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DMD 5242 > Carbohydrate Digestion (complete) > Flashcards

Carbohydrate Digestion (complete) Flashcards

1
Q

What is central to all digestion

A

glucose

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2
Q

What is the preferred energy source of the brain

A

glucose

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3
Q

what is the required energy source for the red blood cells

A

glucose

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4
Q

What is an essential energy source for exercising muscles

A

glucose

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5
Q

Glucose is a fundamental precursor to which important compounds

A
  1. Lactose
  2. glycogen
  3. Nucleic Acids
  4. Amino Acids
  5. Steroid hormones
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6
Q

What are is the normal blood glucose range

A

70 - 100 mg/dL

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7
Q

What is it called when your blood glucose is below 70 mg/dL

A

hypoglycemia

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8
Q

what is it called when your blood glucose is above 100 mg/dL

A

hyperglycemia

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9
Q

What is Digestion

A

the enzymatic conversion of polysaccharides and disaccharides to their corresponding monosaccharides

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10
Q

What are the three main types of carbohydrates in the american diet

A
  1. starch
  2. sucrose
  3. lactose
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11
Q

What are typical sources of starches

A

potatoes, rice, corn, wheat

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12
Q

what are typical sources of sucrose

A

table sugar, desserts, fruit

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13
Q

What are typical sources of lactose

A

milk, milk products

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14
Q

What % of daily carbs come from starches

A

60%

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15
Q

what % of daily carbs come from sucrose

A

30%

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16
Q

what % of daily carbs comes from lactose

A

10%

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17
Q

How do you differentiate between D and L isomers of sugars

A

You must find the -OH group that is on they assymetric carbon (the one furthest from the carbonyl carbon)
if it is to the right, then it is a D isomer
if it is to the left, then it is an L isomer

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18
Q

Are all naturally occurring sugars L or D isomers

A

D isomers

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19
Q

sugars of ___ or more carbons usually under cyclization

A

5

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20
Q

what are the two types of isomers created by cyclization of sugars

A

Alpha and Beta isomers

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21
Q

How do you distinguish between alpha and beta isomers of a sugar

A

in the alpha isomer the hydroxyl group of the anomeric carbon will be below the plane of the ring
in the beta isomer the hydroxyl group of the anomeric carbon will be above the plane of the ring

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22
Q

How does cyclization of a monosaccharide occur

A

the hydroxyl group of the fifth carbon attacks the carbonyl carbon, and the oxygen of the fifth carbon becomes attached to the carbonyl carbon

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23
Q

what is the anomeric carbon

A

the carbon that used to be the carbonyl carbon, but then became bonded to the oxygen of the 5th carbon. This is also the carbon used to determine if it is an alpha or beta isomer

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24
Q

besides isomers what is another term used to describe the relationship between the alpha and beta isomers of a monosaccharide

A

they are anomers

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25
Q

what is a pyranose ring

A

ring systems with 5 carbons and an oxygen

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26
Q

what is a furanose ring

A

ring systems with 4 carbons and an oxygen

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27
Q

what is the difference between aldoses and ketoses (types of monosaccharides)

A

aldoses have the carbonyl carbon as Carbon #1

ketoses have the carbonyl carbon as Carbon #2

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28
Q

What is the difference between the anomeric carbons of ketoses and aldoses when they become cyclized

A

ketoses have thier anomeric carbon as carbon #2

aldoses have their anomeric carbon as carbon #1

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29
Q

is glucose a ketose or an aldose

A

an aldose

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30
Q

is fructose a ketose or an aldose

A

a ketose

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31
Q

is galactose a ketose or an aldose

A

an aldose

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32
Q

is lactose a ketose or an aldose

A

an aldose

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33
Q

What is a glycosidic bond

A

C—O—C

an oxygen between two carbons

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34
Q

where do we find glycosidic bonds

A

between monosaccharides in di and polysaccharides

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35
Q

What are the steps of naming glycosidic bonds

A
  1. name the monosaccharide forming the bond with it’s anomeric carbon
  2. state what conformation the anomeric carbon is in (alpha or beta)
  3. state which carbon is the active anomeric carbon (1-6) and state which carbon on the other monosaccharide is participating in the bond
  4. name the second sugar
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36
Q

