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GI Tract Biochem > Digestion and Absorption of Nutrients > Flashcards

Digestion and Absorption of Nutrients Flashcards

1
Q

The major routes of absorption for glucose are:

A

SGLT-1, GLUT-5, and GLUT-2

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2
Q

Collectively the microvillous regions constitute the ___________.

A

Brush border

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3
Q

Final breakdown of carbohydrates, proteins and fats occur in:

A

Small Intestine

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4
Q

Is most commonly caused by deficiencies in carbohydrate-splitting enzymes in the intestinal brush border

A

Diarrhea caused by the poor assimilation of dietary carbohydrates

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5
Q

Peptide bonds are hydrolyzed by: ____________

A

Peptidases

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6
Q

Cleaves proteins at hydrophobic amino acids

A

Elastase

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7
Q

Luminal digestion of starch begins in mouth with the action of: ______________

A

Salivary α-amylase

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8
Q

Cellulase

A

Enzyme not present in human GI tract that is capable of digest the B-glucose bonds of cellulose and hemicellulose

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9
Q

Sercete enzymes in pancreas

A

Exocrine cells

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10
Q

Most nutrients are absorbed in: _____________

A

Ileum

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11
Q

High-molecular-weight polysaccharide similar to amylopectin in molecular structure but having considerably more 1,6- linkages

A

Glycogen

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12
Q

Is nonexistent because pancreatic amylase is secreted in tremendous excess.

A

Maldigestion of starch in humans

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13
Q

GI Physiology can be affected by:

A

Starvation, irradiation, and the loss of a portion of the bowel.

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14
Q

Exits the basolateral membrane by another facilitated diffusion, involving the GLUT-2 transporter.

A

Fructose

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15
Q

Acid secretion is stimulated by __________ and accompanied by morphologic changes in __________.

A

Extracellular Signals, Parietal Cells

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16
Q

Is the most frequently observed congenital disaccharidase deficiency and can exist in the absence of any other intestinal malfunction.

A

Lactase Deficiency

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17
Q

Solubilization is aided by the release of bile salts from the gallbladder, this process is stimulated by:

A

Cholecystokinin

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18
Q

The H + transported by the proton pump are supplied by:

A

Carbonic Anhydrase

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19
Q

Glucose and chemically related sugars are absorbed by: ______________

A

Na+ dependent secondary active transport process

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20
Q

Similar to amylose but in addition to α-1,4- linkages there is a α-1,6-linkage for every 20 to 30 glucose units.

A

Amylopectin

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21
Q

Final digestion of oligopeptides and dipeptides is carried out in the small intestine by:

A

Endopeptidases, Dipeptidases, and Aminopeptidases

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22
Q

Polysaccharides and oligosaccharides are absorbed as:

A

Polysaccharides

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23
Q

Who secrete enzyme in mouth?

A

Glandular Cells

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24
Q

Cimetidine or Ranitidine

A

H2 antagonist (prevent histamine release)

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25
Q

Cleaves proteins at aromatic amino acids

A

Chymotrypsin

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26
Q

The only products of sugar digestion are:

A

Glucose, Galactose, and Fructose

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27
Q

What happened to di and tripeptides within the enterocytes?

A

Are hydrolyzed to their constituent amino acids

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28
Q

Bile salts and pancreatic enzymes act on the lipid emulsion that take place in the:

A

Duodenum

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29
Q

Describe 2nd step of digestion

A

Secretion of enzymes that break down macromolecules to a mixture of oligomers, dimers, and monomers.

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30
Q

All lactose is broken down into glucose and galactose by

A

Lactase

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31
Q

Produces mainly 2-monoacyl glycerols (2- MAG), which are absorbed into enterocytes.

A

Pancreatic Lipase

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32
Q

Is approximately 50% of the calories ingested

A

Daily Intake of Carbs

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33
Q

In these cases the patients show no symptoms when they are fed fructose

A

Intolerance to glucose and galactose

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34
Q

Are associated with inflammation in the small bowel mucosa. These conditions are often attended by brush border enzyme deficiencies.

A

Celiac disease, certain bacterial infections, and some protozoan and helminth infections

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35
Q

Break down large polypeptides into smaller oligopeptides

A

Endopeptidases

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36
Q

Protects the stomach from the effects of the strong acid.

