Muscular mucosae

The oviducts are also known as the Fallopian tubes or uterine tubes. The wall of the oviduct consists of three layers a mucosa, a muscular layer and an outer layer of connective tissue. When the ovum is released by the ovary, it is taken up by the oviduct. The ends of the oviducts are not directly attached to the ovaries but open into the abdominal cavity close to them. The opening of each is funnel-shaped and surrounded by long finger-like projections, fimbriae, with ciliated epithelium which catch the ovum as it is released. The other ends open directly into the uteras. The lower end of the latter is known as the cervix and opens into the vagina. 

In the human, the uterus lies like an inverted pear in the pelvis. The wall of the uterus consists of three layers a thin outer layer, the perimetrium a middle muscular layer, the myometrium and an inner glandular mucosa, the endometrium, which lines the uterine cavity. Once the ovum is fertilised, the zygote undergoes several cell cycles (Chapter 20) to form a rounded mass of cells, the blastocyst, which passes into the uterus where it implants in the wall (see below). 

Administered to mice, 49,000 ppm for 51 minutes resulted in narcosis, muscular hypotonia, disappearance of corneal reflexes, then coma followed by death. The LC50 was estimated to be 21,000 ppm in rats exposed for 3 hours. Repeated exposure of rats to concentrations ranging from 100 to 5000 ppm for 12 weeks caused a dose-related increase in irritation of the mucous membranes. At the 5000 ppm level there was marked edema or opacity of the cornea, salivation, and discharge or bleeding in the nasal mucosa. 

At the bronchi, predominantly /32-adrenoceptors are present on the smooth muscle cells. Therefor noradrenaline has hardly any influence on the muscular tonus whereas adrenaline induce a dilatation especially of precontracted bronchi, independent of the cause (histamine, acetylcholine, kinines, prostanoides). This effect can be used therapeutically in the therapy of bronchial asthma. In general the local application by aerosol is more useful than the systemic application, due to lesser side effects and the additional, beneficial effect of the reduction of mucosa swelling. 

The vagus nerve is a major connection between central and peripheral components. It contains both afferent (80%) and efferent (20%) pathways from and to the upper GIT. These include both cholinergic and non-cholinergic nerve fibres the non-cholinergic neurones may have serotonin as transmitter. Two types of vagal afferent receptors are involved in the emetic response (1) mechanoreceptors, iocated in the muscular wall of the distal stomach and proximal duodenum, which are activated by distension or contraction of the gut wall and (2) chemoreceptors located in the gut mucosa of the upper small bowel. These monitor the... 

The structure of the bladder, ureter, and urethra are similar in that they contain three layers, the mucosa, muscularis, and serosa. In the bladder (Figure 3.16) the inner layer (mucosa) when empty is infolded and it is made up of transitional epithelium. The lamina propria that is found below contains collagen and elastic fibers in the deeper layer. The muscularis is prominent and contains muscle fibers that are arranged in branching bundles separated by connective tissue. Muscular contraction causes expulsion of fluid from the bladder into the ureter. The connective tissue between the muscle fiber bundles merges with the connective tissue of the serosa. The serosa is continuous with the peritoneal lining. 

The arrangement of the major muscular component of the GI tract remains relatively constant throughout the tract, whereas the mucosa show marked variations in the different regions of the tract, reflecting the different functions of the system at different sites. Four main types of mucosa can be identified, which can be classified according to their main function ... 

Q14 Calcium gluconate and vitamin D (D3) can be used. In the presence of bile salts, oral vitamin D can be used to treat hypocalcaemia since it initiates the absorption of calcium from the diet by the intestinal mucosa. However, high levels of vitamin D can lead to calcification of the tissues, which causes severe muscular weakness and abdominal pain. 

Q5 Diverticula are sacs, or pouches, of the mucosa which form in the wall of the colon and bulge through the muscular wall of the intestine, often where arteries penetrate the intestinal wall. Their formation is associated with diets of low fibre content and is thought to be related to abnormal colon motility... 

