What is the difference between the esophagus and the stomach

As food travels through the digestive system it is broken down, sorted, and reprocessed before being circulated around the body to nourish and replace cells and supply energy to our muscles. Digestion starts in the mouth where chewing and saliva breaks down food so it is more easily processed by your body. Esophagus: The esophagus is a muscular tube that connects the pharynx throat to the stomach. The esophagus contracts as it moves food into the stomach. This valve opens to let food pass into the stomach from the esophagus and it prevents food from moving back up into the esophagus from the stomach.

Stomach: An organ with strong muscular walls, the stomach holds the food and mixes it with acid and enzymes that continue to break the food down into a liquid or paste. Small Intestine Small Bowel : Almost 20 feet long, the small intestine is the workhorse of the digestive system. It will continue to break down food with enzymes released by the pancreas and bile released from the liver.

It is made up of three segments, the duodenum, which continues the breakdown of food; and the jejunum and ileum, which are mainly responsible for the absorption of nutrients.

Below the diaphragm, however, the esophagus is suspended within abdominal cavity and is therefore covered by a connective tissue serosa as shown in slide General Characteristics: The stomach is divided into four regions: the cardia, fundus, corpus body and pylorus. The wall of the stomach consists of the usual four layers present in other parts of the gastrointestinal tract.

The mucosa is relatively thick and contains numerous tubular glands. The muscularis mucosae is also thick and, in some areas, it consists of 3 layers of smooth muscle, although this layering is not always visible.

Glands are absent in the submucosa. In the empty contracted stomach, the mucosa is thrown into longitudinal folds rugae because of the contraction of the muscularis mucosae and the loose consistency of the submucosa. The surface is further subdivided by furrows, the gastric pits.

These funnel-shaped invaginations of the epithelium are continuous at their base with the tubular glands. The muscularis externa is made up of 3 ill-defined layers. On the basis of differences in the types of glands present in the mucosa, three histological regions can be distinguished in the stomach. The first region around the cardia contains the cardiac glands. The second region, which includes the fundus and corpus, contains the gastric glands proper also called fundic glands.

The distal region of the stomach pylorus contains pyloric glands. Cardiac glands W pg , These mucosal glands are composed mainly of mucous cells with pale staining cytoplasm and basally located nuclei. Present, but not seen, are stem cells and endocrine cells. In slide , locate the cardio-esophageal junction W pg , Note the abrupt transition from the mucosa of the esophagus with its stratified squamous epithelium to the glandular mucosa of the stomach.

The cardiac gastric glands View Image are present only in a very small segment of the stomach mucosa adjacent to this junction. Since the cardiac gastric glands are primarily mucous, they can also be be demonstrated with the PAS stain, as shown in slide In this slide, the cells lining the gastric pits View Image stain very intensely with PAS due to the carbohydrate-rich, viscous mucus they secrete. The secretion of the cardiac glands is a bit more watery so they do not stain quite as intensely.

Gastric glands W pg , At low magnification, notice that the gastric pits are relatively more shallow here View Image and the tubular gastric or fundic glands are relatively much longer than those in the cardia or pylorus.

Observe that the tall columnar cells lining the luminal surface and pits have basally located nuclei and lightly staining cytoplasm. Most of these cells secrete mucus, that is stored in the apical cytoplasm.

You can see these cells in the stomach preparation stained with PAS which will stain mucus and other glycoproteins in slide In this slide, the mucous cells of the gastic pits stain quite intensely. Also identifiable are lighter-staining "mucous neck cells" present in the neck region of the gastric glands and mucus-secreting cells of the cardiac glands found near the gastro-espophageal junction.

Parietal cells are large, ovoid to pyramidal shaped cells with their broad side adjacent to the basement membrane. Each cell contains a round, centrally located nucleus and reveals a lightly eosinophilic cytoplasm that appears granular due to the presence of many mitochondria.

The chief cells are present in the lower one-third to one-half of the gastric glands. However, in other preparations slides and , the pepsinogen has been extracted and the empty secretory granules resemble many glass beads in the supranuclear cytoplasm. The base of the cytoplasm, on the other hand, is distinctly basophilic. Other cells of the gastric glands, such as undifferentiated stem cells and various endocrine cells, will NOT be studied in this laboratory session as they are not readily identifiable in the stomach, but you should be aware of their general characteristics.

Notice the presence of a large number of lymphocytes and plasma cells in the lamina propria between the gastric glands, and, in some areas, aggregated as lymphoid nodules View Image which will be studied in greater detail along with other lymphatic tissues but you should at least be able to identify them here. Also, notice that the strands of smooth muscle fibers from the inner layer of the muscularis mucosae extend between the glands toward the surface. The contraction of these strands may help the emptying of the glands.

Pyloric glands W pgs , In slide , you can see the transition from pylorus of the stomach to duodenum of the small intestine.

The pyloric region of the stomach is characterized by a thick wall due to the presence of the pyloric sphincter muscle View Image , which is comprised primarily of the inner circular layer of the muscularis externa. The esophageal sphincters normally prevent the contents of the stomach from flowing back into the esophagus or throat.

As a person swallows, food moves from the mouth to the throat, also called the pharynx 1. The upper esophageal sphincter opens 2 so that food can enter the esophagus, where waves of muscular contractions, called peristalsis, propel the food downward 3. The food then passes through the lower esophageal sphincter 4 and moves into the stomach 5.

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