Digestion and absorbtion

Question 1

Sucrose and lactose are examples of what sort of carbohydrates?

Answer 1

Short polyermer Oligosaccharides.

Question 2

Following digestion, glucose and galactose are transported into the intestinal enterocyte via…

Answer 2

Sodium-glucose transporter SGLT-1
and
Fructose via the glucose transporter GLUT-5.

Question 3

What is the responsibility of Glut-2?

Answer 3

Glut 2 transports all three monosaccharides (Fructose, glucose, and galactose) across the basolateral membrane.

Question 4

Which transporter moves Fructose into the enteric small intestinal cells?

Answer 4

Glut 5

Question 5

Pept1 is responsible for what?

Answer 5

Allows for the transport of oligopeptides and H+ across the apical membrane of the intestine.

Question 6

Transporter B has what responsibility?

Answer 6

Transporter B moves amino acids across the apical border of the intestinal enterocytes along with sodium.

Question 7

Describe the difference between lipid digestion in the stomach vs in the intestine.

Answer 7

In the stomach, lingual lipase and gastric lipase digest lipids and are active at low pH (resistant to pepsin digestion)

When these lipases pass into the duodenum they are degraded by pancreatic proteases (Trypsin) and pancreatic lipases take over.

Question 8

Niemann Pick C1 Like1 (NPC1L1) is responsible for what?

Answer 8

This transporter is responsible for absorbing cholesterol.

Question 9

What are the components of chylomicrons?

Answer 9

Chylomicrons are composed of lioproteins and lipids!

These are placed into the circulation where they will be absoarbed by the liver.

Question 10

Where and how is Folic acid absoarbed?

Answer 10

Mostly absoarbed in the duodenum

The uptake occurs via an exchange protein expressed on the surface of enterocytes.

Question 11

What is required for the absorption of vitamin B12 and where is it absoarbed?

Answer 11

Intrinsic factor secreted from parietal cells of the stomach are required for its absorption

Once IF and B12 pass into the duodenum they form a complex that can then be takn up by receptor mediated process in the ileum..

Question 12

Once the Vitamin B12-IF complex is within the cells of the ileum what occurs?

Answer 12

The complex binds the carrier protein transcolbalmin II where it is then secreted into the blood and taken up by the liver for storage.

Question 13

Where does calcium absorbtion occur and what is required for it?

Answer 13

Absorption occurs mostly in the duodenum and requires the expression of a calcium channel.

Question 14

What is the expression of Calcium channels in the duodenum tied to?

Answer 14

Vitamin D uptake will upregulate vitamin C uptake.

Thus is vitamin D is deficient you will also be deficient in vitamin C.

Question 15

Describe the two forms of iron

Answer 15

Ferrous iron Fe2+
and
Ferric iron Fe3+ (Unsoluble at neutral pH)

Question 16

How can Ferric Iron be made soluble in the intestines?

Answer 16

Vitamin C can reduce ferrc ron to ferrous iron which can then complex with transferrin.

Question 17

How is iron absoarbed?

Answer 17

Ferrous iron is conjucated to transferrin where it can be moved into the intestinal cells.
The iron then enters the blood and complexes to plasma transferin where it will travel to the liver,

Question 18

What transporter takes up ferrous iron?

Answer 18

Divalent cation transporter 1 (DCT1)

Question 19

What is celiac sprue?

Answer 19

Loss of mature villi of the duodenal and jejunal epithelium following ingestion of gluten.
Loss of the villi reduce the surface area and absorption in the intestine.

Question 20

What causes pernicious anemia?

Answer 20

Lack of Vitamin B12 and Folic acid absorbtion (required for DNA synthesis)

Causes megaloblastic anemia!