12 Questions
Describe the composition of the lining epithelium of the small intestine mucosa.
The lining epithelium of the small intestine mucosa is composed of absorptive enterocytes, goblet cells, and occluding junctions that prevent content from diffusing. Enterocytes have an ovoid nucleus, microvilli, and a well-developed smooth endoplasmic reticulum. Goblet cells synthesize mucinogen and produce mucus that forms a protective film on the intestinal surface.
What is the function of the lamina propria in the small intestine mucosa?
The lamina propria is richly vascularized and innervated loose connective tissue containing immune cells, diffuse lymphoid tissue, and lymphatic vessels. It also contains intestinal glands (crypts of Lieberkühn) that produce absorbent columnar cells and goblet cells.
What is the role of Paneth cells in the small intestine mucosa?
Paneth cells, also known as eosinophilic granular cells, produce antimicrobial components and are located at the base of the crypts in the small intestine mucosa.
Explain the structure and function of the muscularis mucosae in the small intestine.
The muscularis mucosae consists of two layers of smooth muscle, internal circular and external longitudinal, and is responsible for the peristaltic movements of the intestine.
What are Brünner's glands and where are they located?
Brünner's glands are glands that produce mucous secretions and are located in the duodenum and horse intestines.
What is the function of the Auerbach's myenteric plexus?
The Auerbach's myenteric plexus is responsible for innervating the muscularis in the submucosa of the small intestine.
Describe the role of the large intestine in microbial action and absorption.
The large intestine is responsible for microbial action, absorption of water, electrolytes, and vitamins. In horses and pigs, it also absorbs fatty acids produced by microbial digestion of cellulose.
What is the responsibility of the small intestine mucosal glands (crypts of Lieberkühn)?
The small intestine mucosal glands are responsible for the renewal of the intestinal epithelium by producing absorbent columnar cells and goblet cells. At the base of the crypts, undifferentiated cells multiply, differentiate, and migrate to the villi, where they give rise to new cells.
What is the role of apoptosis in the small intestine mucosa?
Apoptosis is a physiological process through which cells at the apex of the villi die and shed into the lumen.
What are the endocrine cells of the APUD system responsible for in the small intestine mucosa?
The endocrine cells of the APUD system, also known as enteroendocrine cells, secrete hormones and regulate the peristaltic movements of the gastrointestinal tract and its secretions.
What is the function of Peyer's patches in the lamina propria of the small intestine mucosa?
Peyer's patches contain M cells, which capture antigens from the intestinal lumen and present them to lymphocytes.
What are the components that the enterocytes in the lining epithelium of the small intestine mucosa absorb?
Enterocytes absorb amino acids, monosaccharides, and immunoglobulins.
Study Notes
- The small intestine mucosa consists of the lining epithelium, lamina propria, and muscularis mucosae.
- Lining epithelium: simple columnar epithelium composed of absorptive enterocytes, goblet cells, and occluding junctions that prevent content from diffusing. Enterocytes have an ovoid nucleus, microvilli, and a well-developed smooth endoplasmic reticulum. They absorb amino acids, monosaccharides, and immunoglobulins. Goblet cells synthesize mucinogen and produce mucus that forms a protective film on the intestinal surface.
- Lamina propria: richly vascularized and innervated loose connective tissue containing immune cells (plasma cells, lymphocytes, mast cells, and eosinophils), diffuse lymphoid tissue, and lymphatic vessels. Lymphoid follicles (Peyer's patches) contain M cells, which capture antigens from the intestinal lumen and present them to lymphocytes. Intestinal glands (crypts of Lieberkühn) are located in the lamina propria and produce absorbent columnar cells and goblet cells. Eosinophilic granular cells (Paneth cells) produce antimicrobial components.
- Muscularis mucosae: consists of two layers of smooth muscle, internal circular and external longitudinal. It is responsible for the peristaltic movements of the intestine.
- Submucosa: loose connective tissue containing glands (Brünner's glands) and lymphoid follicles. Brünner's glands produce mucous secretions and are located in the duodenum and horse intestines. Lymphoid follicles are present in the small intestine and are more numerous in horses. The nervous plexus Auerbach's myenteric plexus is located in the connective tissue and is responsible for innervating the muscularis.
- Large intestine: made up of the caecum, colon, and rectum. Microbial action occurs in the large intestine, water, electrolytes, and vitamins are absorbed, and in horses and pigs, fatty acids produced by microbial digestion of cellulose are absorbed.
- The small intestine mucosal glands (crypts of Lieberkühn) are responsible for the renewal of the intestinal epithelium by producing absorbent columnar cells and goblet cells. At the base of the crypts, undifferentiated cells multiply, differentiate, and migrate to the villi, where they give rise to new cells. Cells at the apex of the villi die and shed into the lumen through a physiological process called apoptosis. Eosinophilic granular cells (Paneth cells) produce antimicrobial components and are located at the base of the crypts. The endocrine cells of the APUD system (enteroendocrine cells) secrete hormones and regulate the peristaltic movements of the gastrointestinal tract and its secretions.
Test your knowledge on the functions of the small intestine in the digestive system. Learn about its role in digestion, absorption, and the different parts of the small intestine.
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