A

Alkaline Mucus secreted by epithelial cells

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37
Q

Who secrete enzymes in stomach?

A

Chief Cells

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38
Q

Covalently modifies cysteine residues located in the extracytoplasmic domain of the α- subunit and inhibits the proton pump, blocking H secretion

A

Omeoprazole

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39
Q

Cells that made digestion,

absorption, and secretion

A

Enterocytes

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40
Q

Secrete lysozymes and defensins that destroy bacteria or produce inflammatory responses.

A

Paneth Cells

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41
Q

The absorptive processes start in: ___________

A

The Jejunum

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42
Q

Is activated to pepsin in the acidic environment of the stomach lumen.

A

Pepsinogen

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43
Q

Is a disaccharide consisting of glucose and fructose

A

Sucrose

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44
Q

Acts on H2 receptors and is activated by gastrin

A

Histamine

45
Q

Digestion and absorption of essentially all major dietary products take place in ______

A

Small Intestine

46
Q

Describe 1st step of digestion

A

Lubrication and homogenization of food with fluids secreted by glands of the intestinal tract.

47
Q

Osmotic retention of water in the lumen leads to:

A

Diarrhea, bloating, and abdominal pain

48
Q

Describe 3rd step of digestion

A

Secretion of hydrogen ion and bicarbonate within different parts of the GI tract to optimize the conditions for enzymic hydrolysis.

49
Q

During periods of health the principal substances absorbed from the colon are:

A

Water and Electrolytes

50
Q

Facilitates absorption of vitamin B 12 in the intestine .

A

Intrinsic factor (IF) secreted by parietal cells

51
Q

In humans, the time needed to replace the entire population of intestinal epithelial cells is:

A

3 to 6 days

52
Q

Where is absorbed medium and short chain FA?

A

Are absorbed into the portal blood

53
Q

Remains inactive in the presence of bile salts normally secreted into the small intestine.

A

Pancreatic Lipase

54
Q

Recycling of bile acids and absorption of the SCFAs produced by:

A

Colonic Bacteria

55
Q

Is the site of activity for a number of digestive enzymes, it is also the barrier that must be traversed by nutrients, water, and electrolytes on the way to the blood or lymph.

A

Brush Border

56
Q

The H + secretion is dependent on: ________

A

The parallel export of K + through luminal K + channels

57
Q

Triggers the release of the main digestive enzymes by the pancreas as well as the contraction of the gallbladder to release bile.

A

Cholecystokinin in pancreatic phase of digestion

58
Q

Responsible for the exit of glucose and galactose from the absorbing cell

A

GLUT-2

59
Q

Cells that secrete mucus

A

Goblet Cells

60
Q

Comprises approximately 30% of the total carbs intake

A

Sucrose

61
Q

Are synthesized as inactive zymogens and are only activated on their release to the gut lumen

A

Enzymes involved in the digestion of protein (proteases)

62
Q

Enzymes in mouth

A

Amilasa and Lingual Lipase

63
Q

Consists of cholesterol, cholesteryl esters, phospholipids, and nonesterified fatty acids (NEFA).

A

Tryacyglycerols

64
Q

Wich Enzyme is responsible for active Pancreatic Lipase?

A

Colipase

-Binds to both the water􏰋lipid interface and the pancreatic lipase, activating the enzyme.

65
Q

Secrete pepsinogen, which is a precursor of pepsin

A

Chief Cells

66
Q

Enzymes secreted by small intestine:

A

Enterokinase, Disaccharides, Maltase, Sucrase, Lactase, Trehalase, Isomaltase, Peptidase, Dipeptidase

67
Q

Luminal digestion of starch ends in small intestine with the action of: ______________

A

Pancreatic a-amilase

68
Q

Cleaves proteins at arginine and lysine residues

A

Trypsin

69
Q

____________ are transferred to the rough endoplasmic reticulum for resynthesis into TGs by a FA binding protein

A

Greater than 12 carbons FA

70
Q

Major enzyme secreted by the pancreas

A

Pancreatic Lipase

71
Q

Enzymes of stomach

A

Pepsin and Gastric Lipase

72
Q

Remove amino acids from the carboxy terminus of the polypeptide

A

Carboxypeptidase

73
Q

Is the most active enzyme, but sucrase and isomaltase also cleave these bonds

A

Glucoamylase

74
Q

Parietal cell activity is stimulated by the action of: ___________

A

Histamine

75
Q

Describe the protein digestion in the stomach.

