Lecture 4 Flashcards
What percentage of nutrients and electrolytes are absorbed in the small intestine?
100% nutrients, 90% electrolytes
What are the large folds of the small intestine called?
Folds of circ
What percentage of all immune cells are in the small intestine?
80%
What cells in the crypts protect stem cells?
Paneth cells
What type of cells proliferate rapidly and move up the walls of the crypts?
Transit-amplifying cells
What two types of villous epithelial cells do the transit-amplifying cells become?
Absorptive cells and goblet cells.
How many cells a day are lost from the top of the villous?
1.7 billion
What cells cause colon cancer?
Any cells retained within the crypts.
The loss of what protein blocks out-migration?
APC
What does APC normally inactivate?
Beta-catenin.
What do tight junctions do to the epithelium?
prevents free movement of material between the cells and also polarises the cells.
What are two examples of impenetrable tight junctions?
Thick ascending limb and urinary bladder
Where is there a cation selective tight junction?
The ileum
What does a short circuit current measure?
Charge moving across an epithelium
What do radiotracer experiments determine?
Which ion is moving
