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GI > Digestion and Absorption: Carbs, Proteins, Nucleotides, and Lipids > Flashcards

Digestion and Absorption: Carbs, Proteins, Nucleotides, and Lipids Flashcards

1
Q

What is the length of the duodenum and jejuum combined?

A

3 meters

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2
Q

Cause a 5x increase in surface area of small intestine

A

Valvulae conniventes

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3
Q

Cause a 10x increase in surface area of small intestine

A

Villi

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4
Q

Cause a 20x increase in surface area of small intestine

A

Microvilli

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5
Q

The entire small intestine absorbs carbohydrates, proteins, and lipids, but absorption is greatest in the

A

Duodenum (then jejunum and then ileum)

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6
Q

What is a mineral absorbed in the duodenum

A

Iron (as Fe2+)

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7
Q

Folate is a vitamin absorbed in the

A

Small intestine

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8
Q

Absorbed in the terminal ileum along with bile salts

-requires intrinsic factor

A

B12

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9
Q

Total sugars on a food label is referring to

A

Sucrose, lactose, glucose, and fructose

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10
Q

Total carbohydrates minus total sugars and dietary fiber gives you

A

Complex carbohydrates like starch or sugar alcohol

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11
Q

Of the digestible carbohydrates

  1. ) 50% =
  2. ) 40% =
  3. ) 10% =
A
  1. ) Polysaccharides (starch and glycogen)
  2. ) Disaccharides (Sucrose and lactose)
  3. ) Monosaccharides (Glucose and fructose)
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12
Q

The small intestine can only absorb

A

Monosaccharides

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13
Q

Can not absorb monosaccharides

A

Colon

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14
Q

Can not be digested

A

Dietary fiber

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15
Q

Important sources of starch include

A

Corn, potato, and rice

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16
Q

Exists in the form of granules, each of which consist of several million amylopectin molecules together with an even larger number of amylose molecules

A

Starch

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17
Q

Glycogen from animals is a more highly branched form of

A

Amylopectin

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18
Q

In the mouth, starch is attacked by salivary

A

α-amylase

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19
Q

The optimal pH for salivary α-amylase is

A

7 (i.e. it is inactivated in the stomach)

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20
Q

In the duodenum, the acted polysaccharides are then acted on by

A

Pancreatic α-amylase

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21
Q

The main enzyme that breaks the α-1,4 linkage

A

Glucoamylase

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22
Q

Also have activity in breaking the α-1,4 linkage, even though their names suggest otherwise

A

Sucrase and isomaltase

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23
Q

Glucoamylase removes one glucose from the α-limit dextrin formed by

A

Amylase

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24
Q

Then isomaltase acts as the only enzyme that can break the

A

α-1,6 linkage

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25
Q

A More Alkaline Environment in the Duodenum is Required for function of

A

Pancreatic enzymes

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26
Q

Brush border digestion of sucrose and lactose results in glucose and galactose. The uptake of glucose and galactose is then dependent on

A

SGLT-1

27
Q

Uptake of glucose and galactose is then dependent on sodiumglucose cotransporter-1 (SGLT-1) and driven secondarily by the low intracellular sodium concentration established by the

A

Basolateral Na+/K+ ATPase

28
Q

Specifically inhibit glucose reabsorption in the kidney tubule

A

SGLT2 inhibitors

29
Q

The only diabetes-specific drug class that has been show to reduce CV morbidity and death

A

Gliflozins

30
Q

At about age 5, normal lactase expression in the small intestine is suppressed by the

A

MCM6 gene

31
Q

This results in about a 70% world-wide prevalence of

A

Lactose intolerance

32
Q

Has allowed for the continued consumption of milk and milk products in the other 30% of the worlds population

A

MCM6 mutation

33
Q

To prevent autodigestion, gastric and pancreatic proteases are secreted as

A

Proenzymes

34
Q

Secrete pepsinogen, which is activated to pepsin after exposure to HCL

A

Gastric Chief Cells

35
Q

Peptides in the stomach stimulate gastrin secretion –> gastric acid secretion increases –> increased

A

Protein digestion

36
Q

Because pepsin has a pH optimum around 2.0, it is inactivated in the

A

Duodenum (pH = 6)

37
Q

In infants IgA antibodies in maternal colostrum enter the circulation of the infant from the intestine, providing

A

Passive immunity against infection

38
Q

Tri- and dipeptides and amino acids can be absorbed from the

A

GI tract

39
Q

Causes secretion of pancreatic proenzymes

-Stimulated by peptides in the duodenum

A

CCK

40
Q

Trypsinogen is cleaved to trypsin by the enzyme

A

Enterokinase

41
Q

Amplifies its own activation leading to activation of the remaining proteolytic enzymes from the exocrine pancreas

A

Trypsin

42
Q

Peptides are absorbed together with a proton supplied by an apical

A

Sodium/Hydrogen exchanger (NHE)

43
Q

Peptides are absorbed together with a proton supplied by an apical sodium/hydrogen exchanger (NHE) using

A

Peptide transporter 1 (PepT1)

44
Q

Absorbed peptides are digested by cytosolic proteases, and amino acids are transported into the bloodstream at the

A

Basolateral membrane

45
Q

Some amino acids are absorbed directly from the lumen via specific

A

Transporters

46
Q

Made in the exocrine pancreas and secreted into the duodenum via the pancreatic juice

A

RNAse and DNAse

47
Q

At the brush border, phosphatase and nucleosidase convert nucleotides to

A

Pentose sugar, nitrogenous base, and phosphate

48
Q

Pentose, nitrogenous base and phosphate are absorbed in the

A

Duodenum and Jejunum

49
Q

These products enter the blood capillaries of the intestinal villi and travel to the

-For further metabolism

A

Liver

50
Q

A gastric acid lipase is responsible for about

-activated in the duodenum

A

15% of fat digestion

51
Q

Fatty acids enter the duodenum, triggering the release of

A

CCK

52
Q

Contracts the gallbladder and relaxes the sphincter of Oddi resulting in secretion of bile and stimulation of pancreatic enzyme secretion

A

CCK

53
Q

Emulsify fat and increase micelle formation

A

Bile Acids

54
Q

Further digest TAG (90% of fat in the diet)

A

Pancreatic lipase and Colipase

55
Q

Need the higher pH in the duodenum (pH = 6) to act

A

Pancreatic lipase and colipase

56
Q

Packaged into chylomicrons and travel in thoracic duct to the venous circulation

A

TAG and Cholesterol

57
Q

Produced in the colon and absorbed from it

A

Short-chain fatty acids (acetate, propionate, butyrate)

58
Q

Formed by the action of colonic bacteria on complex carbohydrates, and resistant starches

A

Short-chain fatty acids (acetate, propionate, butyrate)

59
Q

Synthesized in the intestine, travels in thoracic duct to the L subclavian vein, then to the liver

A

Chylomicron

60
Q

The apolipoprotein of the chylomicrons

A

ApoB-48

61
Q

Carry TAG, phospholipid, CE, and fat soluble vitamins (ADEK)

A

Chylomicrons

62
Q

Transfers an acyl CoA residue to cholesterol forming a cholesterol ester (CE)

A

ACAT

63
Q

Most of the lipid in the diet is in the form of

A

TAGs

GI (59 decks)

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