A
  1. The HCl reduces the pH to 1-􏰋2, with consequent denaturation of dietary proteins
  2. Denaturation unfolds polypeptide chains, making proteins more accessible to proteases
  3. Chief cells of gastric mucosa secrete pepsin
76
Q

Human salivary and pancreatic amylases have optimum activities near ______ pH and are activated by _________.

A

Neutral, Cl

77
Q

Cleaves 100% of sucrose to yield glucose and fructose.

A

Sucrase

78
Q

Is a high-molecular-weight compound consisting of two polysaccharides, amylose and amylopectin

A

Starch

79
Q

Remove amino acids from amino terminus

A

Aminopeptidases

80
Q

Mixing of food and initiation of digestion take place in: ____________

A

The mouth and stomach

81
Q

Transport the lipids to the brush border of the enterocyte

A

Micelles

82
Q

Enzyme secreted by pancreas

A

Amylase, Trypsin, Chymotripsin, Carboxypeptidase, Elastase, etc

83
Q

Secreted bile salts pass into the ileum, where they are reabsorbed and transferred back to the liver through the:________________

A

Enterohepatic Circulation

84
Q

In this patients the SGLT-1 transporter is absent, whereas GLUT-5 is present

A

Patients with intolerance to glucose and galactose

85
Q

Is secreted by G cells and is triggered by food entering the stomach

A

Gastrin

86
Q

Is a rare disease found primarily in children.

A

Intolerance of sucrose and Isomaltose

87
Q

Treatment of acid-related symptoms, such as dyspepsia or gastroesophageal reflux, can be achieved with:

A

Antiacids, H2 antagonist or proton pump inhibitors

88
Q

Act as detergents and reversibly form lipid aggregates, micelles

A

Bile Acids

89
Q

Antiacids function

A

Neutralize PH

90
Q

What happened in the final step of digestion of peptides?

A

The transfer of free amino acids out of the enterocyte into the portal blood

91
Q

Cell proliferation, differentiation, and maturation are influenced by:

A

GI hormones, growth factors, and the nature of the material in the lumen.

92
Q

Is involved in the absorption of water and electrolytes and participates in the recirculation of the bile acids to the liver.

A

Large Intestine

93
Q

Comprises approximately 1% of the total carbs intake

A

Maltose

94
Q

Comprises approximately 50% of the total carbs intake

A

Starch

95
Q

Is a straight-chain polymer of glucose linked by α-1,4-glycosidic bonds

A

Amylose

96
Q

Hydrolysis of oligomers and dimers is mediated by:

A

Membrane-bound enzymes.

97
Q

The end product of digestion of peptides are:

A

Free amino acids and di- and tripeptides.

98
Q

Products of amylase action on starch and other major dietary sugars are hydrolyzed by: _________

A

Brush Border Carbohydrases

99
Q

Generate hydrogen ions through the action of carbonic anhydrase and then pump them into the lumen by an ATP-dependent proton pump on the luminal membrane.

A

Parietal Cells

100
Q

Comprises approximately 6% of the total carbs intake

A

Lactose

101
Q

Is the chemical breakdown of food by enzymes

A

Digestion

102
Q

Emulsification of dietary lipids are mediated by:

A

Bile Acids

103
Q

Converts trypsinogen to active trypsin

A

Duodenal Enteropeptidase

104
Q

Uptake processes include:

A

Active and Passive Diffusion

105
Q

Fructose is absorbed by:_____________

A

Na+ independent facilitated diffusion

106
Q

Are absorbed by secondary active transport via an Na +- dependent carrier system (SGLT-1).

A

Glucose and Galactose

107
Q

Control the flux of solutes and fluid between the lumen and blood

A

Enterocyte Membrane

108
Q

Pass directly through the enterocytes into the hepatic portal system

A

Medium and Short Chain FA (>10)

GI Tract Biochem (7 decks)

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