GI 15 Flashcards
What are the two types of micronutrients?
- Vitamins
* Trace elements
What are the fat soluble vitamins?
A, E, D
What is the main goal of carbohydrate digestion?
To break those long chains down into oligo/disaccharides
What is one of the most important enzymes for carbohydrate digestion?
Amylase
Where does Amylase in carbohydrate digest originate?
In the pancreas
What kind of enzyme is Amylase?
An alpha (1,4) endoglycosidase
How is the meaning of amylase being an endoglycosidase?
It cleaves glycosidic bonds between subunits of polysaccharides
What happens once amylase breaks down the polysaccharide into a disaccharide?
To break it down into monosaccharides
What is the breakdown of disaccharides into monosaccharides facilitated by?
The brush border enzymes of the SI
What are brush border enzymes?
Enzymes in the SI intestine that are specific for breaking down different disaccharides
What are three brush border enzymes?
- Maltase
- Sucrase
- Lactase
What does Maltase do?
Breaks down Maltose into two glucoses
What does Sucrase do?
Breaks down sucrose into glucose and fructose
What does Lactase do?
Breaks down lactose into glucose and galactose
What happens when somebody lacts Lactase?
They have lactose intolerance and further down the line the unbroken down lactose can affect water balance
What happens once disaccharides are cleaved into monosaccharides?
They can be absorbed across the intestinal epithelium
What kind of transport is used for the absorption of Glucose/galactose?
Secondary active transport
Which transporter brings glucose into the intestinal epithelial cell?
SGLT, the sodium glucose transport
How does SGLT-1 (sodium glucose cotransporter) work?
It brings glucose into the intestinal epithelial cell by bringing one molecule of glucose/galactose along with two Na+ down its conc. gradient
How does Glucose/Galactose exit the intestinal epithelial cell?
It diffuses through facilitated diffusion through the GLUT2
What does GLUT2 do?
Allows glucose/galactose and fructose to exit the intestinal epithelial cell through facilitated diffusion
What maintains the conc gradient when SGLT-1 is working?
The sodium potassium ATPase
How does Fructose enter the intestinal epithelial cell?
By facilitated diffusion through GLUT5
What does GLUT5 do?
Allows fructose to enter the intestinal epithelial cell through facilitated diffusion
How does Fructose exit the intestinal epithelial cell?
Through facilitated diffusion GLUT2
What are the levels of glucose in the GI when there is a high sugar meal?
There are higher levels of glucose/galactose
What happens if there are higher levels of glucose/galactose in the GI lumen?
It saturates the proteins so the gradients don’t work effectively
What does intestinal epithelial cells do when there is a high sugar meal?
They translocate GLUT2 proteins to the lumen in order to allow facilitated diffusion of the sugar into the cell
When will GLUT2 be found at the apical membrane of carbohydrates?
When there is a high sugar meal
What is the overview of how carbohydrates are broken down?
- Polysaccharides acted on by pancreatic amylase to create disaccharides
- Disaccharides are acted on by brush border enzymes to create monosaccharides (glucose/galactose and fructose)
- They are brought across the apical surface by SGLT and GLUT
What is the difference between the transport of fructose and glucose/galactose?
Glucose/galactose is brought in through secondary active transport and glucose is brought in by facilitated diffusion
What are plant polysaccharides classified as?
Dietary fiber
What are examples of dietary fiber?
- Cellulose
- Lignin
- Chitin
What are the benefits to consuming Fiber?
- Delayed gastric emptying
- Impaired absorption in the small intestine
- Fiber fermentation in the large intestine
- Fecal bulking
How does fiber causing increased satiety work?
It takes up more room causing the stomach to fill up faster and in turn making people consume less
How does fiber delaying absorption in the GI work?
It traps carbs in its network and the delayed absorption increases glucose control and cholesterol and even toxic elements
How is fiber fermentation in the LI a good thing?
Bacteria can break them down and use the fatty acids as energy
What is fecal bulking?
When undigested fiber can retain water and have other benefits on feces and make it easier to pass
