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CNS Exam > Section 1A > Flashcards

Section 1A Flashcards

1
Q

Alimentary Tract consists of:

A

mouth, tongue, teeth and throat

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2
Q

Alimentary tract contributes to …

A

MECHANICAL digestion of food - preparing a food bolus by biting, chewing, and swallowing

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3
Q

salivary enzymes released when chewing:

A

large amounts of CHO-hydrolyzing amylase
very small amounts of lipid-hydrolyzing lipase

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4
Q

Amylase is to __________ as Lipase is to ________

A

Amylase - CHO
Lipase - Lipids

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5
Q

Esophagus

A

tube from mouth to stomach lined with mucus and smooth muscle
NO digestion
pushes food down to stomach via peristaltic wave-like contractions

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6
Q

Regurgitation of food back to throat is prevented by…

A

upper and lower esophageal sphincters
PRIMARILY by the LES !

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7
Q

Lower Esophageal Sphincter (LES)

A

between esophagus and stomach preventing stomach acids to come back up

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8
Q

Chemical and Enzymatic Hydrolysis of food in the _____________

A

stomach

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9
Q

Chemical and enzymatic hydrolysis of food includes:

A

holding, preparing, and mixing food material
regulating osmolarity of ingested food
reducing bacterial load through acid secretion

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10
Q

_________ of the stomach secrete lipase

A

chief cells

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11
Q

Chief cells —-

A

stomach
secrete lipase
break down dietary triglycerides (triacylglycerols) into FFAs and diglycerides (diacylglycerols), and pepsinogen (precursor of pepsin)

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12
Q

Pepsinogen is the precursor of….

A

pepsin

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13
Q

pepsin initiates ….

A

the hydrolysis of food proteins

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14
Q

_______ of the stomach secrete intrinsic factor

A

parietal cells

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15
Q

Intrinsic factor

A

small protein required for absorption of B12 and HCl

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16
Q

_________ of the stomach secrete mucus containing glycoproteins and bicarbonate

A

mucous cells

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17
Q

Secretions from Mucous cells

A

mucus containing glycoproteins and bicarbonate that PROTECT the gastric mucosa from acid damage and autodigestion

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18
Q

Gastric Acid requires what kind of environment

A

performs a # of preliminary digestive roles that require an acidic environment

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19
Q

Gastric acid roles

A
  1. destruction of microorganisms
  2. activation of pepsinogen to pepsin
  3. activation of intrinsic factor
  4. denaturation (loss of three-dimensional conformation) of macromolecules
  5. facilitation of the breakdown of protein and polypepides by pepsin
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20
Q

presence of food protein in the stomach triggers ______

A

gastric secretion

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21
Q

Gastrin secreted by _____

A

gastric endocrine cells

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22
Q

Gastrin acts on

A
  1. gastric parietal and chief cells to stimulate intragastric secretion of HCl and Pepsinogen
  2. stimulates gastric peristalsis and maintains the proliferation of gastric parietal cells
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23
Q

__________ intragastric acidity inhibits (hinders) continued gastrin secretion

A

increasing

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24
Q

Peristaltic contractions of the _____________________ propel digesta toward the gastric pylorus

A

distal stomach

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25
Q

while food is propelled towards the gastric pylorus, the gastric pylorus contracts in opposition to gastric peristalsis, but_______ which causes _____

A

it does not close – causes sufficiently small particles, liquids, and liquified digesta to pass through into the proximal small intestine

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26
Q

After the stomach — digesta goes into the _______

A

small intestine

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27
Q

If foods particles are too big to make it through the residual pyloric opening into the small intestine, they _____________

A

are retropelled back into the stomach for further preliminary digestion

ingested fats can also turn into fine lipid droplets (<5 mm diameter)

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28
Q

what is the major anatomical site of food digestion and nutrient absorption

A

small intestine

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29
Q

Brush Border — what is it, what is it composed of

A

luminal surface of the SI
composed of microvilli that dramatically increase available absorptive surface area of the small intestine

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30
Q

Microvilli

A

extravaginations of the plasma membranes of the absorptive cells of the intestinal mucosa

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31
Q

Absorptive enterocytes originate from __________________________ in the ______________

A

originate from stem cells in the intervillar crypts

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32
Q

Where do enterocytes differentiate?

