General Structure

The two surfaces of the GI tract are referred to as the mucosa and the serosa. Although the outer surface or serosa is a thin layer of connective tissue covered with a single layer of squamous epithelial cells, the inner or mucosal surface is quite complex. The mucosa actually consists of three components (Fig. 1): a single layer of epithelial cells called the epithelium, the lamina propria, and the muscularis mucosae. Although the structure of the GI tract varies considerably from region to region, most of that variation is within the mucosa. The epithelial cells themselves are the primary source of variation and are specifically modified to carry out the functions of

FIGURE 1 The general histology of the wall of the GI tract, seen in transverse cross section.

each region of the tract. Epithelial cells may secrete fluid and electrolytes, enzymes, or mucus into the lumen or chemical messengers into the intracellular spaces. Other epithelial cells are modified specifically for the absorption of nutrients or water and electrolytes. Blood vessels and lymph nodes are found within the lamina propria, which consists primarily of connective tissue. Contractions of the muscularis mucosae change the shape of the mucosa, producing ridges and valleys that alter the absorptive or secretory area. The muscularis is two thin layers of smooth muscle oriented so that the inner layer is circular and the outer layer runs longitudinally.

The submucosa consists primarily of collagen and elastin loosely woven into a connective tissue that contains some glands and the larger blood vessels of the wall of the tract. Also within the submucosa, at its juncture with the circular muscle layer, is a network of nerves called the submucosal plexus or Meissner's plexus.

The smooth muscle responsible for motility of the GI tract is found in an inner, circular layer and an outer, longitudinal layer. The thickness of these layers varies over the different regions of the tract. In general, contractions of the circular layer narrow the diameter of the lumen, whereas contractions of the longitudinal layer shorten a particular segment of the tract. Between the circular and longitudinal muscle layers is the second nerve network, called the myenteric plexus. The myenteric plexus and the submucosal plexus are the main components of the enteric nervous system and contain numerous interconnecting cell bodies and nerve processes.

Get Rid of Gallstones Naturally

Get Rid of Gallstones Naturally

One of the main home remedies that you need to follow to prevent gallstones is a healthy lifestyle. You need to maintain a healthy body weight to prevent gallstones. The following are the best home remedies that will help you to treat and prevent gallstones.

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