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S&F 4 test 1 > Green - Digestion And Absorption Of Carbs And Proteins > Flashcards

Green - Digestion And Absorption Of Carbs And Proteins Flashcards

1
Q

Enzymes that cleave starches

A

Alpha-amylases

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2
Q

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

A

Borborygmi

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3
Q

Peptide produced by the liver that regulates iron transport from enterocytes

A

Hepcidin

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4
Q

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

A

SGLT-1

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5
Q

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

A

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

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6
Q

Fructose is absorbed exclusively by?

A

Facilitated diffusion

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7
Q

Explain the mechanism of lactose intolerance

A

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

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8
Q

What is sucrase-isomaltase deficiency

A

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

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9
Q

What happens in glucose/galactose malabsorption

A

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

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10
Q

What transporter is genetically missing in glucose/galactose malabsorption

A

SGLT1

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11
Q

What are the sources for proteins for absorption?

A

Exogenous - dietary

Endogenous - proteins from cells shed into GI lumen

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12
Q

What does the class of peptidases called endopeptidases do?

A

They hydrolyze the interior peptide bond

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13
Q

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

A

Trypsin

Chymotrypsin

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

Gastric peptsin

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14
Q

What is the mechanism that exopeptidases use to digest proteins

A

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

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15
Q

What are some exopeptidases?

A

Carboxypeptidase A

Carboxypeptidase. B

Secreted from pancreas in inactive form

Trypsin activates them

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16
Q

Starches are initially digested to ?

A

Maltose

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17
Q

How is fructose transported?

A

Facilitated diffusion

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18
Q

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

A

Na-dependent co-transport

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19
Q

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

A

More efficient

Faster

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20
Q

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

A

Di- and tri- peptides

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21
Q

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

A

H+ dependent co-transporter

Peptide transporter 1 (PEPT1)

22
Q

________ affects uptake of Basic AA’s

A

Cystinuria

23
Q

Cystinuria affects the uptake of ______ AA’s

A

Basic

24
Q

_______ affects uptake of neutral AA’s

A

Hartnup’s disease

25
Q

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

A

Neutral

26
Q

Familial iminioglycinuria affects the uptake of what amino acids?

A

Proline

Hydroxyproline

27
Q

Most easily absorbed form of iron is?

A

Heme iron

28
Q

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

A

Thru receptor mediated endocytosis

Or

Transport protein HCP1

29
Q

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

A

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

30
Q

What are the 2 forms of dietary free iron?

A

Ferrous (2+)

Ferric (3+)

31
Q

What type of dietary free iron is more readily abosrbed?

A

Ferrous (Fe2+)

32
Q

What type of free dietary iron is most common?

A

Ferric (Fe3+)

This form is insoluble and can precipitate

33
Q

What do ascorbic acid and citric acid do to iron?

A

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

34
Q

What is duodenal cytochrome b?

A

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

35
Q

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

A

The DMT1 transporter

36
Q

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

A

Ferroportin

37
Q

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

A

Ferroportin, along with ferrohephaestin convert ferrous to ferric iron

38
Q

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 _______

A

Hepcidin

39
Q

How does hepcidin regulate entry of iron into plasma?

A

By binding directly to ferroportin

40
Q

What is the mechanism of action for the liver protein hepcidin

A

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]

41
Q

Low iron levels will have ___ hepcidin levels

A

Low

42
Q

When iron levels are in excess, liver secretes ______ hepcidin

A

More

43
Q

Most prevalent nutrient deficiency and most common cause of anemia

A

Iron deficiency

44
Q

Explain hereditary hemochromatosis

A

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

45
Q

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

A

Transcellular

Paracellular

46
Q

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

A

Restricted diffusion thru channels

Na-Glucose, Na-AA cotransport

Na-Cl cotransport

Na-H exchange

47
Q

How is Na+ absorbed in the colon?

A

Na- restricted diffusion channels

48
Q

How is Na absorbed in the ileum?

A

Na-AA, Na-Glucose cotransport

Na-H exchange

Na-Cl cotransport

49
Q

How is Na absorbed in the jejunum?

A

Na-Gluc Na-AA cotransport

Na-H exchange

50
Q

How is Na+ absorbed in the duodenum?

A

Mostly Na-Gluc and Na-AA cotransport

And Na-H exchange

51
Q

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

A

Diffusion thru paracellular route w/ the elctrochemical gradient established by Na+

In cotransport w/ Na+ and K+

In exchange for HCO3-

S&F 4 test 1 (22 decks)

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