A

at the luminal surface of the mucosa

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33
Q

How long do enterocytes survive

A

about 72 hours — then they undergo apoptosis and lose their attachment to the mucosal basement membrane (desquamation)

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34
Q

Most proximal upper section of the small intestine?

A

the short duodenum

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35
Q

Chemical degradation of partially digested food into individual nutrients begins in ….

A

the short duodenum

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36
Q

seconds section of the SI

A

jejunum

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37
Q

Third and distal part of the SI

A

ileum

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38
Q

Major sites of nutrient absorption

A

jejunum and ileum

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39
Q

_______ transfers any undigested food materials into the large intestine

A

distal ileum

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40
Q

________ entering ________ stimulates the enteric secretion of secretin into systemic circulation

A

Acidic chyme entering the proximal duodenum stimulates secretion of secretin into systemic circulation

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41
Q

Secretion stimulates……

A

pancreatic secretion of bicarbonate into the ductal system

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42
Q

the ductal system

A

terminates in the common bile duct

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43
Q

Fat or Protein entering the proximal duodenum stimulate ________ of _____ into systemic circulation

A

Fat or Protein entering the proximal duodenum stimulate duodenal secretion of cholecystokinin (CCK) into systemic circulation

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44
Q

cholecystokinin (CCK)

A

stimulates pancreatic secretion of zymogens into the ductal system
stimulates gall bladder contraction, propelling bile into the common bile duct

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45
Q

Zymogens

A

inactive digestive enzyme precursors

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46
Q

Common bile duct empties into the ____ (and what does it do there)

A

proximal duodenum, transferring pancreatic zymogens and hepatic bile constituents into the duodenal lumen

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47
Q

In the duodenal lumen, the pancreatic zymogens and hepatic bile constituents mix with the digesta to ___________ the conversation of food components into __________

A

In the duodenal lumen, the pancreatic zymogens and hepatic bile constituents mix with the digesta to ACCELERATE the conversation of food components into ABSORBABLE INDIVIDUAL NUTRIENTS AND SMALL MOLECULES

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48
Q

___________ duodenal distension triggers secretion of gastric inhibitory peptide which ________ gastric motility and _________ the rate of further gastric emptying

A

INCREASING duodenal distension triggers secretion of gastric inhibitory peptide which INHIBITS gastric motility and SLOWS the rate of further gastric emptying

So increasing the pressure in the duodenum (inflammation) triggers secretion of gastric inhibitory peptide. This hinders gastric motility and slows down gastric emptying – think inflammation in your SI

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49
Q

Pancreatic zymogens that play a major role in food digestion are —- (6)

A

Trypsinogen
Proelastase
Chymotrypsinogen
Procolipase
Procarboxypeptidase A
Procarboxypeptidase B

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50
Q

When pancreatic zymogens reach the SI ______ secreted by duodenal enterocytes converts _______ to _______

A

When pancreatic zymogens reach the SI, ENTEROKINASE secreted by duodenal enterocytes converts TRYPSINOGEN to TRYPSIN

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51
Q

Enterokinase Enzyme

A

secreted by the duodenal enterocytes
triggered by pancreatic zymogens reaching the SI
REQUIRED for trypsin activation

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52
Q

Trypsin

A

converts the OTHER zymogens to:
- Proelastase TO elastase
- Chymotrypsinogen TO chymotrypsin
- Procolipase TO colipase
- Procarboxypeptidase A TO carboxypeptidase A
- Procarboxypeptidase B TO carboxypeptidase B

Trypsin NEEDED to convert the others so in turn enterokinase is required to activate all of the pancreatic zymogens

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53
Q

Serine Proteases

A

trypsin, chymotrypsin, and elastase (same as the endopeptidases)

means that a serine is required at the enzymes’ active site

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54
Q

Endopeptidases

A

trypsin, chymotrypsin, and elastase (same as the serine proteases)

hydrolyze peptide bonds within polypeptides

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55
Q

carboxypeptidases are

A

zinc-requiring metalloenzyme exopeptidases —- they cleave single carboxyterminal amino acids from polypeptides

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56
Q

Amylase

A

secreted by the pancreas
performs initial digestion of starches to produce glucosyl oligosaccharides and disaccharides

