What are the three anatomical portions of the small intestine?
Duodenum
Jejunum
Ileum
Which region of the stomach is shortest and widest?
Duodenum
What are 5 functions of the small intestine?
Food digestion - principal site
Absorption of food
Synthesis and secretion of digestive enzymes
Control microbial growth within lumen of intestine
Regulate GI functions via endocrine secretion by enteroendocrine cells
What are plicae cirulares? What is their core made of? Where are they most numerous? What is their purpose?
Permanent transverse folds
Core of submucosa
Most numerous in distal duodenum and proximal jejunum
Increase surface for absorption
Where are villi found in the GI tract?
Small Intestion
What forms the core of villi? What is their function?
Lamina propria
Increase surface area of small intestine
What causes gluten enteropathy (coeliac disease)? What clinically will be seen?
Total or subtotal atrophy of villi in small intestine
Malabsorption (weightloss and steatorrhea)
What general type of cell composes surface epithelium of the small intestine? Does this differ between villum and intervillous surface?
Simple columnar
No
What are 5 types of cells found in the small intestine? Which is most abundant?
Enterocytes (intestinal absorptive cells) - most prominent Goblet cells M-cells Enteroendocrine cells Intraepithelial lymphocytes
What do enterocytes produce? Where are they used for the terminals stages of digestion for carbohydrates and proteins?
Digestive enzymes
Occur with glycocalyx of intestinal absorptive cells
Where are lipids broken down in the small intestine? What happens once they are transported into the enterocyte? Where are their final forms released?
Lumen
Re-syntehsized into trigylcerides in SER
Acquire protein coat in golgi apparatus,becoming chylomicra
Basolateral surface of absorptive cell
Where is IgA made? How does it get to the lumen of the intestine?
Synthesized and secreted by plasma cells
Absorbed by enterocytes and released apically into lumen of small intestine
How many microvilli are on each enterocyte? How manya re in one square millimeter?
3,000
200,000,000
What binds the apical portions of enterocytes together? What do they keep separate?
Tight and anchoring junctions
Lumen and intercellular epithelial compartment
How does the number of goblet cells change from duodenum to ileum?
Increase in number
How does the cytoplasm of a goblet cell appear under a microscope? What is the shape and color of their nuclei?
Frothy
Small, triangular, and heterochromatic
What is the function of M-cells? What are they only found overlying? Shape?
Antigen-transporting cells
Lymphoid follicles
Dome shaped
What are intraepithelial lymphocytes an unusual type of? What are they derived from? What process are they involved in?
T-cells
Blood
Mucosal immunity
What are crypts of Lieberkuhn invaginations of? Where are they found in relation to villi?
Invaginations of surface epithelium
Found at base of villi
What two types of cells can be found in crypts of Lieberkuhn but not in within normal surface epithelia? Function?
Paneth cells - regulate normal bacteria growth
Progenitor cells - Replacement cells for all surface epithelia (except intraepithelial lymphocytes)
What is the most prominent feature of Paneth cells? Where are they found within the cell?
Large eosinophilic granules at apical surface
Where are lymphoid follicles located in the small intestine? In what layer? All together, what do they form?
Scattered throughout intestine
Lamina propria
GALT
What are large associations of lymphoid follicles called? Where are they located? Can they be seen by the naked eye? What cell type mainly covers them?
Peyer’s patch
Ileum
Yes
M-cell
What is one of the most common types of cancers within the small intestine? Distal or proximal? What does the wall become thickened/infiltrated with?
Small intestine lymphoma
Proximal
Lymphocytes
