Section 4A Flashcards
The duodenum ends at a sharp bend called what?
Duodenojejunal flexure (junction)
What 4 things are occurring in the duodenum?
- Stomach acid is neutralized here
- Fats are broken up by bile acids
- Pepsin is inactivated by the elevated pH
- Pancreatic enzymes take over the job chemical digestion
How long is the jejunum?
About 8 feet long
How long is the ileum?
About 12 feet long
At what structural point does the ileum join the large intestine?
The ileocecal valve
How does the small intestine maximize its surface area?
Through plicae circulares, villi and microvilli
Which cells produce mucous in the intestinal villi?
Goblet cells
What 3 things do enteroendocrine cells of the intestinal villi secrete?
CCK, Secretin, GIP
What cells of the intestinal vill divide to replace themselves and the other types of epithelial cells?
Regenerative cell
What does the paneth cells do of the intestinal villi?
Secrete the antibacterial enzyme lysozyme and other antibacterial agents
What cells possess a layer of closely packed microvilli, enzymes (brush border) and transporters
Surface absorptive cells
Sucrose, Lactose and Maltose are made up of what simple sugars respectively?
Sucrose: Glucose and Fructose
Lactose: Glucose and Galactose
Maltose: Glucose and Glucose
3 most common examples of Polysaccharides?
Glycogen
Starch
Cellulose
What does pancreatic amylase do?
Degrades polysaccharides into disaccharides and “oligosaccharides”
What enzymes degrade disaccharides in the small intestine?
Brush border enzymes called disaccharidases
What does the Na+-dependent co-transporter SGLT1 do?
It absorbs Gucose and Galactose via secondary active transport
How is Fructose absorbed into the small intestinal cells?
Via GLUT5 by facilitated diffusion
Does the absorption of fructose require Na+
No
How are monosaccharides transported out of the enterocytes and into capillaries?
By GLUT2 via facilitated diffusion
Where does amino acid degradation mainly occur?
Although the stomach does a good job of denaturing proteins, it does not do a good job of denaturing proteins. This occurs mainly at the brush border with aminopeptidases and active pancreatic enzymes
What enzymes at the brush border are the main culprit to cleaving off amino acids
Aminopeptidases
How are MOST amino acids absorbed in small intestine?
By the same co transport mechanism utilized by glucose. However, some amino acids do not require this sodium co-transport but instead are transported like fructose by facilitated diffusion