Diverticula, which are pouches of the mucosa, can form and bulge through the muscular wall of the colon. These pouches may become infected and inflamed (diverticulitis), causing abdominal pain. Development of diverticula is associated with low-fibre diets and is thought to be related to abnormal colonic motility and high intraluminal pressures. The chance of developing diverticula increases with age. 

If atropine is administered in large amounts, it can cause a number of systemic effects, for example relaxing muscular spasm in the gastrointestinal tract, gall bladder, urinary bladder and ureter. It has been used to reverse bradycardia and dry the secretions of bronchial and oral mucosa prior to surgery. 

Mucous Surface. The mucosa of the small intestine consists of three layers (Fig. 2) an absorptive layer, a continuous single sheet of columnar epithelium the lamina propria, a layer heterogeneous in composition and cell type and the muscularis mucosa, a muscular layer separating the mucosa and submucosa. 

The movement of water molecules into and out of the alimentary canal will affect the rate of passage of small molecules across the membrane. The reasons for water flow are the differences in osmotic pressure between blood and the contents of the lumen, and differences in hydrostatic pressure between lumen and perivascular tissue, resulting, for example, from muscular contractions. It can be appreciated that the absorption of water-soluble dmgs will be increased if water flows from the lumen to the blood side across the mucosa, provided that drug and water are using the same route. Water movement is greatest within the jejunum. 

The mouth is the normal point of entry of food and drink. There, solid food is reduced in size by mastication, blended with saliva, and temperature-moderated before being swallowed. Conditions that interfere with any of these processes (e.g., tooth loss) can affect food choice and hence the nutritional status and health of the individual. The esophagus is a muscular tube through which masticated food is transported from the mouth to the stomach. It consists of both striated muscle (upper one third) and smooth muscle (lower two thirds). These muscles undergo periodic contractions in the form of peristaltic waves that push the swallowed boluses toward the stomach. The esophagus has no digestive function but secretes mucus to protect the esophageal mucosa from excoriation. 

Ulcerative colitis is confined to the rectum and colon, and affects the mucosa and the submucosa. In some instances, a short segment of terminal ileum may be inflamed this is referred to as backwash ileitis. Unlike Crohn s disease, the deeper longitudinal muscular layers, serosa, and regional lymph nodes are not usually involved. Fistulas, perforation, or obstruction are uncommon because inflammation is usually confined to the mucosa and submucosa. 

Peptic ulcer—Cellular distribution of the gastrointestinal mucosa, submucosa, and muscular layer. Chronic peptic ulcers usually occur as a single hole and are found most often in the stomach and duodenum. 

Muscular conuactiotisi ot Lite gut and secretion of acid and cn/ymes are under autonomic control. 11te enteric part of the autonomic nervous system consists of gunglionated plexuses ( ) with complex inter-connections supplying the smooih muscle, mucosa and blood vessels, fhe ganglia t > (pstrasytnpatheiic) receive extrinsic excitatory fibres from the vagus and inhibitory sympathetic fibres. Other transmitters in the gut include 5HT. Al P. nitric oxide and neuropeptide-Y. 

The normal appendix can be detected on US in more than 80% of asymptomatic patients (Rioux 1992 WiERSMA et al. 2005). It may be identified as a tubular, mobile and blind-ended structure, measuring 6 mm or less in the anteroposterior diameter (Jeffrey et al. 1988 Vignault et al. 1990). As with any intestinal bowel loop, five concentric layers that are alternately hyperechoic and hypoechoic can be identified corresponding from inner to outer hyperechoic mucosal surface, hypoechoic mucosa, hyperechoic submucosa (due to vessels, connective tissue and fat content), hypoechoic muscular, and hyperechoic serosa sometimes in smooth continuity with the hyperechoic periappendicular fat (Kimmey et al. 1989) (Fig. 1.57). The most prominent layer of the normal appendix in children is the hypoechoic mucosa due to the follicular lymphoid tissue of the mucosal lamina propria (Spear et al. 1992). 

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