Give an example of a glycosidic bond

A

glucosyl-alpha(1-4)-glucose

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37
Q

what sugar and which isomer make up all starches

A

alpha-D-glucose

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38
Q

What is amylose

A

an unbranched chain of alpha-d-glucose

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39
Q

What are the bonds involved in amylose

A

only alpha (1–>4) bonds

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40
Q

which end of polysaccharides is the reducing end

A

the end of the polysaccharide with the anomeric carbon exposed (not connected to another monosaccharide by a glycosidic bond)

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41
Q

which end of polysaccharides is the non-reducing end

A

the end of the polysaccharide where the anomeric carbon is not exposed

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42
Q

how many reducing ends does amylose have

A

1

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43
Q

how many non reducing ends does amylose have

A

1

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44
Q

how many reducing ends does amylopectin have

A

1

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45
Q

how many non-reducing ends does amylopectin have

A

many

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46
Q

what is the difference between reducing sugars and non-reducing sugars

A

reducing sugars have an exposed anomeric carbon, non-reducing sugars do not

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47
Q

what is amylopectin

A
  1. a branched starch

2. separate chains of alpha-d-glucose that are linked by alpha 1-6 linkages

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48
Q

How often are the glucoses of amylopectin bound to another chain of alpha-d-glucoses by alpha 1-6 linkages as opposed to being bound to another alpa-d-glucose by an alpha1-4 linkage

A

one of tweny glucoses form alpha 1-6 linkages and create branching

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49
Q

what are the bonds that cause the branching of amylopectin

A

alpha 1-6 glycosidic bonds

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50
Q

what are starches mixtures of

A

amylose and amylopectin

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51
Q

what percentage of polysaccharides in starches are amylopectin, and amylose

A

starches are 85% amylopectin and 15% amylose

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52
Q

What is the only difference between glucose and galactose

A

glucose has it’s 4th hydroxy group down

galactose has it’s 4th hydroxy group up

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53
Q

what is the relation between galactose and glucose

A

they are epimers

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54
Q

what are epimers

A

isomers that differ in orientation at only one carbon

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55
Q

What is glycogen

A

It is the form of carbohydrate storage in animals. branched, and very similar to amylopectin, just slightly more branched

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56
Q

What are the types of bonds in amylose

A

only Alpha 1-4

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57
Q

what are the types of bonds in amylopectin

A

mostly alpha 1-4

some alpha 1-6

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58
Q

what are the types of bonds in glycogen

A

mostly alpha 1-4

some alpha 1-6

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59
Q

how many reducing ends does glycogen have

A

1

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60
Q

how many non reducing ends does glycogen have

A

many

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61
Q

What percent of glycogen bonds are alpha 1-6 as opposed to alpha 1-4 bonds

A

8% are alpha 1-6 bonds (5% in amylopectin)

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62
Q

what is the plant form of carbohydrate storage

A

starch

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63
Q

What is cellulose

A

a linear (unbranched) polysaccharide made up of beta 1-4 linkages

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64
Q

What monosaccharide makes up amylose, amylopectin, glycogen, and cellulose

A

glucose

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65
Q

what is the type of bond between the glucose monosaccharides in cellulose

A

beta 1-4

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66
Q

what is significant about the beta 1-4 bonds in cellulose

A

the human body doesn’t have the enzymes to hydrolize the bond, so the human body can’t digest cellulose

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67
Q

what is hydrolysis of glycosidic bonds

A

the breaking of the glycosidic bonds that uses H2O

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68
Q

how many reducing ends does cellulose have

A

1

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69
Q

how many non reducing ends does cellulose have

A

1

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70
Q

What is sucrose

A

a disaccharide with glucose and fructose as it’s monosaccharides

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71
Q

what is the glycosidic bond between fructose and glucose in sucrose

A

it is a alpha beta 1 - 2 bond

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72
Q

what does the alpha beta 1-2 bond in sucrose refer to

A

the anomeric carbon (#1) of glucose is in the alpha conformation, it is bound to the anomeric carbon (#2) of fructose which is in the beta conformation

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73
Q

what is another name for sucrose

A

table sugar

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74
Q

what are the bonds in sucrose

A

Only one alpha beta 1-2 bond

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75
Q

is sucrose a reducing sugar

A

no

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76
Q

why is sucrose not a reducing sugar

A

because both of the anomeric carbons are participating in a bond and aren’t exposed.

