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Questions and Answers
What is a primary function of chief cells in the gastric glands?
What is a primary function of chief cells in the gastric glands?
- Production of bile
- Conversion of pepsinogen to pepsin (correct)
- Absorption of nutrients
- Secretion of hydrochloric acid
What characterizes the cytoplasm of chief cells?
What characterizes the cytoplasm of chief cells?
- Acidic and devoid of granules
- High in mitochondria for energy production
- Basophilic due to extensive RER (correct)
- Rich in lysosomes for digestion
What do enteroendocrine cells primarily release?
What do enteroendocrine cells primarily release?
- Hormones into the bloodstream (correct)
- Mucus to protect the stomach lining
- Digestive enzymes
- Nutrients for absorption
Which type of enteroendocrine cell has its apical end in contact with the glandular lumen?
Which type of enteroendocrine cell has its apical end in contact with the glandular lumen?
What is the primary component found in the zymogen granules of chief cells?
What is the primary component found in the zymogen granules of chief cells?
What role do the hormones secreted by enteroendocrine cells play in the gastrointestinal tract?
What role do the hormones secreted by enteroendocrine cells play in the gastrointestinal tract?
Where are chief cells predominantly located within the gastric glands?
Where are chief cells predominantly located within the gastric glands?
What structural feature allows for the identification of chief cells in microscopy?
What structural feature allows for the identification of chief cells in microscopy?
What structure connects the ventral border of the stomach to the anterior abdominal wall?
What structure connects the ventral border of the stomach to the anterior abdominal wall?
What effect does the rotation of the stomach have on the original sides of the stomach?
What effect does the rotation of the stomach have on the original sides of the stomach?
How much does the stomach rotate during its development?
How much does the stomach rotate during its development?
Which nerve supplies the anterior wall of the adult stomach following its rotation?
Which nerve supplies the anterior wall of the adult stomach following its rotation?
What is the consequence of the dorsal border growing faster than the ventral border?
What is the consequence of the dorsal border growing faster than the ventral border?
Which mesogastrium is responsible for suspending the stomach from the dorsal wall of the abdominal cavity?
Which mesogastrium is responsible for suspending the stomach from the dorsal wall of the abdominal cavity?
What happens to the cranial and caudal regions of the stomach during its rotation?
What happens to the cranial and caudal regions of the stomach during its rotation?
What is the primary role of the enzymes within the glycocalyx of microvilli?
What is the primary role of the enzymes within the glycocalyx of microvilli?
What ultimately influences the position of the stomach in relation to the body after rotation?
What ultimately influences the position of the stomach in relation to the body after rotation?
How does the number of microvilli contribute to the absorptive capacity of intestinal cells?
How does the number of microvilli contribute to the absorptive capacity of intestinal cells?
What type of glands are the Crypts of Lieberkühn?
What type of glands are the Crypts of Lieberkühn?
What is the primary secretion of Brunner's glands and its significance?
What is the primary secretion of Brunner's glands and its significance?
Which of the following statements about the distribution of microvilli is correct?
Which of the following statements about the distribution of microvilli is correct?
What function does the muscularis mucosa serve in relation to the glands of the small intestine?
What function does the muscularis mucosa serve in relation to the glands of the small intestine?
Why is the secretion from Brunner's glands particularly important in the upper duodenum?
Why is the secretion from Brunner's glands particularly important in the upper duodenum?
What characteristic distinguishes Brunner's glands from other intestinal glands?
What characteristic distinguishes Brunner's glands from other intestinal glands?
What happens to the dorsal mesoduodenum during development?
What happens to the dorsal mesoduodenum during development?
What is the outcome of the proliferation of epithelial cells in the duodenum during the fifth and sixth weeks?
What is the outcome of the proliferation of epithelial cells in the duodenum during the fifth and sixth weeks?
What does the cranial part of the hepatic diverticulum develop into?
What does the cranial part of the hepatic diverticulum develop into?
What is the smaller caudal part of the hepatic diverticulum known as?
What is the smaller caudal part of the hepatic diverticulum known as?
What structure does the stalk of the hepatic diverticulum form?
What structure does the stalk of the hepatic diverticulum form?
What occurs to the epithelial cells of the duodenum as they degenerate?
