brush, or biopsies are optional samples for culture, which is still the gold standard for detecting this type of overgrowth. 

More important possibly from the standpoint of function is the diversity of the anatomy of the pelvic colon itself. Figure 5 shows the various types of anatomical structures and the percentage occurrence of each. These percentages should be taken as indicative rather than accurate since they are based upon examination of only 210 specimens. If these percentages were accurate for the whole population of the United States, each of the least common forms (represented at the bottom of Figure 5) would exist in about 600,000 persons. It seems obvious that with this array of different types of pelvic colons (as well as transverse colons), people should differ tremendously (as they do) with respect to their problems of elimination. It is interesting to note in this connection that healthy newborn ba-... 

Absorption evaluation from luminal disappearance of drugs has been widely employed as a simple and easy method. Although the appearance of drugs in the mesenteric blood can provide a more sensitive way that enables to detect lower levels of absorption, it is technically more complicated, especially due to the colon s anatomical and morphological configuration. Another alternative for absorption evaluation is to measure drugs that appear in the systemic circulation, although this method cannot provide a direct measure of membrane permeability. 

For some drugs that, for physiological and anatomical reasons, mainly follow a passive absorption mechanism, a satisfactory colonic absorption was demonstrated. Similar absorption rates from the small and large intestine were found for oxprenolol, metoprolol, isosorbide-5-mononitrate, and glibenclamide [9], It has also been known for many years, that some lipophilic vitamins, as well as bile salts and some steroids, that undergo enterohepatic circulation show satisfactory colonic absorption [2],... 

Q6 Diverticula occur most often in the sigmoid colon this area of colon is involved in up to 90% of cases of diverticulitis. What is the anatomical position of the sigmoid colon ... 

Orally administered drugs are mainly absorbed in the small intestine (duodenum, jejunum, and ileum) and in the large intestine (colon) however, other regions, such as buccal cavity, stomach, and rectum, also can be considered potential sites for drug absorption. The various anatomical and physiological characteristics of each segment are briefly described in Table 1. 

Inflammatory bowel disease is divided into two major gastrointestinal disorders ulcerative colitis (UC) and Crohn s disease. Both diseases are chronic and tend to be characterized by periods of exacerbations and remissions. Major differences between UC and Crohn s disease are differentiated by anatomic location and distribution. UC occurs in the colon and rectum, whereas Crohn s disease can occur throughout the gastrointestinal tract. UC tends to be continuous, diffuse, and mucosal Crohn s appears segmental, focal, and transmural. Fissures, strictures, abdominal masses, and pain are commonly associated with Crohn s. Classical symptoms of UC include chronic diarrhea with tenesmus, rectal bleeding, and abdominal pain. 

Ulcerative colitis and Crohn s disease differ in two general respects anatomic sites and depth of involvement within the bowel wall. There is, however, overlap between the two conditions, with a small fraction of patients showing features of both diseases. Confusion can occur, particularly when the inflammatory process is limited to the colon. Table 34—2 compares pathologic and clinical findings of the two diseases. 

Comparison of anatomical and physiological data for the cecum and colon of ... 

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