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77
Q

What is lactose

A

a galactose bound to a glucose

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78
Q

what is the bond in lactose

A

a beta 1-4 bond between galactose and glucose

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79
Q

in lactose which end is the reducing sugar

A

the end with glucose (not galactose)

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80
Q

expound upon the bond between galatose and glucose in lactose

A

the anomeric carbon (#1) of galactose is in the beta conformation and it binds to the #4 carbon of the glucose

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81
Q

is lactose a reducing sugar

A

yes

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82
Q

what are the two monosaccharides that make lactose

A

glucose and galactose

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83
Q

what types of organisms (animals and plants) have lactose

A

only mammals

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84
Q

What is trehalose

A

a disaccharide of two glucose molecules

85
Q

what is the bond like between the two glucoses of trehalose

A

it is an alpha alpha 1-1 bond

86
Q

expound upon the alpha alpha 1-1 bond of trehalose

A

the anomeric carbons of the two glucoses (#1 and #1) are both in the alpha confomation and they are bound to each other

87
Q

where can trehalose be found

A

insect blood, mushrooms, and fungi

88
Q

can the bonds in trehalose be digested in humans

A

yes

89
Q

is trehalose a reducing sugar

A

no

90
Q

why is trehalose a non reducing sugar

A

because both of the anomeric carbons are participating in bonds and not exposed

91
Q

What is the family of enzymes responsible for the digestion of disaccharides and polysaccharides

A

the Glycosidases

92
Q

what is another name for the glycosidases

A

glycoside hydrolases

93
Q

what do glycosidases or glycodise hyrdolases do

A

they hydrolize glycosidic bonds

94
Q

What does it mean to hydrolize glycosidic bonds

A

to break glylcosidic bonds apart and release H2O as a product

95
Q

what is the first enzyme to begin to digest cabohydrates

A

salivary alpha amylase

96
Q

what kind of glucosidase is salivary alpha amylase

A

Alpha 1-4 endo glucosidase

97
Q

what does it mean that salivary alpha amylase is a alpha 1-4 endo glucosidase

A

it means that it cleaves alpha 1-4 glycoside bonds, and the endo portion means that it cannot cleave terminal alpha 1-4 bonds.

98
Q

What polysaccharides and disaccharides can salivary alpha amylase digest

A

starches and glycogen (poly)

it cannot digest disaccharides

99
Q

What bonds can’t be cleaved by salivary alpha amylase that are commonly found in poly and disaccharides

A
  1. it can’t cleave terminal alpha 1-4 bonds
  2. it can’t cleave the alpha 1-6 bonds
  3. in can’t cleave the alpha 1-4 bonds that are adjacent to the branch points of amylopectin and glycogen
100
Q

What are the possible products after salivary alpha amylase has began the digestion of carbohydrates

A
  1. maltose
  2. maltoriose
  3. oligosaccharides
  4. alpha dextrin
101
Q

What is maltose

A

a disaccharide with two glucose molecules bound with an alpha 1-4 bond

102
Q

What is maltotriose

A

a trisaccharide with three glucose molecules bound with alpha 1-4 bonds

103
Q

What are oligosaccharides

A

four or more glucose molecules connected with alpha 1-4 linkages

104
Q

what is alpha dextrin

A

four or more glucose molecules (alpha 1-4 linkages) that are linked by a branch point (alpha 1-6 linkage)

105
Q

from what kind of carbohydrates can alpha dextrin be a product of after it has begun to be digested by salivary alpha amylase

A

amylopectin and glycogen

106
Q

what are the most common products formed after salivary alpha amylase begins to digest carbohyrates in the mouth

A

oligosaccharides and alpha-dextrin

107
Q

Why are oligosaccharides and alpha-dextrin the most common products formed by salivary alpha amylase

A

because the salivary alpha amylase only has a few seconds to digest the carbohydrates and doesn’t have enough time to break those down further.