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57
Q

Lipase

A

secreted by the pancreas
hydrolyzes dietary fats that have been emulsified by bile salts into fatty acids and glycerol

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58
Q

Cholesteryl Esterase

A

secreted by the pancreas
cleaves cholesteryl esters

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59
Q

Secreted by the Pancreas

A

amylase, lipase, cholesteryl esterase, ribonuclease deoxyridonuclease, zymogens

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60
Q

Brush Border Enzymes

A

Ectozymes

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61
Q

Ectozymes

A

brush border enzymes
associated with and attached to microvillar surfaces of the SI
Produced by enterocytes

complete the final steps in hydrolysis of amylase-digested CHOs to monosaccharides and of protease-digested PROTEINS to absorbable free AAs, dipeptides, and tripeptides

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62
Q

Oligosaccharidases, disaccharidases, and pepidases

A

ectozymes

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63
Q

What completes the final steps in hydrolysis of amylase-digested CHOs to monosaccharides and of protease-digested PROTEINS to absorbable free AAs, dipeptides, and tripeptides

A

Ectozymes

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64
Q

What buffers gastric HCl into a weaker acid, H2CO3, maintaining duodenal pH near the neutrality optimum for digestive enzyme function

A

pancreatic bicarbonate

in other words - this helps to keep the pH of the duodenum near optimum for digestive enzyme function

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65
Q

Efficiency of digestive enzymes is affected primarily by

A

local pH

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66
Q

_______ availability affects the ionization of the active state of an enzyme

A

proton

if an enzyme and substrate have the greatest affinity when the enzyme is in a protonated form, an alkaline pH will cause the enzyme to become depronated, substrate affinity will decrease and the rate of the rxn will decline

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67
Q

Extremes of pH can lead to _____ of enzymes

A

denaturation

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68
Q

Salivary amylase works best at what pH

A

6.75 - 7.00

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69
Q

gastric pepsin and lipase function optimally at what pH

A

1.5 - 3.5

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70
Q

enzyme that is activated by protons_____

A

gastric pepsin – because a strong acid like gastric HCl will liberate all H+ in water component of the digesta

this then dramatically decreases the pH

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71
Q

Enzymes that are deactivated by presence of free protons include : (3)

A

gastric lipase
salivary amylase
lingual lipase

these function most efficiently at neutral or higher alkaline pH

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72
Q

Bile

A

a watery greenish fluid stored in the gallbladder

contains cholic acid, chenodeoxycholic acid, taurine, glycine, cholesterol, electrolytes, and water (6-7 L/day on average in adults)

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73
Q

Primary role of liver in food digestion and nutrient absorption is excretion of

A

bile

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74
Q

organic and mineral components of bile form

A

bile salts

usually electrolyte salts of cholic and chenodeoxycholic acids

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75
Q

bile salts

A

emulsify the fine lipid droplets reaching the intestine from the stomach which increases the droplet surface area exposed to the combined actions of pancreatic lipase and colipase and is required for these enzymes to be effective

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76
Q

________ and ______ hydrolyze triglycerides to release monoglycerides (monoacylglycerols) and free fatty acids

A

pancreatic lipase and colipase hydrolyze triglycerides to release monoglycerides (monoacylglycerols) and free fatty acids

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77
Q

What things cannot penetrate the unstirred water layer that separates the epithelial surface of the SI from the intestinal lumen (and how they can be absorbed) (5)

A

monoglycerides
FFAs
cholesterol
phospholipid digestion products
other fat-soluble food components

their absorption depends on ability to aggregate spontaneously with bile salts and become incorporated with micelles

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78
Q

Micelles

A

vaguely spherical clusters of bile salts

collections of lipid soluble dietary subcomponents surrounded by a layer of water soluble bile salts

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79
Q

why are micelles helpful in absorption of the things that cannot penetrate the water layer?

A

solubility characteristics of the bile salt layer allows ready penetration of the unstirred water layer by micelles; the complex breaks down upon reaching the brush border, allowing rapid diffusion of their lipid components down concentration gradients into enterocytes

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80
Q

Where are lipids and lipid compounds repackaged into large protein-coated chylomicrons that are secreted into the lacteals?

A

endoplasmic reticulum of the enterocytes

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81
Q

protein-coated on the chylomicrons means …..

