p.2
Histological Layers of the Gastrointestinal Tract
What is the role of the muscularis mucosae?
It controls the shape of the mucosa and the movement of the villi in the small intestine.
p.13
Special Features of the Duodenum
What structures are present in the duodenum that aid in absorption?
Intestinal villi with numerous goblet cells.
p.17
Histology of the Large Intestine
How do the lengths of the taenia coli compare to the large intestine?
The lengths of the taenia coli are shorter than the length of the large intestine, resulting in a circular appearance.
p.17
Histological Layers of the Gastrointestinal Tract
Are villi present in the large intestine?
No, there are no villi in the large intestine.
p.15
Cell Types in Gastric Glands
How does TNF-alpha contribute to the function of Paneth cells?
It supports the inflammatory response.
p.5
Histology of the Esophagus
What stimulates the striated muscle in the esophagus?
The swallow reflex when food is pushed by the tongue towards the pharynx.
p.11
Functions of the Gastrointestinal Tract
What role do pancreatic secretions play in the small intestine?
They enter the duodenum to aid in digestion.
p.11
Histology of the Small Intestine
What is the function of the crypts of Lieberkuhn?
Involved in the secretion of enzymes and other materials.
p.7
Histological Layers of the Stomach
What covers the external surface of the stomach?
A smooth layer of serosa made up of mesothelial cells and supporting connective tissue.
p.9
Cell Types in Gastric Glands
What do the granules in Chief Cells contain?
Inactive forms of digestive enzymes (zymogens) like pepsinogen.
p.2
Histological Layers of the Gastrointestinal Tract
What are the three components of the mucosa?
Epithelium, lamina propria, and muscularis mucosae.
p.16
Peyer’s Patches in the Ileum
What are Peyer’s Patches?
Aggregations of activated lymphocytes in the ileum.
p.13
Cell Types in Gastric Glands
Where are goblet cells located in the duodenum?
Among the absorptive columnar epithelial cells.
p.14
Cell Types in Gastric Glands
What is the role of Paneth cells in the intestinal glands?
Protective and defense functions.
p.15
Cell Types in Gastric Glands
What role do defensins play in the function of Paneth cells?
They increase the permeability of bacterial membranes.
p.14
Cell Types in Gastric Glands
How do Paneth cells support stem cells?
By supporting their development.
p.1
Histological Layers of the Gastrointestinal Tract
How do the histological features of the GI tract vary?
They vary significantly along the tract, related to the different functions of each part.
p.11
Histology of the Small Intestine
What are the three parts of the small intestine?
Duodenum, jejunum, and ileum.
p.8
Histology of the Stomach
Where do the straight tubular fundic glands open?
Into the bases of gastric pits.
p.9
Cell Types in Gastric Glands
What protects Chief Cells from the digestive activity of pepsin?
The enzymes are activated only in the acidic environment of the stomach after secretion.
p.6
Histology of the Stomach
What are the four anatomical parts of the stomach?
Cardia, fundus, body, and pylorus.
p.2
Histological Layers of the Gastrointestinal Tract
What does the submucosal plexus regulate?
The secretion of the gastric glands and the motility of muscularis mucosae.
p.15
Cell Types in Gastric Glands
What antibacterial substances are produced by Paneth cells?
Lysozyme, defensins, and TNF-alpha.
p.13
Functions of the Gastrointestinal Tract
What enzymes are present at the microvilli?
Disaccharidases and peptidases.
p.5
Histology of the Esophagus
What role does the striated muscle in the upper end of the esophagus play?
It contributes to the upper esophageal sphincter, controlling the entry of food into the esophagus.
p.8
Histology of the Stomach
What type of epithelium lines the surface of the stomach?
Simple columnar epithelium.
p.7
Histology of the Stomach
What are gastric pits?
Holes that lead to gastric glands at the bases.
p.17
Functions of the Gastrointestinal Tract
What is the primary function of the large intestine?
Mainly involved in the absorption of water, electrolytes, and Vitamin K.
p.15
Cell Types in Gastric Glands
What type of granules do Paneth cells contain?
Large eosinophilic (acidophilic) granules.
p.14
Cell Types in Gastric Glands
Where are undifferentiated stem cells located in the intestinal glands?
At the base of the glands.
p.17
Histology of the Large Intestine
What can be observed in the mucosa of the large intestine?
The lumens of intestinal glands and the muscularis mucosae.
p.10
Cell Types in Gastric Glands
Which cells are most abundant in the fundus and body of the stomach?
Parietal and chief cells.
p.5
Histology of the Esophagus
What is the function of the secretion from the submucosal glands in the esophagus?
To provide lubrication to the surface of the esophagus.
p.12
Special Features of the Duodenum
What are Brunner’s glands?
Submucosal glands in the duodenum that secrete alkaline mucus.
p.3
Histological Layers of the Gastrointestinal Tract
Where are most glands located in the digestive tract?
In the mucosa, except in the esophagus and duodenum where they are in the submucosal layer.
p.7
Histological Layers of the Stomach
What is the role of the muscularis externa in the stomach?