108
Q

what causes salivary alpha amylases to stop digesting the bolus

A

the acidity of the stomach is to strong (too low of pH) for salivary alpha amylase to continue functioning

109
Q

how does the stomach participate in carbohydrate digestion

A

It does not have glycosidases, but it does do acid hydrolysis of sucrose

110
Q

What are the two phases of carbohydrate digestion in the small intestine

A
  1. The luminal phase

2. The membrane phase

111
Q

What are the players in the luminal phase of carbohydrate digestion in the small intestine

A
  1. Intestinal epithelial cells
  2. secretin
  3. pancreas
  4. bicarbonate
  5. cystokinin
  6. Pancreatic salivary amylase
112
Q

What is the function of the intestinal epithelial cells during the luminal phase of carbohydrate digestion

A

they secrete secretin which signals to the pancreas to secrete bicarbonate and this enters the intestines and neutralizes the acids from the stomach so that glycosidases can begin to digest carbohydrates

113
Q

what is the function of secretin

A

it signals to the pancreas to secrete bicarbonate

114
Q

what is the function of bicarbonate

A

it neutralizes the stomach acids in the intestines allowing the pancreatic glycosidases to work

115
Q

what is the function of cystokinin

A

it signals to the pancreas to secrete digestive enzymes, specifically pancreatic alpha amylase for carbohydrate digestion

116
Q

what is the function of pancreatic alpha amylase

A

it continues the digestion of carbohydrates in the intestines

117
Q

what are the carbohydates that pancreatic alpha amylase can digest

A

amylose
amylopectin
glycogen

118
Q

what are the products after pancreatic alpha amylase digests amylose, amylopectin, and glycogen

A
  1. maltose
  2. maltotriose
  3. alpha dextrin (from amylopectin and glycogen)
  4. oligosaccharides (if it doesn’t have the time to fully digest it)
119
Q

How similar is pancreatic alpha amylase to salivary alpha amylase

A

they are the same with the exception of where they are located

120
Q

What bonds can the pancreatic alpha amylase cleave

A

alpha 1-4 bonds between two glucoses, but only interior bonds

121
Q

What bonds aren’t cleavable with pancreatic alpha amylase

A
  1. terminal alpha 1-4 bonds
  2. alpha 1-4 bonds adjacent to branch points
  3. alpha 1-6 bonds
  4. can’t do the bonds of sucrose, lactose, and trehalose
122
Q

What are the players in the membrane phase of carbohydrate digestion in the small intestine

A
  1. Enterocytes
    a. brush border membrane (lumenal membrane)
    b. contalumenal membrane
  2. lactase
  3. trehalase
  4. glucoamylase complex
  5. sucrase-isomaltase complex
123
Q

What are enterocytes

A

intestinal absorptive cells

124
Q

what is the membrane of enterocytes that is facing the lumen (the inside of the small intestine)

A

the lumenal membrane

or the brush border membrane

125
Q

What is the membrane of the enterocytes that is next to the basement membrane and the capillaries

A

the contralumenal membrane

126
Q

What needs to happen in carbohydrate digestion at the enterocytes

A
  1. the carbs and remaining structures need to be broken down into monosaccharides
  2. the monosaccharides need to be carried into the enterocytes
  3. the monosaccharides need to cross the contralumenal membrane into the capillaries
127
Q

What breaks the carbohydrates down into monosaccharides

A

the digestive enzymes embedded into the lumenal membrane

128
Q

What are the enzymes in the lumenal membrane

A

lactase
trehalase
sucrase-isomaltase complex
glucoamylase complex

129
Q

What is the structures of these enzymes that are embedded in the lumenal membrane of enterocytes

A

they have a structural part inside the membrane and a catalytic portion sticking out into the lumen

130
Q

what kind of bonds does lactase cleave

A

beta 1-4 bonds between glucose and galactose (the bonds of lactose)

131
Q

What kind of bonds does trehalase cleave

A

alpha alpha 1-1 bonds between two glucose molecules (the bonds of trehalose)

132
Q

What are the products given off of lactase

A

galactose and glucose

133
Q

what are the products given off of trehalase

A

two glucoses

134
Q

What kinds of bonds does the glucoamylase-complex digest

A

alpha 1-4 bonds (EXO)

meaning that it cleaves terminal alpha 1-4 bonds between glucose

135
Q

from what end does the glucoamylase-complex cleave alpha 1-4 bonds

A

from the non-reducing end

136
Q

What things can the glucoamylase-complex cleave

A
  1. maltose
  2. malotriose
  3. alpha 1-4 bonds adjacent to branch points
137
Q

what can’t the glucoamylase complex cleave

A
  1. alpha 1-6 bonds

2. bonds of sucrose, lactose, and trehalose

138
Q

What kinds of bonds does the sucrase-isomaltase complex cleave

A
  1. alpha beta 1-2 bonds of sucrose (glucose and fructose)
  2. alpha 1-6 bond of alpha-dextrin
  3. alpha 1-4 bonds between glucose molecules (maltose, maltotriose)
139
Q