A

it is water soluble

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82
Q

Chylomicrons get secreted into the lacteals then ….

A

flow through the lymphatic system and enter the circulation via the thoracic duct

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83
Q

most of the water and bile salts excreted into the intestine are reabsorbed in the ______

A

ILEUM

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84
Q

Bile salts are transported back to the liver via

A

enterohepatic circulation

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85
Q

portion of cholesterol in bile is not incorporated into micelles and is excreted in the ______

A

feces

as is 1% to 2% of the water that was delivered to the proximal small intestine)

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86
Q

what utilizes the potential energy associated with the diffusion of water through a SEMIPERMEABLE membrane from an area of HIGH osmotic pressure to LOWER osmotic pressure

A

Osmosis

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87
Q

Osmotic movement of nutrients is limited to the _______ pathway

A

paracellular pathway

where water and electrolytes cross tight junctions between adjacent enterocytes

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88
Q

what uses HYDROSTATIC PRESSURE to drive the movement of solutes and water through a SEMIPERMEABLE membrane from a region of HIGHER hydrostatic pressure to a region of LOWER hydrostatic pressure

A

Filtration

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89
Q

What utilizes the potential energy created by a difference in nutrient concentration across a membrane to move nutrients from an area of HIGHER concentration to an area of LOWER concentration?

A

Passive diffusion (simple diffusion)

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90
Q

_________ compounds enter intestinal cells by passive diffusion from brush border into the cell cytosol

A

lipid soluble compounds

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91
Q

What utilizes a lipid soluble membrane carrier protein to pass through membranes moving down its concentration gradient?

A

facilitated diffusion (carrier-mediated transport)

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92
Q

_______ are transported across biological membranes via facilitated diffusion

A

Most Carbohydrates utilize facilitated diffusion

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93
Q

In what does a nutrient move through MUCOSAL cell membranes AGAINST a concentration gradient requiring the participation of a membrane carrier protein (receptor) and consumes biochemical energy provided by ATP

A

active transport (solute transport)

Active - needs ATP

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94
Q

_______ and ______ are absorbed via active transport

A

amino acids and ions

Active transport, uses Atp, Amino Acids and ions, Against the concentration gradient

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95
Q

What prevents components of ingesta and their degradation products from penetrating into the GI circulation (and most importantly the portal vein)

A

Intestinal Barrier

96
Q

An intact intestinal barrier maintains –

A

relative impermeability of the GI tract to exogenous materials and organisms
prevents absorption and translocation of intact microorganisms, microbial endotoxins, and food allergens

97
Q

Factors that preserve intestinal barrier function: (6)

A

antibacterial and antiviral secretions of nonpathologic microflora
endogenous mucous secretions
intercellular “tight junctions”
intestinal epithelial secretion of lectins and anti-adhesion glycoproteins
peristaltic movement of digesta
enterocytic filtration (lysosomal hydrolysis of pathogens and toxins within enterocytes)

98
Q

Antimicrobial defenses within the intestinal tract rely heavily on the secretion of ________ by _____________

A

secretory IgA (sIgA) by gut-associated lymphoid tissue (GALT)

99
Q

GALT contains about __________ of the total number of immune cells in the body, scattered throughout the intestinal tract

A

50-60%

100
Q

What is the first line of defense against environmental assault?

A

GALT (gut-associated lymphoid tissue)

101
Q

What is the first line of defense against environmental assault?

A

GALT (gut-associated lymphoid tissue)

provides both cell-mediated immunity and humoral immunity via secretory IgA

102
Q

When intestinal permeability increases secondary to compromise of intestinal barrier function, what happens?

A

failure of exclusion
increased intestinal permeability
antigen-induced disease

103
Q

_______________ diseases may occur when food components or bacterial antigens share a common antigenic determinant (epitope) with both a virus or other pathogenic microorganisms to which the host has been exposed previously and a host cell membrane components

A

Autoimmune-like diseases

104
Q

Small molecules (like monosaccharides) are absorbed by _______ via _____________

A

enterocytes via direct transcellular uptake

105
Q

measuring the rate of __________ of a test dose of a nonmetabolizable small molecules (monosaccharide, mannitol) provide information on _________

A

urinary excretion

the rate of transcellular uptake by enterocytes and, indirectly, the overall health status of small intestinal villi

106
Q

Large molecules do not undergo transcellular uptake and normally are prevented from _______

A

passing between enterocytes (paracellular uptake) by intercellular “tight junctions”

107
Q

Urinary excretion of:
Mannitol NORMAL or HIGH
Lactulose HIGH

Dx?

