20 Questions
What is the characteristic of the pyloric glands?
Simple, branched, coiled tubular glands
What is the function of the thick smooth muscle layer in the pyloric sphincter?
To separate the pylorus from the duodenum
Where is the myenteric plexus located in the tunica muscularis?
Between the middle circular and outer longitudinal muscle layers
What is the characteristics of the tunica muscularis in the pyloric region?
It has a clearly evident middle circular layer
What is the characteristic of the submucosal intestinal glands?
They extend into the submucosa of the pyloric gland region from the duodenum
Which part of the compound stomach is glandular?
The fourth part
What percentage of the abomasum is composed of pyloric gland region in ruminants?
1/3
Which type of cells in the fundic gland is responsible for producing soluble mucus?
Mucous neck cells
What is the function of oxyntic cells in the fundic gland?
Producing hydrochloric acid and gastric intrinsic factor
In which region of the fundic gland are chief cells predominantly located?
Base
What is the function of regenerative cells in the fundic gland?
Replacing specialized cells
In which region of the pyloric gland are mucus-secreting cells predominantly located?
Pyloric gland region
What is the percentage of pyloric gland region in the gastric mucosa of horses?
1/3
What is the percentage of pyloric gland region in the gastric mucosa of carnivores?
Approx. ½
What is the primary function of the Brunner's gland in the duodenum?
To produce mucous-rich fluid and urogastrone
What is the characteristic of the villi in the jejunum compared to the duodenum?
They are slender and more sparse
What is the primary function of the microvilli in the small intestine?
To increase the surface area for absorption
What is the characteristic of the ileum compared to the duodenum and jejunum?
It has narrower, sparsest, and shortest villi
What is the function of the Crypts of Lieberkuhn in the small intestine?
To form the intestinal glands
What is the characteristic of the muscularis mucosae in the small intestine?
It has both an inner circular and outer longitudinal layer
Study Notes
Pyloric Glands
- Simple, branched, coiled tubular glands located in deeper gastric pits
Pylorus to Duodenum
- Pyloric sphincter: thick smooth muscle layer that separates pylorus from duodenum
- Submucosal intestinal glands may extend into the submucosa of the pyloric gland region from the duodenum
Tunica Muscularis and Serosa
- Tunica muscularis: innermost oblique (not well-defined except in cardia), middle circular (clearly evident especially in pyloric region), outer longitudinal (most evident in cardia, poorly developed in pylorus)
- Myenteric plexus located between the middle and outer muscle layers
- Tunica serosa covers the entire stomach
Compound Stomach
- Forestomach (non-glandular): rumen/panch, reticulum/honeycomb, omasum/book
- Glandular: 2/3 of abomasum in ruminants
Fundic Glands
- Simple, straight, branched, tubular glands
- 3 distinct regions: isthmus, neck, base
- Cell types:
- Surface lining cells: produce thick mucus layer
- Parietal (oxyntic) cells: produce hydrochloric acid, gastric intrinsic factor
- Regenerative (stem) cells: replace specialized cells
- Mucous neck cells: produce soluble mucus
- Chief (zymogenic) cells: produce enzymes
- Diffuse neuroendocrine (DNES) cells: produce endocrine, paracrine, neurocrine hormones
- Distribution of cell types in fundic glands:
- Isthmus: surface-lining cells, few DNES
- Neck: mucous neck cells, regenerative cells, parietal cells, few DNES
- Base: chief cells, occasional parietal cells, few DNES
Pyloric Gland Region
- Similar to cardiac gland region
- Cells appear as typical mucus-secreting cells
Surface Modifications of Small Intestine
- Microvilli: modifications of apical surface of epithelial cells
- Crypts of Lieberkuhn: invaginations of the epithelium into the lamina propria, forming intestinal glands
- Muscularis mucosae: inner circular, outer longitudinal
Tunica Submucosa and Muscularis
- Tunica submucosa: Brunner's gland (duodenal/submucosal glands) produces mucous (bicarbonate-rich) fluid and urogastrone
- Tunica muscularis: inner circular, outer longitudinal
This quiz covers the structure and organization of the stomach and duodenum, including the pyloric glands, pyloric sphincter, and tunica muscularis.
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