What carbs can the sucrase-isomaltase complex digest

A

1, sucrose

  1. maltose
  2. maltotriose
  3. isomaltose
140
Q

What is isomaltose

A

two glucose molecules linked alpha 1-6 ( the branch point of amylopectin and glycogen)

141
Q

What are the two enzymes that can cleave maltose and maltotriose

A
  1. glycoamylase complex

2. sucrase-isomaltase complex

142
Q

what are the potential products of sucrase-isomaltase digestion of carbs

A
  1. glucose

2. fructose

143
Q

would we be able to digest carbs if we didn’t have salivary alpha amylase

A

yes (we have pancreatic alpha amylase)

144
Q

what are dietary fibers

A

carbohydrates or carbohydrate derivatives that can’t be digested by our digestive enzymes

145
Q

What are the two different kinds of dietary fibers

A
  1. soluble

2. insoluble

146
Q

what is an example of insoluble fiber

A

cellulose

147
Q

what are examples of soluble fiber

A

pectin and gums

148
Q

What is an important characteristic of soluble fibers

A

they absorb water

149
Q

What happens to the more soluble types of fibers

A

they move down to the colon and are digested by bacteria in the colon

150
Q

What are the products of bacterial digestion of soluble fibers in the colon

A
  1. Gases (CO2, H2, Methane)
  2. Short chain fatty acids (acetic, propryonic, and butyric)
  3. Lactate
151
Q

What are the 5 main benefits of dietary fibers

A
  1. they can bind carcinogens in the colon and take them out in the stool
  2. they can bind bile acids and take them out in the stool, so instead of reabsorbing them like it usually does the body has to remake them from cholesterol. this lowers our cholesterol
  3. they slow the absorption of glucose, preventing the spiking in blood glucose in diabetics
  4. they absorb more water, which makes stool softer, which helps a lot in diverticular disease
  5. they absorb more water so for people with IBS it is helpful in softening the stool as well
152
Q

are monosaccharides polar or non-polar

A

polar

153
Q

What is needed for monosaccharides to cross the lumenal membrane into the enterocytes

A

transport proteins are needed

154
Q

What are the two membranes that monosaccharides have to cross to reach the capillaries

A
  1. lumenal membrane

2. contralumenal membrane

155
Q

What are the two kinds of transporters that assist in transporting monosaccharides across the lumenal and contralumenal membranes

A
  1. SGLT

2. GLUT

156
Q

What are SGLT transporters

A

sodium dependent transporters that use active transport

157
Q

Which SGLT transporter aids in the abosrbtion of monosaccharides

A

SGLT 1

158
Q

What monosaccharides does SGLT-1 transport

A

glucose and galactose

159
Q

What does SGLT-1 do

A

it brings galactose and glucose from the lumen into the enterocyte

160
Q

How does SGLT-1 work

A

sodium goes down it’s own gradient into the cell and brings glucose and galactose into the cell (AGAINST their concentration gradient)

161
Q

Why is it important the SGLT-1 brings glucose and galactose into the enterocyte against their concentration gradients

A

because this means that no matter the concentration of glucose and galactose outside of the cell, it will still be absorbed into the enterocyte

162
Q

What are the GLUT transporters

A

glucose transporters that work by facilitated diffusion

163
Q

What are the GLUT transporters involved in carbohydrate absorption in the gut

A

GLUT 5 and GLUT 2

164
Q

what does GLUT 5 do

A

it brings fructose into the enterocyte

165
Q

can GLUT 5 bring glucose into the enterocyte as well as fructose

A

yes, it can bring glucose into the enterocyte, but it has a much higher affinity to fructose

166
Q

What does GLUT 2 do

A

it transports glucose, galactose, and fructose across the contalumenal membrane into the capillaries

167
Q

Where is GLUT 1 active

A

in red blood cells, blood-brain barrier

168
Q

Where is GLUT 2 active

A

in the liver, pancreatic Beta-cells, contralumenal membrane of intestinal epithelial cells