It consists of three muscle layers that increase the strength of mixing and digesting food.
p.9
Cell Types in Gastric Glands
What is the function of intrinsic factors secreted by Parietal Cells?
To complex with Vitamin B12 in the ileum for absorption.
p.9
Cell Types in Gastric Glands
What is the current term for the system that includes EC Cells?
Diffuse neuroendocrine system (DNES).
p.2
Histological Layers of the Gastrointestinal Tract
What is the submucosa made of?
A thick connective tissue layer.
p.1
Functions of the Gastrointestinal Tract
What is the function of the Muscularis Externa?
Responsible for segmental movement and peristalsis in the GI tract.
p.1
Histological Layers of the Gastrointestinal Tract
What does the Submucosa layer contain?
A thick layer of connective tissue that supports the mucosa.
p.6
Histology of the Stomach
How does the histology of the fundus compare to the body of the stomach?
Histologically and functionally, they are the same.
p.15
Cell Types in Gastric Glands
What recent role have Paneth cells been shown to play?
An important part in stem cell development in the small intestine.
p.3
Histological Layers of the Gastrointestinal Tract
What is the composition of the serosa?
Mesothelium (simple squamous epithelium) and a thin layer of connective tissue.
p.11
Histology of the Small Intestine
What is unique about the epithelium of the small intestine?
It is the only region in the GI tract where villi are present.
p.9
Cell Types in Gastric Glands
What receptors regulate secretion in Parietal Cells?
Receptors for gastrin, histamine H2, and acetylcholine M3.
p.15
Cell Types in Gastric Glands
Where are Paneth cells primarily located?
In the small intestine, with lower density in the cecum and appendix.
p.6
Histology of the Stomach
What is a key feature of the fundus during X-ray examination?
It appears as a dark shadow because it is commonly filled with air.
p.17
Histology of the Large Intestine
What is the role of intestinal glands (crypts) in the large intestine?
They are present for absorption and secretion.
p.17
Goblet Cells in the Gastrointestinal Tract
What is unique about the density of goblet cells in the large intestine?
The large intestine has the highest density of goblet cells along the entire GI tract.
p.6
Histology of the Stomach
What is the function of the pyloric sphincter?
It acts as a strong circular muscle ring controlling the opening to the duodenum.
p.13
Cell Types in Gastric Glands
What are microvilli and where are they found?
Microvilli are projections on the apical surface of columnar epithelial cells that increase absorptive area.
p.1
Histological Layers of the Gastrointestinal Tract
What is the serosa?
A smooth membranous layer covering most parts of the GI tract.
p.3
Histological Layers of the Gastrointestinal Tract
What additional muscle layer is present in the stomach's muscularis externa?
An innermost oblique muscle layer.
p.1
Histological Layers of the Gastrointestinal Tract
Why is the serosa absent in the esophagus?
Because the esophagus is located in the mediastinum, surrounded by connective tissue.
p.3
Functions of the Gastrointestinal Tract
What is the myenteric plexus?
A network formed by the synapse of parasympathetic fibers in the muscularis externa.
p.5
Histology of the Esophagus
What is present instead of serosa in the esophagus?
Adventitia, which is connective tissue.
p.11
Histology of the Small Intestine
What special adaptations does the small intestine have for absorption?
Villi that increase the surface area.
p.7
Histological Layers of the Stomach
What are the layers of the stomach from the luminal side?
Rugae, mucosa, submucosa, muscularis externa, and serosa.
p.8
Cell Types in Gastric Glands
What are enteroendocrine cells?
Hormone-secreting cells distributed along the GI tract.
p.4
Histology of the Esophagus
What type of epithelium makes up the mucosa of the esophagus?
Non-keratinized stratified squamous epithelium.
p.17
Histology of the Large Intestine
What type of cells line the epithelium of the large intestine?
Columnar epithelial cells.
p.2
Histological Layers of the Gastrointestinal Tract
How can the submucosal plexus be visualized?
By silver staining, which reveals the nerve fibers and cell bodies.
p.15
Cell Types in Gastric Glands
What is the function of lysozyme produced by Paneth cells?
To degrade bacterial walls.
p.5
Histology of the Esophagus
What type of epithelium is found in the esophagus?
Stratified squamous epithelium, non-keratinized.
p.4
Histology of the Esophagus
Why is the smooth serosa absent in the esophagus?
Because the esophagus is located in the mediastinum and is filled with connective tissue.
p.1
Histological Layers of the Gastrointestinal Tract
What is the layer surrounding the esophagus called?
Adventitia, composed of connective tissue.
p.13
Cell Types in Gastric Glands
How does the number of goblet cells change from the duodenum to the ileum?
The number of goblet cells increases.
p.10
Cell Types in Gastric Glands
How are the gastric pits in the pylorus described?
The longest gastric pits.
p.11
Functions of the Gastrointestinal Tract
What are the main functions of the small intestine?
Digestion, absorption, and secretion of hormones.
p.8
Histology of the Stomach
What are the two distinct regions of the fundic gland?
