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33 terms

Active transport of carbs in small intestine

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SGLT transporter transports glucose into the intestinal cell but it has an obligation to bind first to __________
sodium
The faciliated diffusion of glucose into the blood is brought by ________ transporters
GLUT
___________ is the type of process that moves NA+ and glucose into the cell.
co-transport
The Na/K pump ATPase pump creates a sodium __________ in the cell so NA can enter the cell bringing glucose with it
gradient
At what temperature was the intestinal segments incubated to mimic the body temp of the rat?
37 degrees celsius
What are the structures that increased the surface area of absorption in the intestine?
villi
Enzyme that breaks down starch in mouth
salivary
Dietary carbs are mostly?
starches and disaccharides.
Can starches and disaccharides cross the cell membrane of the intestinal epithelium?
no. They must be first digested to monosaccharides in order to be absorbed.
Starch is digested to ____________ by _________and _______________?
maltose salivary and pancreatic amylases.
What are the disaccharides?
Maltose
lactose
sucrose
What do the disaccharides come in contact with to be broken down to monosaccharides?
intestinal brush border hydrolases which are,
maltase, lactase, sucrase
What is the portal for absorption of virtually all nutrients into the blood?
small intestine
Absorption of glucose from the intestinal lumen into the blood is what type of process?
active
How is glucose absorbed or transported to blood?
transport from the intestinal lumen, across the epithelium and thereafter into blood.
How is absoprtion of glucose from the lumen into the enterocyte is only done by
cotransport with NA+
What is the transporter SGLUT-1?
carries glucose (and galactose) into the enterocyte. It is a Na+ dependent hexose transporter.

This molecule transports both glucose and sodium ion into the cell and in fact, will not transport either of them alone.
The important process that makes absorption possible is the establishment of?
electrochemical gradient of Na+ across the luminal membrane of the epithelial cells.
What is responsible for establishing electrochemical gradient?
Na+/K+ pump ATPases (sodium pumps) of the basolateral membrane
What are the sodium pumps ultimately responsible for?
absorption of monosaccharides, water, and amino acids.
Fructrose enters the cell from the intestinal lumen by?
facilitated diffusion using a different transporter
What happens to glucose and Na+ once inside the enterocyte?
exported from the cell into blood
What hexose transporter in the basolateral membrane transports t _____, _______, _________, ________out of the enterocyte?
simple sugars, glucose, galactose, fructose. GLUT-2
What happens with the serosal side of the intestine?
Starch when placed in contact with the mucosal side would be digested, and actively absorbed resulting in an increase in the glucose concentration on the serosal side.
If a segment of intestinal wall separates glucose of equal concentration, despite the absence of concentration gradient, the transport of glucose?
akes place across the wall from mucosal to serosal compartment. This can only be attributed to an active transport that is accompanied by expenditure of energy. Since ATP generation needs O2, a reduction in its concentration will abate the process.
ATP required for active transport
from aerobic respiration. Active transport can't happen if no Os
Was there transport of starch across the intestinal epithelium?
no. because no carrier molecules
Salivary amylase breaks down
polysaccharides to disachharide
Gastric HCl
inhibits breakdown of sugars in stomach (temporarily) so sugars can get to pancreatic juices to breakdown more
Pancreas
amylase released here. dissacharrides to monosacharrides
Brush border enzymes used
brush border enzymes used. located on luminal side of membrane of small intestine.
Any transport of glucose in anareobic conditions?
no, Ox is needed for active transport of glucose. ATP requires O2
How might eating a meal hgih in NaCl concentration aid in absorption of glucose or some amino acids?
Using the co-transport of glucose. Na+ and glucose bind to SGLT transporter molecule. The Na+ will be higher in the ECF. The elctrochemical gradient will be steeper because of high concentration outside than inside of cell. The gradient of Na+ provides the energy for moving glucose against its concentration gradient (glucose low to high in cell but uses Na+ to move it. 1 glucose high to low outside cell uses facilitated diffusion.

2Na+ high to low concentration in cell moves in, picks up 1 Na+, 3 move out through Na+/K+ pump because goes low-high.