Green - Digestion And Absorption Of Carbs And Proteins

Question 1

Enzymes that cleave starches

Answer 1

Alpha-amylases

Question 2

Rumbling or gurgling noise produced by the movement of gas thru the intestines

Answer 2

Borborygmi

Question 3

Peptide produced by the liver that regulates iron transport from enterocytes

Answer 3

Hepcidin

Question 4

Glucose and galactose absorbed into enterocytes by common Na-Dependent active transport system _____

Answer 4

SGLT-1

Question 5

Why can your body use an Na cotransporter to move glucose and galactose into the enterocytes?

Answer 5

The intracellularNa is kept low by a Na-K ATPase, making a gradient for absorption

Question 6

Fructose is absorbed exclusively by?

Answer 6

Facilitated diffusion

Question 7

Explain the mechanism of lactose intolerance

Answer 7

Insufficient lactase to breakdown and absorb lactose. Lactose remains in GI tract. Water stays there with it (diarrhea)

This lactose is then digested by bacteria —> gas, distention, borborygmi, diarrhea

Question 8

What is sucrase-isomaltase deficiency

Answer 8

Sucrose-isomaltase deficiency is an inherited disorder in which the body cannot digest sucrose and isomaltase

Question 9

What happens in glucose/galactose malabsorption

Answer 9

There is a genetic defect in SGLT1, which absorbs both glucose and galactose. This means you can no longer absorb either of these

Question 10

What transporter is genetically missing in glucose/galactose malabsorption

Answer 10

SGLT1

Question 11

What are the sources for proteins for absorption?

Answer 11

Exogenous - dietary

Endogenous - proteins from cells shed into GI lumen

Question 12

What does the class of peptidases called endopeptidases do?

Answer 12

They hydrolyze the interior peptide bond

Question 13

Endopeptidases hydrolyze the interior peptide bonds of proteins. What are the endopeptidases we use

Answer 13

Trypsin

Chymotrypsin

Elastase. (First 3 all pancreatic enzymes, secreted inactive)

Gastric peptsin

Question 14

What is the mechanism that exopeptidases use to digest proteins

Answer 14

They cleave one AA at a time from the C terminus of peptides and proteins

Question 15

What are some exopeptidases?

Answer 15

Carboxypeptidase A

Carboxypeptidase. B

Secreted from pancreas in inactive form

Trypsin activates them

Question 16

Starches are initially digested to ?

Answer 16

Maltose

Question 17

How is fructose transported?

Answer 17

Facilitated diffusion

Question 18

Most AA’s are absorbed into enterocytes by -__-_______

Answer 18

Na-dependent co-transport

Question 19

The transport of Dipeptides and tripeptides is _____________ than for amino acids; using H-dependent co-transporter peptide protein 1 (PEPT1)

Answer 19

More efficient

Faster

Question 20

The majority of protein absorbed after a meal is in form of ________

Answer 20

Di- and tri- peptides

Question 21

What transports di and tri peptides from the lumen to the enterocytes?

Answer 21

H+ dependent co-transporter

Peptide transporter 1 (PEPT1)

Question 22

________ affects uptake of Basic AA’s

Answer 22

Cystinuria

Question 23

Cystinuria affects the uptake of ______ AA’s

Answer 23

Basic

Question 24

_______ affects uptake of neutral AA’s

Answer 24

Hartnup’s disease

Question 25

Hartnup’s disease affects the uptake of _______ AA’s

Answer 25

Neutral

Question 26

Familial iminioglycinuria affects the uptake of what amino acids?

Answer 26

Proline Hydroxyproline

Question 27

Most easily absorbed form of iron is?

Answer 27

Heme iron

Question 28

What are the 2 ways that heme-bound iron is taken up into enterocytes?

Answer 28

Thru receptor mediated endocytosis Or Transport protein HCP1

Question 29

What happens to heme that is absorbed once it is in the enterocytic cytoplasm

Answer 29

It is broken down by heme oxygenase to release the free iron

Question 30

What are the 2 forms of dietary free iron?

Answer 30

Ferrous (2+) Ferric (3+)

Question 31

What type of dietary free iron is more readily abosrbed?

Answer 31

Ferrous (Fe2+)

Question 32

What type of free dietary iron is most common?

Answer 32

Ferric (Fe3+) This form is insoluble and can precipitate

Question 33

What do ascorbic acid and citric acid do to iron?

Answer 33

Promote absorption by forming soluble complexes w/ iron and reducing ferric iron to ferrous iron

Question 34

What is duodenal cytochrome b?

Answer 34

Dcyt b is a brush border enzyme in the duodenum that reduces ferric iron to ferrous iron, making it more absorbable.

Question 35

What transporter moves ferrous (Fe2+) iron from the brush border lumen into the enterocyte?

Answer 35

The DMT1 transporter

Question 36

What does the ferrous iron go thru to get from enterocyte to blood stream?

Answer 36

Ferroportin

Question 37

What happens to ferrous iron as it passes from the enterocyte thru the ferroportin into the bloodstream?

Answer 37

Ferroportin, along with ferrohephaestin convert ferrous to ferric iron

Question 38

Body has no mech for removing excess iron, so absorption is regulated. This is based on body requirements. Much of this regulated orchestrated by liver derived peptide _______

Answer 38

Hepcidin

Question 39

How does hepcidin regulate entry of iron into plasma?

Answer 39

By binding directly to ferroportin

Question 40

What is the mechanism of action for the liver protein hepcidin

Answer 40

It regulates the entry of iron into the blood by binding directly to ferroportin. This causes the internalization of dedragation of ferroportin, cellular iron export and decreasing [plasma iron]

Question 41

Low iron levels will have ___ hepcidin levels

Answer 41

Low

Question 42

When iron levels are in excess, liver secretes ______ hepcidin

Answer 42

More

Question 43

Most prevalent nutrient deficiency and most common cause of anemia

Answer 43

Iron deficiency

Question 44

Explain hereditary hemochromatosis

Answer 44

Hereditary hemochromatosis is the most common genetic disorder in US. Characterized by defect in HFE gene which causes hepcidin levels to drop, leading to excess iron collection in liver. Leads to cirrhosis and eventually liver cancer Also can damage pancreas, leading to diabetes Contributes to CAD Treat by periodically removing blood

Question 45

What are the two routes that electrolytes and H2O cross the intestinal epithelial cells?

Answer 45

Transcellular Paracellular

Question 46

What are the 4 ways which Na crosses the intestinal epithelium?

Answer 46

Restricted diffusion thru channels Na-Glucose, Na-AA cotransport Na-Cl cotransport Na-H exchange

Question 47

How is Na+ absorbed in the colon?

Answer 47

Na- restricted diffusion channels

Question 48

How is Na absorbed in the ileum?

Answer 48

Na-AA, Na-Glucose cotransport Na-H exchange Na-Cl cotransport

Question 49

How is Na absorbed in the jejunum?

Answer 49

Na-Gluc Na-AA cotransport Na-H exchange

Question 50

How is Na+ absorbed in the duodenum?

Answer 50

Mostly Na-Gluc and Na-AA cotransport And Na-H exchange

Question 51

What are the 3 methods for Cl- absorption in the GI tract?

Answer 51

Diffusion thru paracellular route w/ the elctrochemical gradient established by Na+ In cotransport w/ Na+ and K+ In exchange for HCO3-