4A A&P and Pathology of Small Intestine Flashcards
How long is the duodenum?
First 10-12 inches of the small intestine
Where does the duodenum end?
Duodenojejunal flexure
How long is the jejunum? Ileum?
8 feet long.
12 feet long
What is the longest section of the small in intestine? Shortest?
Ileum is the longest. Duodenum is the shortest
How is maximal surface area achieved in the small intestine?
Via plicae circulares, villi, and microvilli
What are plicae circulares?
Finger-like extensions in the lumen of the small intestine - Macrovilli
What is the difference between villi and microvilli?
Villi project off of the plicae circulares. Microvilli project off of individual cells (enterocytes) that make up the villi
Are villi present in the large and small intestine?
Only in the small intestine
What kind (shape) of cells are enterocytes?
Tall columnar cells
Are crypts present in the large and small intestine?
Yes, the both have crypts
What is in the core of each villus?
Blood (vein and artery) capillaries and lymphatic capillaries
What is the crypt of Liberkuhn?
The crypts of the small and large intestine that are lined with a variety of enterocytes
What kind of cells line the crypts and villi of the small intestine?
Surface absorptive cells, goblet cells, enteroendocrine cells, regenerative cells, and paneth cells
What do goblet cells produce?
Mucus
What do enteroendocrine cells produce?
CCK, secretin and GIP
Where are regenerative cells found in the small intestine?
Bottom of the crypts
What are Paneth cells?
Secrete the antibacterial enzyme lysozyme and other antibacterial agents
What are three common monosaccharides?
Glucose, Fructose, Galactose
What are three common disaccharides?
Sucrose (glucose and fructose), lactose (galactose and glucose), maltose (glucose and glucose)
What are three common polysaccharides?
Glycogen, starch, cellulose
Are there any enzymes in the stomach that breakdown carbs?
No
What does pancreatic amylase breakdown?
Polysaccharides into disaccharides and oligosaccharides
What are disaccharides degraded by?
A group of brush border enzymes called disaccharidases
How do glucose and galactose get absorbed in the small intestine?
Via SGLT1 (secondary active transport)
Can glucose and galactose be absorbed in the small intestine w/o a sodium gradient?
No, glucose and galactose rely on the sodium gradient to go into the enterocytes against their own gradient
What is the only way that the small intestine can absorbed glucose into the body?
Via the SGLT1 cotransporter
What does GLUT5 facilitate?
Absorption of fructose by facilitated diffusion
How are monosaccharides transported out of the enterocytes and into the capillaries?
Via GLUT2 (facilitated diffusion)
How does hyponatremia affect carb absorption?
When sodium concentration is low, glucose is not able to be absorbed via the SGLT1
What monosaccharides can move thru GLUT2?
Glucose, galactose, and fructose
Why does lactose intolerance occur?
Lack of the lactase enzyme
Where does the cleaving off of amino acids occur mainly?
At the brush border w/ aminopeptidases and with the active pancreatic enzymes (proteases)
T/F most amino acids or small peptides are transported into enterocytes via the same co-transport mechanism as utilized by glucose?
T but some do not require the sodium co-transport mechanism by instead are taken in the same way as fructose - via facilitated diffusion
