10 Questions
What is the pH range of the secretions produced by the duodenal (Brunner) glands?
pH = 8.1-9.3
What is the primary location of lipid absorption in the human body?
Duodenum and upper jejunum
What is the approximate increase in the surface area of the intestinal lining due to the presence of plicae, villi, and microvilli?
600 fold
What is the name of the lymph vessels that begin as blind tubes in the core of villi?
Lacteals
What is the primary enzyme responsible for lipid digestion?
Pancreatic lipase
What is the characteristic of the mucosal membrane in the intestine?
It has no folds except in the rectal portion
What is the main function of the intestinal glands?
Production of mucus and absorption of water
Why is the lamina propria rich in lymphoid cells and nodules?
Due to the extremely abundant bacterial population of the large intestine
What is the mechanism by which epithelial cells in the gastrointestinal tract are replaced?
Through mitosis of stem cells
Which part of the intestine has a unique mucosal membrane structure?
Rectum
Study Notes
Duodenal (Brunner) Glands
- Secrete alkaline secretions with a pH range of 8.1-9.3
- Serve two purposes:
- Protect the duodenal mucosa from gastric acids
- Provide the optimal pH for pancreatic enzyme action
Lymph Vessels of the Intestine
- Begin as blind tubes in the core of villi
- Referred to as lacteals
Histophysiology of the Intestine
- Presence of plicae, villi, and microvilli increases the surface area of the intestinal lining
- This increased surface area results in a 600-fold increase in the intestinal surface
Lipid Digestion and Absorption
- Lipid digestion occurs mainly due to the action of pancreatic lipase and bile
- Most lipid absorption occurs in the duodenum and upper jejunum in humans
Intestine (L.I.)
- Consists of appendix, cecum, colon, rectum, and anal canal, with the colon divided into ascending, transverse, descending, and sigmoid parts
- Mucosal membrane has no folds except in the rectal portion, and no villi are present
- Intestinal glands are long and contain many goblet cells, absorptive cells, and few enteroendocrine cells
Functions of the Intestine
- Absorption of water
- Formation of fecal mass
- Production of mucus
Lamina Propria
- Rich in lymphoid cells and nodules
- Richness is due to the extremely abundant bacterial population of the L.I.
Cell Renewal in the Gastrointestinal Tract
- Epithelial cells of the entire G.I. tract are constantly being replaced by new ones formed through mitosis of stem cells
This quiz covers the structure and function of the intestinal lining, including the role of Brunner glands and villi in digestion.
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