The neck region and the base region.
p.9
Cell Types in Gastric Glands
What were EC Cells formerly referred to as?
APUD (amine precursor uptake & decarboxylation) cells.
p.1
Histological Layers of the Gastrointestinal Tract
What are the four distinct histological layers of the gastrointestinal tract?
Mucosa, Submucosa, Muscularis Externa, and Serosa (or Adventitia).
p.4
Histology of the Esophagus
What is the composition of the middle 1/3 of the esophagus?
Mixed striated and smooth muscle.
p.12
Functions of the Gastrointestinal Tract
What is the function of the muscularis externa in the duodenum?
Responsible for peristalsis, moving digested food along the small intestine.
p.10
Cell Types in Gastric Glands
How many parietal and chief cells are found in the pylorus?
Few parietal and chief cells.
p.12
Functions of the Gastrointestinal Tract
What is the purpose of the alkaline mucus secreted by Brunner’s glands?
To neutralize the acidic chyme coming from the stomach.
p.9
Cell Types in Gastric Glands
Where are Parietal (Oxyntic) Cells abundant?
In the neck region of gastric glands in the fundus and body.
p.9
Cell Types in Gastric Glands
What is prominent in Chief Cells for enzyme synthesis?
Extensive rough endoplasmic reticulum (ER).
p.17
Histology of the Large Intestine
What is a distinctive histological feature of the large intestine?
The external longitudinal muscles are organized into three thick muscle bands known as taenia coli.
p.4
Histology of the Esophagus
What structures are found in the submucosa of the esophagus?
Submucosal glands and lymph nodes.
p.6
Histology of the Stomach
What type of glands are referred to as fundic glands?
Gastric glands present in both the fundus and body of the stomach.
p.10
Cell Types in Gastric Glands
What is the structure of the glands in the cardia?
Coiled and branched tubular glands.
p.16
Peyer’s Patches in the Ileum
What is the function of M cells in Peyer’s patches?
They take up antigens by endocytosis and transfer them to APC cells.
p.12
Histological Layers of the Gastrointestinal Tract
What are the histological layers of the small intestine?
Mucosa, submucosa, and muscularis externa.
p.3
Functions of the Gastrointestinal Tract
What is the primary function of the muscularis externa?
Responsible for the movement of food along the GI tract, known as peristalsis.
p.12
Histology of the Small Intestine
What is the role of villi in the duodenum?
To increase the surface area for absorption.
p.7
Histology of the Stomach
What is the function of rugae in the stomach?
To allow the expansion of the stomach when food is ingested.
p.7
Histology of the Stomach
What do surface mucous cells secrete?
Alkaline mucus to protect the stomach lining from acid.
p.8
Cell Types in Gastric Glands
What is the isthmus in the context of the fundic glands?
The junction between the gastric pit and the neck, with a high rate of cell proliferation.
p.9
Cell Types in Gastric Glands
How do EC Cells secrete their hormones?
Directly into the capillaries, rather than into the lumen.
p.16
Peyer’s Patches in the Ileum
What does the pale germinal center in lymphoid follicles represent?
The expansion of B cells after antigen stimulation.
p.5
Histology of the Esophagus
What is located beneath the stratified epithelium in the esophagus?
The lamina propria, which is connective tissue supporting the epithelium.
p.5
Histology of the Esophagus
What separates the mucosa from the serosa in the esophagus?
The prominent muscularis, composed of smooth muscle.
p.12
Special Features of the Duodenum
What are plicae circulares?
Circular folds formed by the submucosa, most developed in the duodenum.
p.7
Histology of the Stomach
What type of epithelial cells make up the gastric epithelium?
Columnar epithelial cells.
p.9
Cell Types in Gastric Glands
Where are Chief (Peptic) Cells more commonly found?
At the base of the gastric glands in the fundus and body.
p.6
Histology of the Stomach
What are the two parts of the pylorus?
Pyloric antrum and pyloric canal.
p.1
Functions of the Gastrointestinal Tract
What is the role of the GI tract?
Motility, secretion, digestion, and absorption.
p.3
Histological Layers of the Gastrointestinal Tract
What are the two layers of smooth muscle in the muscularis externa?
The inner layer is arranged circularly, and the outer layer is arranged longitudinally.
p.16
Peyer’s Patches in the Ileum
How do M cells assist B lymphocytes?
By presenting antigens to them.
p.16
Peyer’s Patches in the Ileum
What remains to be investigated regarding M cells?
The full function of M cells and their role in immunity.
p.5
Histology of the Esophagus
What type of muscle is found in the muscularis externa of the esophagus?
Striated muscle in some parts.
p.12
Functions of the Gastrointestinal Tract
How does increasing the pH in the small intestine assist with digestion?
It creates optimal conditions for pancreatic enzymes to function.
p.8
Cell Types in Gastric Glands
What is the function of chief cells?
Synthesis and secretion of pepsin, a digestive enzyme.
p.9
Cell Types in Gastric Glands
What do Enteroendocrine (EC) Cells secrete?
Various hormones to modify functions of other cell types along the GI tract.