169
Q

Where is GLUT 3 active

A

in the neurons of the brain

170
Q

where is GLUT 4 active

A

adipose tissue, skeletal muscle, heart muscle (insulin sensitive transporter)

171
Q

Where is GLUT 5 active

A

Intestinal epithelial cells (from lumen into cells), sperm (fructose transporter)

172
Q

Where is SGLT-1

A

Intestinal epithelial cells

173
Q

Where is SGLT-2

A

Kidney (tubular epithelial cells)

174
Q

What does the Glycemic Index measure

A

it measures how quickly you see a rise in blood glucose after food is consumed.

175
Q

What are things with a high glycemic index

A

things that are quickly digested, which leads to a quick spike in blood glucose

176
Q

is it better to eat things of high glycemic index or a low glycemix index

A

a low glycemic index

177
Q

What is the flaw with the Glycemic index

A

it doesn’t figure in the serving size

178
Q

What Is Glycemic load

A

The glycemic index multiplied by the standard serving of that food

179
Q

What causes lactose intolerance

A

a lactase deficiency

180
Q

What happens when you can’t properly digest lactose

A
  1. lactose draws in water, increasing fluid load
  2. in the colon we get gas, short chain fatty acids, and lactic acid from bacterial digestion of lactose
  3. lactic acid draws in more water, greatly increasing fluid load
  4. bloating, fullness, cramps, and pain are symptoms of the pressure in the gut
  5. distension of the walls leads to increased peristalsis
  6. peristalsis increase and increased water = diarrhea
  7. quick passing of things through the gut leads to decreased absorption of nutrients
  8. Dehydration, loss of electrolytes
  9. all this leads to malnutrition
181
Q

What are the 5 classifications of lactose intolernace

A
  1. congenital lactase deficiency in infants and children
  2. temporary lactase deficiency in premature infants
  3. Acquired isolated lactase deficiency
  4. Lactase deficiency secondary to intestinal diseases
  5. Lactase deficiency secondary to insufficient mucosal contact time
182
Q

What is congenital lactase deficiency in infants and children

A

Children born with low levels of lactase

183
Q

what is temporary lactase deficiency in premature infants

A

Children that haven’t yet developped enough lactase

184
Q

What is acquired isolated lactase deficiency

A

AKA late onset lactase deficiency or adult hypolactasia

With age our lactase levels decrease, especially in cultures that don’t consume much lactose

185
Q

What is lactase deficiency secondary to intestinal disease

A

AKA secondary lactase deficiency

damage to intestinal mucosa that leads to decreased lactase ability

186
Q

What is lactase deficiency secondary to insufficient mucosal contact time

A

if stuff isn’t in the intestine long enough then it can’t digest the lactose enough

187
Q

How do you diagnose lactose intolerance

A

Easy way = take lactose away see if symptoms dissapear. if they do give it back, see if the symptoms come back
Other way = test the amount of hydrogen in their breath after giving them a test meal with lactose

188
Q

what is the normal glucose tolerance curve like

A

blood glucose reaches a peak between 30-60 minutes after consumption, then it returns to its fasting level in about two hours

189
Q

What is the difference between sucrose and sucralose (the artificial sweetener)

A

sucralose is a alpha beta 1-2 linkage between galactose and fructose, (not glucose and fructose like sucrose) this makes it indigestable

190
Q

What can digest maltose

A

sucrase-isomaltase complex

glucoamylase

191
Q

what can digest maltotriose

A

sucrase-isomaltase complex

glucoamylase

192
Q

what can digest isomaltose

A

sucrase-isomaltase

193
Q

what can digest lactose

A

lactase

194
Q

what can digest trehalose

A

trehalase

195
Q

what can digest sucrose

A

sucrase-isomerase complex

196
Q

how does fiber help with diabetes

A

it slows the absorption of glucose into the blood

197
Q

Which one of the following compounds is NOT produced from dietary starch by α-amylase?

