Digestion and absorption

Question 1

What is the site of B12 absorption?

Answer 1

Ileum

Question 2

What are the cells that produce intrinsic factor?

Answer 2

Parietal cells of the stomach

Question 3

Are oligosaccharide or polysaccharides absorbed directly?

Answer 3

No–digested to monosaccharides first

Question 4

Where is the first primary site of polysaccharide digestion? What is the enzyme utilized here?

Answer 4

Lumen of the intestine

alpha-amylase

Question 5

What stimulates the release of alpha-amylase? Where does the enzyme come from?

Answer 5

Ach and CCK

Pancreas

Question 6

Where are the lactase, maltase, and isomaltase enzymes found?

Answer 6

On the brush border of the intestines

Question 7

What are the glucose transporters utilized in the intestine?

Answer 7

Luminal side: SLGT1, GLUT5

Intracellular side: GLUT2

Question 8

SGLT1 can move what across the membrane?

Answer 8

Na, Glu, Glc.

Question 9

What is the substrate for GLUT5?

Answer 9

Fructose

Question 10

Where does protein digestion begin? What is the enzyme utilized here? Where does this enzyme from from?

Answer 10

Stomach

Pepsin from chief cells

Question 11

What is the function of gastrin?

Answer 11

Promotes acid secretion, and delays gastric emptying

Question 12

What are the enzymes in the intestines that digest peptides? Where do these come from? What causes their release?

Answer 12

Trypsin–pancreas in response to CCK

Brush border peptidases

Question 13

Are oligopeptide able to be absorbed, or do they need to be broken down fully to amino acids?

Answer 13

Can absorb oligopeptides

Question 14

What is the transporter that can move small oligopeptides across the apical membrane? What is cotransported?

Answer 14

PEP1, uses H ions co transport

Question 15

What is the transporter that can move amino acids across the apical membrane? What is cotransported?

Answer 15

B transporter

Na

Question 16

Where do lipids begin to be digested? What are the enzymes utilized here?

Answer 16

Lumen of the stomach

Lingual lipase
Gastric lipase
Emulsification

Question 17

What are the enzymes that digest lipids in the lumen of the duodenum?

Answer 17

Pancreatic lipase
Co-lipase
Emulsification
(Bile)

Question 18

What inactivates gastric lipases?

Answer 18

pancreatic proteases and alkaline conditions

Question 19

What is the primary site of lipid digestion?

Answer 19

Lumen of the duodenum

Question 20

What is the cell types that responds to FAs in the duodenum? What does it release?

Answer 20

I cells, CCK

Question 21

What is the function of colipase?

Answer 21

Regulatory protein that anchors lipase to fatty droplets—IT HAS NO ENZYMATIC ACTIVITY

Question 22

What are the fat soluble vitamins? A defect in what leads to a deficiency?

Answer 22

A, D, E, K

Reduce bile synthesis or secretion

Question 23

What is the transporter for cholesterol and FAs?

Answer 23

NPC1L1

Question 24

What are chylomicrons?

Answer 24

MIxture of lipids in intestinal epithelial cells

Question 25

What do chylomicrons combine with to be transported through the blood?

Answer 25

Lipoproteins

Question 26

Where is the intrinsic factor receptor expressed?

Answer 26

Ileum

Question 27

What is the protein that transports B12 in the body?

Answer 27

transcobalamin

Question 28

Where is B12 stored? Secreted?

Answer 28

Liver and secreted in the bile

Question 29

What happens to parietal cells as we age? Problem with this?

Answer 29

Less of them = less IF = less B12

Question 30

What is the cause of pernicious anemia?

Answer 30

Several important pathologies are related to either an actual or a functional vitamin B12 deficiency. Actual deficiency refers to a lack of vitamin B12 in the diet whereas functional deficiency refers to an inability to absorb or otherwise metabolize the vitamin.

Question 31

What regulates the expression of the Ca transporter in the intestines?

Answer 31

Vit D

Question 32

Lactose intolerance is due to what? What are the symptoms that this causes?

Answer 32

Lactase deficiency in the lumen of the intestines Osmotic diarrhea--bacterial gas production

Question 33

Lactose = what two monomers?

Answer 33

Glucose + galactose

Question 34

Why does gastroparesis lead to poor glycemic control?

Answer 34

Irregular dumping of food into the intestines, causing inefficient absorption. This can change the amount of medication absorbed.

Question 35

What is the role of folic acid?

Answer 35

Needed for DNA synthesis--thus will be upregulated if there is less B12, but no good

Question 36

What transporter is utilized to transport glu, glc, and fructose across the basolateral cell membrane, into the interstitium?

Answer 36

GLUT-2

Question 37

What is the transporter that absorbs cholesterol?

Answer 37

Neimann Pick C1-like1 (NPC1L1)

Question 38

What is the importance of folic acid and B12? What is the primary symptom of a folate deficiency?

Answer 38

Used in DNA synthesis and cell division Anemia d/t loss of RBC production

Question 39

Colbalamin = ?

Answer 39

Vit B12

Question 40

Why is ferric ion not absorbed from the intestines?

Answer 40

It precipitates out at pHs above 3

Question 41

What is the vitamin that reduces Fe 3+ to Fe2+?

Answer 41

C

Question 42

What is the protein carrier of Fe?

Answer 42

Transferrin

Question 43

What is the transporter that absorbs Fe from the intestines?

Answer 43

divalent cation transporter 1 (DCT-1)