Anatomy of the Stomach and Duodenum

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the characteristic of the pyloric glands?

Simple, branched, coiled tubular glands (correct)

Simple, branched, coiled tubular glands located in the duodenum

Simple, unbranched, tubular glands located in the small intestine

Compound, branched, coiled tubular glands found in the stomach

What is the function of the thick smooth muscle layer in the pyloric sphincter?

To mix food with gastric juices

To separate the pylorus from the duodenum (correct)

To absorb nutrients

To secrete digestive enzymes

Where is the myenteric plexus located in the tunica muscularis?

Between the middle circular and outer longitudinal muscle layers (correct)

Between the outer longitudinal and serosa layers

In the submucosa

Between the innermost oblique and middle circular muscle layers

What is the characteristics of the tunica muscularis in the pyloric region?

It has a clearly evident middle circular layer Signup and view all the answers

What is the characteristic of the submucosal intestinal glands?

They extend into the submucosa of the pyloric gland region from the duodenum Signup and view all the answers

Which part of the compound stomach is glandular?

The fourth part Signup and view all the answers

What percentage of the abomasum is composed of pyloric gland region in ruminants?

1/3 Signup and view all the answers

Which type of cells in the fundic gland is responsible for producing soluble mucus?

Mucous neck cells Signup and view all the answers

What is the function of oxyntic cells in the fundic gland?

Producing hydrochloric acid and gastric intrinsic factor Signup and view all the answers

In which region of the fundic gland are chief cells predominantly located?

Base Signup and view all the answers

What is the function of regenerative cells in the fundic gland?

Replacing specialized cells Signup and view all the answers

In which region of the pyloric gland are mucus-secreting cells predominantly located?

Pyloric gland region Signup and view all the answers

What is the percentage of pyloric gland region in the gastric mucosa of horses?

1/3 Signup and view all the answers

What is the percentage of pyloric gland region in the gastric mucosa of carnivores?

Approx. ½ Signup and view all the answers

What is the primary function of the Brunner's gland in the duodenum?

To produce mucous-rich fluid and urogastrone Signup and view all the answers

What is the characteristic of the villi in the jejunum compared to the duodenum?

They are slender and more sparse Signup and view all the answers

What is the primary function of the microvilli in the small intestine?

To increase the surface area for absorption Signup and view all the answers

What is the characteristic of the ileum compared to the duodenum and jejunum?

It has narrower, sparsest, and shortest villi Signup and view all the answers

What is the function of the Crypts of Lieberkuhn in the small intestine?

To form the intestinal glands Signup and view all the answers

What is the characteristic of the muscularis mucosae in the small intestine?

It has both an inner circular and outer longitudinal layer Signup and view all the answers

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