Lecture 22: THE SMALL INTESTINE Flashcards
What are the regions of the small intestine (in order)?
Duodenum, jejunum and ileum
What is the largest region of the small intestine?
Ileum
What is the total length of the small intestine?
About 6m
Where is the initial segment of the small intestine?
Retroperitoneal
What is the small intestine held in place by?
Mesentery
What does the mesentery allow?
Movement, but prevents the small intestine from getting tangled
What does the mesentery contain?
Arteries, veins, nerves and lymphatics
What is delivered to the small intestine?
Chyme which is acidic
What is needed because of chyme being acidic?
Protect the epithelium and neutralise pH
How is the epithelium protected?
By mucous secreting cells and glands in the submucosa (specifically in the duodenum)
How is pH neutralised?
By bicarbonate (HCO3-) from the pancreas
What are plicae circulares?
Permanent folds of the small intestined
What is the structure of plicae circulares?
Core of submucosa with overlying mucosa
Where are villi found?
On the surface of the plicae circulares
What does the muscularis mucosae allow?
Villi to wiggle back and forth
What are villi?
Folds of the mucosa
What is the core of each villus?
FCT (lamina propria)
What do villi contain?
Vessels
What vessels do villi contain?
Lymph lacteal and capillary network
What is drained into the lymph lacteal?
Products of fat digestion
What is drained into the capillary network?
Products of protein and carbohydrate digestion
What enters the mesenteric veins?
Nutrient rich, deoxygenated blood absorbed in the small intestine
What do mesenteric veins drain into?
Hepatic (liver) portal vein
What do lymph lacteals drain into?
The cisterna chyli, thoracic duct and then left subclavian vein