What occurs to the epithelial cells of the duodenum as they degenerate?
At which point does the duodenum typically become recanalized?
At which point does the duodenum typically become recanalized?
Which structure listed is NOT associated with the development of the liver and biliary apparatus?
Which structure listed is NOT associated with the development of the liver and biliary apparatus?
What part of the foregut do dorsal and ventral pancreatic buds arise from?
What part of the foregut do dorsal and ventral pancreatic buds arise from?
What happens to the ventral pancreatic bud during the rotation of the duodenum?
What happens to the ventral pancreatic bud during the rotation of the duodenum?
Which duct develops into the main pancreatic duct?
Which duct develops into the main pancreatic duct?
What happens initially to the dorsal and ventral pancreatic ducts?
What happens initially to the dorsal and ventral pancreatic ducts?
Which structure persists as the accessory pancreatic duct?
Which structure persists as the accessory pancreatic duct?
What is the origin of the parenchyma of the pancreas?
What is the origin of the parenchyma of the pancreas?
During histogenesis, from what do pancreatic acini begin to develop?
During histogenesis, from what do pancreatic acini begin to develop?
What occurs between the dorsal and ventral duct during development?
What occurs between the dorsal and ventral duct during development?
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Study Notes
Chief Cells (Zymogenic Cells)
- Predominant in the lower region of gastric tubular glands, specifically in the basal half of gastric glands in the body and fundus.
- Ultrastructure shows abundant rough endoplasmic reticulum (RER) in basal cytoplasm and numerous apical zymogen granules.
- Zymogen granules contain inactive enzymes: pepsinogens and gastric lipase.
- Pepsinogen is converted to the active proteolytic enzyme pepsin upon contact with acidic gastric juice.
- Basophilic cytoplasm is due to extensive RER presence.
Enteroendocrine Cells
- Scattered in the base of gastric glands; two main types identified: "closed" and "open."
- "Closed" type lacks direct contact with glandular lumen; "open" type interfaces with lumen.
- Difficult to identify with routine preparations; revealed via electron micrographs.
- Contains small membrane-bound secretory vesicles in basal cytoplasm for hormone storage.
- Hormonal secretions regulate peristalsis, digestive enzyme secretion, and satiation after meals.
Microvilli
- Each absorptive cell has about 3000 microvilli, significantly increasing surface area by 20-30 fold.
- 1 mm² of intestinal mucosa contains approximately 200 million microvilli.
- Microvilli are coated with glycocalyx which contains essential brush-border enzymes like lactase and lipase.
Crypts of Lieberkühn
- Simple tubular glands within the intestinal mucosa that extend from the muscularis mucosa to the intestinal lumen.
- Responsible for producing digestive enzymes and secreting intestinal juices.
Duodenal (Brunner's) Glands
- Compound branched tubular mucous glands located in the submucosa of the upper duodenum.
- Excretory ducts open into the intestinal crypts, releasing alkaline secretions (pH 8.1–9.3) to neutralize chyme.
- Protects mucous membranes and creates optimal pH levels for pancreatic enzymes.
Development of the Stomach
- The stomach undergoes a 90-degree clockwise rotation around its longitudinal axis during enlargement.
- The dorsal border (greater curvature) grows faster than the ventral border (lesser curvature).
- Vagal innervation results from the stomach's rotation: the left vagus nerve supplies the anterior wall while the right vagus innervates the posterior wall.
Mesenteries of the Stomach
- The stomach is anchored to the dorsal abdominal wall via a dorsal mesentery, which later diminishes, fixing the duodenum and pancreas in retroperitoneal positions.
Development of the Liver and Biliary Apparatus
- The hepatic diverticulum is a ventral outgrowth from the foregut during the fourth week of development.
- Divided into two parts: the larger cranial part (pars hepatica) primordium of the liver and the smaller caudal part (pars cystica) forming the gallbladder and cystic duct.
Pancreas Development and Duct System
- Initially, dorsal and ventral pancreatic ducts open separately, later forming connections.
- The main pancreatic duct develops from the dorsal duct, while the proximal part of the dorsal duct remains as the accessory pancreatic duct.
- Basic cellular tissue derives from endoderm of pancreatic buds, with acini developing from cell clusters at primordial duct ends.
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