Histology Mentor

Gastrointestinal System, Questions 80-94

80. Question - Make a diagram that illustrates the histology of the esophagus. Indicate the classification of the type of tissue composing each of the components.

81. Question - Diagram the histology of the full thickness of the stomach wall showing the relationship of the gastric glands to its components.

82. Question - Illustrate the histology of a fundic gland of the stomach explaining how its secretions reach the lumen of the stomach.

Secretions exit through the gastric pit.

83. Question - Illustrate the histology of a pyloric gland of the stomach explaining how its secretions reach the lumen of the stomach.

Secretions exit through the gastric pit.

84. Question - Illustrate the fine structure of the gastric chief cell. What is its function?

The chief cell secretes pepsinogen which is converted to pepsin by the stomach acid.

85. Question - Illustrate the fine structure of the parietal cell. Illustrate the fine structure of the argentaffin cell. What are their functions?

Argentaffin cells are part of the diffuse endocrine system. In the stomach, both fundic and pyloric, they produce polypeptide hormones such as gastrin. Gastrin stimulates acid secretion by the parietal cells. Parietal cells also produce intrinsic factor which is needed to absorb vitamin B12

86. Question - Illustrate the fine structure of a gastric lining cell. What is its function?

The cells that cover the surface and line the gastric pits are all mucus-secreting. In these cells the Golgi apparatus is important for the synthesis of mucus.

87. Question - What are the major differences that are seen in the transitions from the esophagus to the stomach and from the stomach to the duodenum?

At the cardiac junction (esophagus-stomach) stratified squamous non-keratinized epithelium becomes simple columnar, mucus-secreting epithelium. Submucosal and mucosal mucous glands give way to simple tubular glands emptying into short gastric pits. At first the glands are mucus-secreting but soon they become fundic glands which contain gastric chief cells, parietal cells, mucous neck cells and endocrine cells.

At the pyloric junction the simple columnar mucus-secreting epithelium gives way to a simple columnar epithelium consisting mostly of enterocytes (absorptive cells) and a few goblet cells. The mucus-secreting pyloric glands which empty into long gastric pits become large submucosal, mucus-secreting Brunner's glands which empty into intestinal glands. Villi extend above the openings of the glands.

88. Question - Diagram the histology of the small intestine identifying the differences that characterize the duodenum and the ileum.

Submucosal Brunner's glands characterize the duodenum; Peyer's patch the ileum. The plicae circulares are best developed in the jejunum.

89. Question - Diagram in detail an intestinal villus and gland naming the cells that compose these structures and identifying the villus contents.

The villus consists of lamina propria (loose irregular connective tissue) containing capillaries and lymph lacteals and capillaries. Slips of smooth muscle from the muscularis mucosae give it motility.

90. Question - Make a diagram of an enterocyte showing its relationship to neighboring cells and illustrating the absorption of fat.

Fatty acids, glycerol and mono-glycerides are absorbed from the intestine then they are reassembled into fat in the vesicles of the smooth ER. This, along with proteins from the rough ER, is brought together in vesicles which release their contents (chylomicrons) into the basolateral space by exocytosis.

91.Question - Illustrate the structure of the large intestine noting how it differs from the small intestine.

92. Question - Illustrate on a drawing three ways of viewing the functional unit of the liver - the liver lobule.

93. Question - Make a drawing showing the fine structure of adjacent liver cells and surrounding cells.

94. Question - Diagram the mucosa of the gall bladder and explain its function. Diagram the pancreatic acinus, intralobular duct and islet of Langerhans. List the cells in the pancreatic islets and their secretion products.

Alpha cells secrete glucagon which elevates blood sugar

Beta cells secrete insulin which lowers blood sugar

Delta cells secrete somatostatin which regulates secretion of alpha and beta cells

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