HIST L1C | Histology of GI

Lymphatic nodules contain lymphocytes, macrophages, plasma cells, and eosinophils in the lamina propria.

SUBMUCOSA: Irregular fibroelastic connective tissue layer, with Meissner submucosal plexus controlling the motility and gland secretion.

Muscularis Externa: Inner circular smooth muscle and outer longitudinal smooth muscle layers, with interstitial cells of Cajal and Auerbach myenteric plexus.

Esophagus: Nonkeratinized stratified squamous epithelium, esophageal cardiac glands, and muscularis mucosae.

Stomach: All regions display rugae, cardia is a mucus-secreting area, and fundic mucosa has surface mucous cells and gastric pits with multiple types of cells.

Fundic Glands: Isthmus, neck, and base regions, composed of six cell types, including parietal (oxyntic), chief (zymogenic), and enteroendocrine cells, with regenerative cells and mucous neck cells.

Parietal cells produce HCl and gastric intrinsic factor, with clinical implications for vitamin B12 absorption and anemia.

Chief cells contain the proenzyme pepsinogen and secrete gastric lipase and leptin.

Enteroendocrine cells are located in the mucosa of the stomach and produce multiple hormones.

Serosa or adventitia covers the alimentary canal, depending on its location in the body.

The oral cavity has a stratified squamous epithelium and salivary glands.

The esophagus has a simple columnar epithelium below the diaphragm and undergoes a change in structure at the esophagogastric junction.

The stomach has rugae for expansion, mucus-secreting cardia, and acid-secreting pylorus.

The stomach has gastric pits that increase the surface area and contain multiple gastric glands, which are subdivided into three main regions and composed of six cell types.

Parietal cells secrete hydrochloric acid, gastric intrinsic factor, and leptin.

Chief cells contain the proenzyme pepsinogen, produce gastric lipase, and secrete ghrelin.

Enteroendocrine cells produce various hormones and neurotransmitters, including gastrin and serotonin.

Meissner submucosal plexus and Auerbach myenteric plexus control the glandular secretion and motility of the GI tract.

The muscularis externa is composed of smooth muscle, and its activity is regulated by the interstitial cells of Cajal and the autonomic nervous system.

The serosa covers intraperitoneal parts of the GI tract, and the adventitia covers retroperitoneal parts.

The oral cavity is lined by a thin non-keratinizing stratified squamous epithelium (ventral) and a thick keratinizing stratified epithelium (dorsal), and contains salivary glands and taste buds.

The esophagus has a nonkeratinized stratified squamous epithelium and contains esophageal cardiac glands, which secrete mucus and protect the esophagus from acid.

The esophagogastric junction undergoes a change in structure below the diaphragm, with a simple columnar epithelium and mucus-secreting glands similar to the cardia region of the stomach.

The stomach is lined by a mucosa with a nonkeratinized stratified squamous epithelium, and has rugae that allow for expansion and multiple gland types, including parietal, chief, and enteroendocrine cells.

The fundic glands are subdivided into three main regions: isthmus, neck, and base, and are composed of six cell types, including parietal, chief, and enteroendocrine cells, with regenerative cells and mucous neck cells.

Parietal cells secrete hydrochloric acid, gastric intrinsic factor, and leptin, and are clinically important for vitamin B12 absorption and anemia.

Chief cells contain the proenzyme pepsinogen, produce gastric lipase, and secrete ghrelin.

Enteroendocrine cells are located in the mucosa of the stomach and produce various hormones, including gastrin and serotonin.

The lamina propria contains esophageal glands, mucous cells, and serous cells, and the muscularis externa is composed of smooth muscle and is regulated by the interstitial cells of Cajal and the autonomic nervous system.

The serosa covers intraperitoneal parts of the GI tract, and the adventitia covers retroperitoneal parts.

The cardia is a mucus-secreting area of the stomach, and the fundic mucosa has surface mucous cells and gastric pits with multiple types of cells.

The pylorus of the stomach has glands that secrete mucus and produce gastrin.

The stomach has a thick, muscular wall, with multiple layers of smooth muscle and a submucosal plexus that regulates motility and secretion.

