1. Salivary glands – These are lined by a simple cuboidal epithelium and are surrounded by myoepithelial cell bodies, and their processes typically are found along the basal surface of the duct. The important functions of the simple cuboidal epithelium are secretion and absorption.
2. Pharynx – The pharynx is composed of mucous membrane, submucosal connective tissue, glands, lymphoid tissue, muscle and an outermost adventitial coating. The pharynx chamber serves both respiratory and digestive functions. Thick fibers of muscle and connective tissue attach the pharynx to the base of the skull and surrounding structures.
3. Esophagus – The esophageal lining is protected by a stratified squamous epithelium. Because this epithelium is normally not exposed to dryness or to abrasion, it is non-keratinized.Scattered submucosal mucous glands provide lubrication. A well-developed muscularis provides peristaltic propulsion of food.
4. Stomach – The stomach and intestines have a thin simple columnar epithelial layer for secretion and absorption. The submucosa is a thick layer of loose connective tissue that surrounds the mucosa. This layer also contains blood vessels, lymphatic vessels, and nerves. Glands may be embedded in this layer.
5. Small intestine – The small intestine follows the general structure of the digestive tract in that the wall has a mucosa with simple columnar epithelium, submucosa, smooth muscle with inner circular and outer longitudinal layers, and serosa.
6. Large intestine – The four (4) layers of the large intestine from the lumen outward are the mucosa, submucosa, muscular layer, and serosa. The muscular layer is made up of two (2) layers of smooth muscle, the inner, circular layer, and the outer, longitudinal layer. These layers contribute to the motility of the large intestine.
6. Rectum – It is lined with intestinal epithelium (simple columnar epithelium) and at the anal transitional zone, it is lined non-keratinized stratified squamous epithelium. The microanatomy of the wall of the rectum is similar to the rest of the gastrointestinal tract; namely, that it possesses a mucosa with a lining of a single layer of column-shaped cells with mucous-secreting goblet cells interspersed, resting on a lamina propria, with a layer of smooth muscle called muscularis mucosa. The mucosa also makes mucus that helps stool move easily through the colon and rectum. As stool moves through the colon, more water is absorbed from it and it becomes more solid.
8. Liver – The liver has a thin capsule of dense connective tissue, and a visceral (inferior) layer of peritoneal mesothelium, and is divided into left and right lobes.The liver has very little connective tissue, which explains its softness, and susceptibility to tearing in abdominal trauma. However, a fine network of connective tissue fibers supports the hepatocytes and sinusoidal lining cells.
9. Gallbladder – The gallbladder is primarily an absorptive epithelium that functions to concentrate sodium salts of bile acids by near-isotonic fluid absorption from the gallbladder lumen.
10. Pancreas – It is lined with simple cuboidal epithelium and its important functions are secretion and absorption.The remaining tissue of the pancreas consists of endocrine cells called islets of Langerhans. These clusters of cells look like grapes and produce hormones that regulate blood sugar and regulate pancreatic secretions.
1. Salivary glands – These are lined by a simple cuboidal epithelium and are surrounded by myoepithelial cell bodies, and their processes typically are found along the basal surface of the duct. The important functions of the simple cuboidal epithelium are secretion and absorption.
2. Pharynx – The pharynx is composed of mucous membrane, submucosal connective tissue, glands, lymphoid tissue, muscle and an outermost adventitial coating. The pharynx chamber serves both respiratory and digestive functions. Thick fibers of muscle and connective tissue attach the pharynx to the base of the skull and surrounding structures.
3. Esophagus – The esophageal lining is protected by a stratified squamous epithelium. Because this epithelium is normally not exposed to dryness or to abrasion, it is non-keratinized.Scattered submucosal mucous glands provide lubrication. A well-developed muscularis provides peristaltic propulsion of food.
4. Stomach – The stomach and intestines have a thin simple columnar epithelial layer for secretion and absorption. The submucosa is a thick layer of loose connective tissue that surrounds the mucosa. This layer also contains blood vessels, lymphatic vessels, and nerves. Glands may be embedded in this layer.
5. Small intestine – The small intestine follows the general structure of the digestive tract in that the wall has a mucosa with simple columnar epithelium, submucosa, smooth muscle with inner circular and outer longitudinal layers, and serosa.
6. Large intestine – The four (4) layers of the large intestine from the lumen outward are the mucosa, submucosa, muscular layer, and serosa. The muscular layer is made up of two (2) layers of smooth muscle, the inner, circular layer, and the outer, longitudinal layer. These layers contribute to the motility of the large intestine.
6. Rectum – It is lined with intestinal epithelium (simple columnar epithelium) and at the anal transitional zone, it is lined non-keratinized stratified squamous epithelium. The microanatomy of the wall of the rectum is similar to the rest of the gastrointestinal tract; namely, that it possesses a mucosa with a lining of a single layer of column-shaped cells with mucous-secreting goblet cells interspersed, resting on a lamina propria, with a layer of smooth muscle called muscularis mucosa. The mucosa also makes mucus that helps stool move easily through the colon and rectum. As stool moves through the colon, more water is absorbed from it and it becomes more solid.
8. Liver – The liver has a thin capsule of dense connective tissue, and a visceral (inferior) layer of peritoneal mesothelium, and is divided into left and right lobes.The liver has very little connective tissue, which explains its softness, and susceptibility to tearing in abdominal trauma. However, a fine network of connective tissue fibers supports the hepatocytes and sinusoidal lining cells.
9. Gallbladder – The gallbladder is primarily an absorptive epithelium that functions to concentrate sodium salts of bile acids by near-isotonic fluid absorption from the gallbladder lumen.
10. Pancreas – It is lined with simple cuboidal epithelium and its important functions are secretion and absorption.The remaining tissue of the pancreas consists of endocrine cells called islets of Langerhans. These clusters of cells look like grapes and produce hormones that regulate blood sugar and regulate pancreatic secretions.