	a. maltose
	b. maltotriose
	c. fructose
	d. oligosaccharides
	e. α-dextrins
A

fructose

198
Q

After digestion of a piece of cake that contains flour, milk and sucrose as its primary ingredients, the major carbohydrate products entering the blood are:

	a. glucose
	b. fructose and glucose
	c. galactose and glucose
	d. glucose, fructose, and galactose
A

glucose, fructose, and galactose

199
Q

A patient has a genetic defect that causes intestinal epithelial cells to produce disaccharidases of much lower activity than normal. Compared to a normal person, after eating cake (flour, milk, sucrose) this patient will have higher levels of:

	a. maltose, sucrose, and lactose in the stool
	b. starch in the stool
	c. galactose and fructose in the blood
	d. lactose in the blood
	e. sucrose in the blood
A

maltose, sucrose and lactose in the stool

200
Q

Which of the following disaccharides cannot be digested by the sucrase-isomaltase complex?

a. glucose α-1,4 glucose
b. glucose α-1,6 glucose
c. glucose α,α-1,1 glucose
d. glucose α,β-1,2 fructose

A

glucose alpha alpha-1,1 glucose

201
Q

Dietary fiber refers to carbohydrates or carbohydrate derivatives of plant origin that are not hydrolyzed by human digestive enzymes. Which of the following statements about soluble fiber is correct?

a. Soluble fiber accelerates the rate of absorption of glucose from the gut into intestinal epithelial cells.
b. Soluble fiber is converted by intestinal bacteria to short chain fatty acids, lactic acid, and gas (CO2, CH4, and H2).
c. Soluble fiber is detrimental to patients with diverticular disease because it causes increased pressure on the colonic wall.
d. When consumed in large quantities, soluble fiber is associated with an increased incidence of colon cancer.
e. Soluble fiber is thought to increase blood cholesterol levels.

A

b. Soluble fiber is converted by intestinal bacteria to short chain fatty acids, lactic acid, and gas (CO2, CH4, and H2).

202
Q

Galactose is transported across the brush border (luminal) membrane of the intestinal epithelial cells with the aid of:

a. SGLT-1
b. GLUT-1
c. GLUT-2
d. GLUT-4
e. GLUT-5

A

SGLT-1

203
Q

. An infant shows symptoms of abdominal fullness, bowel cramps, and diarrhea when fed food sweetened with sucrose. A hydrogen analysis of his exhaled breath showed a 40-fold increase in the production of H2 an hour after consuming 40 g of sucrose dissolved in water. Consumption of a like amount of fructose showed a normal production of H2. The child most likely suffers from:

a. a GLUT-5 deficiency
b. a GLUT-2 deficiency
c. an α-amylase deficiency
d. a sucrase deficiency
e. a lactase deficiency

A

a sucrase deficiency

204
Q
  1. Drug X, a potent inhibitor of the Na+-dependent monosaccharides cotransport system, is administered to a patient. Which of the following monosaccharides would the patient have difficulty in absorbing into intestinal epithelial cells?

a. glucose
b. galactose
c. fructose
d. A and B are correct.
e. A, B and C are correct.

A

A and B are correct

205
Q
  1. A patient is suspected of having a lactase deficiency. Lactose (75 g) dissolved in water was administered orally after an overnight fast and the following blood glucose results were obtained:
Time (min)	Blood Glucose (mg/dl)
0	                             85
30	                             110
60	                             140
90	                             115
120	                             85
These results indicate:

a. normal lactase activity.
b. lactase deficiency.

A

normal lactase activity

206
Q
  1. Chronic use of dairy products by individuals with a lactase deficiency may result in:

a. diarrhea
b. rapid intestinal transit time.
c. malabsorption of drugs.
d. A and B are correct.
e. A, B, and C are correct

A

A, B, and C are correct

207
Q
  1. Which of the following statements are correct?

a. Not all carbohydrates contained in food are digested at the same rate.
b. The glycemic index refers to the effect of 50 g of carbohydrate in a particular food on blood glucose compared to 50 g of glucose.
c. The higher of glycemic index of a particular food, the slower the rise of blood glucose after the food is consumed.
d. A and B are correct.
e. A, B, and C are correct.

A

A and B are correct

208
Q

What can inflammation and damage to the gut cause, and how does that affect abosrption

A

it can cause gaps or tears in the intestine

this can result in absorption of things that aren’t normally absorbed. (disaccharides)

209
Q

Which membrane carbohydrate enzyme is the most easily damaged, and the slowest to recover

A

lactase

DMD 5242 (10 decks)

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