The esophagus has a simple squamous epithelium, with a lamina propria that contains esophageal glands, which secrete mucus, and a thin layer of smooth muscle.

The oral cavity has a thin, non-keratinizing stratified squamous epithelium, with taste buds, salivary glands, and sublingual folds.

The esophagogastric junction undergoes a change in structure, with a simple columnar epithelium that secretes mucus and a muscularis externa that is thinner than in the rest of the esophagus.

The stomach has a mucous membrane that lines the lumen, with surface mucous cells, gastric pits, and gastric glands that secrete hydrochloric acid and pepsin.

The mucosa of the stomach contains various cells, including parietal cells, chief cells, and enteroendocrine cells, which secrete hormones and neurotransmitters.

The gastric glands are subdivided into three regions: isthmus, neck, and base, and are composed of six cell types, including parietal, chief, and enteroendocrine cells.

Parietal cells secrete hydrochloric acid, which is important for digestion and maintains the acidic environment of the stomach, and gastric intrinsic factor, which is necessary for vitamin B12 absorption.

Chief cells contain the proenzyme pepsinogen, which is converted to pepsin and plays a role in protein digestion, and secrete gastric lipase and leptin.

Enteroendocrine cells are located in the mucosa of the stomach and secrete hormones, including gastrin, serotonin, and histamine, which regulate various digestive and metabolic processes.

The submucosal plexus, including the Meissner and Auerbach plexuses, regulates the motility and secretion of the GI tract by controlling the activity of the smooth muscle in the muscularis externa.

The serosa covers the intraperitoneal parts of the GI tract, and the adventitia covers the retroperitoneal parts.

The stomach has a thick muscular wall, with multiple layers of smooth muscle and a submucosal plexus that regulates the motility and secretion of the stomach.

The esophagus has a simple squamous epithelium, with a lamina propria that contains esophageal glands, and a thin layer of smooth muscle that regulates the peristaltic activity of the esophagus.

The oral cavity is lined by a thin, non-keratinizing stratified squamous epithelium, which is a continuous layer of cells that protects the mucosal surface and provides a barrier against the external environment.

The esophagus has a nonkeratinized stratified squamous epithelium, which is a protective layer of cells that lines the esophagus and prevents the acidic contents of the stomach from damaging the esophageal tissue.

The esophagus contains esophageal cardiac

DNES cells found in respiratory system and endocrine pancreas, their secretions identical to neurosecretions.

Stomach has three layers of muscle: oblique (innermost), circular (middle), and longitudinal (outer).

Gastric mucosa: cardiac region has no chief cells, pyloric region has mucous neck cells producing lysozyme.

Gastric pits deeper in pyloric region, entire stomach covered by serosa.

Pylorus-duodenum junction: thick smooth muscle layer (pyloric sphincter), separates stomach from duodenum.

Small intestine: 4-7 meter long, absorbs end products of digestive process, 3 parts: duodenum, jejunum, ileum.

Duodenum and jejunum: permanent folds called plicae circulares, villi and microvilli increase surface area for absorption.

Small intestine modifications: crypts of Lieberkühn, absorptive glands, increase surface area for absorption.

Epithelium of small intestine: simple columnar, enterocytes, goblet cells, DNES cells, Paneth cells.

Brunner glands: secret alkaline fluid in duodenum, neutralize acidic chyme, respond to parasympathetic stimulation.

Muscularis externa: Auerbach myenteric plexus, responsible for peristaltic activity, entire small intestine is invested by a serosa.

Duodenum, jejunum, and ileum differences: presence of Brunner glands in duodenum, villi and goblet cells vary in number and distribution, ileum has greatest development of GALT.

Large intestine: absorbs most water and ions, richly endowed with crypts of Lieberkühn, no Paneth cells, DNES cells including L cells that secrete appetite-reducing hormone peptide YY (PYY).

Large intestine: muscularis externa has taeniae coli and haustra coli, serosa displays numerous fat-filled pouches, appendices epiploicae.

Rectum and anal canal: rectum resembles colon, but crypts of Lieberkühn are deeper and fewer per unit area.