A

increased small intestinal permeability

108
Q

Urinary excretion of:
Mannitol LOW
Lactulose LOW

Dx?

A

small intestinal malabsorption

109
Q

Urinary excretion of:
Mannitol LOW
Lactulose HIGH

Dx?

A

increased small intestinal permeability and small intestinal malabsorption

110
Q

use of lactulose to detect increased intestinal permeability may be associated with ____

A

high incidence of false positive results

111
Q

Intestinal impermeability may be restored by any means that will either :

A

reduced the amount of proteinaceous residue reaching the ileum,
increase epithelial integrity
support the GALT

Examples: increasing the effectiveness of digestive enzymes by oral supplementation with purified or semi-purified enzyme preparations and maintaining adequate intraepithelial glutamine concentrations

112
Q

Glutathione

A

intestinal antioxidant
short peptide

major intestinal extracellular antioxidant

113
Q

highest tissue content of GSH (glutathione) is in:

A

human gastric and duodenal epithelia

114
Q

Where does GSH activity reside

A

on the outer (luminal) enterocyte cell membrane and rapidly neutralizes oxidizing ingesta and breakdown of products of digestion

115
Q

Within enterocytes – GSH synthesis produces an alternative pathway for________

A

utilization of homocysteine that is independent of B-vitamin status (but only with adequate intracellular glutamine concentration)

116
Q

What is utilized to make glutathione

A

Homocysteine —> cystathione
cystathione —–> cysteine

Glutamine —-> glutamate

Cysteine + glutamate —-> y-glutamylcysteine

y-glutamylcysteine + glycine –> glutathione

117
Q

intact glutathione administered via parenteral nutrition contributes to whole-body glutathione — oral glutathione ——–

A

undergoes proteolytic digestion before it can be absorbed

118
Q

intact glutathione may neutralize toxins within?

A

the intestinal lumen

119
Q

Primary fuel source for enterocytes?

A

glutamine

120
Q

Glutamine

A

Amino Acid

required primary fuel source for enterocytes

provides substrates for the enteric tricarboxylic acid cycle
high intraenterocyte glutamine concentration is required to supply substrates for the production of polyamines and DNA in support of normal rates of cell desquamation and replication

121
Q

During illness, trauma, and stress _____________________ is diverted to the immune system, depleting enterocytes of _________ and __________

A

During illness, trauma, and stress, GLUTAMINE is diverted to the immune system, depleting enterocytes of GLUTAMINE and GLUTATHIONE

122
Q

Glutamine inadequacy is associated with

A

acceleration of apoptosis in the SI
causing accelerated cell death and desquamation without compensatory acceleration of stem cell proliferation

imbalance in tissue turnover produces thinning of villi with deccreased digestive function, decreased absorptive function, loss of intestinal barrier integrity, and increased translocation of antigens and pathogens from the intestinal lumen into the extravellular fluid and blood

123
Q

Maintenance of intra-intestinal glutamine supply prevents—-

A

disruption in intestinal function

Examples: very low birth weight infants have immature intestinal anatomy, incomplete barrier function, and increased incidence of septic infections —- oral supplementation with L-glutamine decreases incidence of septic infections in very-lower-birth weight infants

124
Q

Large intestine is composed of: (4)

A

ascending colon
transverse colon
descending colon
sigmoid colon

125
Q

Major functions of the large intestine (4)

A

reabsorb water from the digesta
absorb vitamins produced in intestinal bacteria
provide an environment conducive to the fermentation of dietary fiber by resident microbes
eliminate dried residues (undigested and unabsorbed material) as feces

126
Q

products of dietary fiber fermentation that AVOID microbial ingestion are: (3)

A

primary energy sources for colonocytes
support colonocyte metabolism
maintain colonocyte apoptotic synchrony

127
Q

_________________ of ingested dietary fiber exhibit the “classical” function of stool softening and binging for fecal excretion of bile salts, cholesterol, and steroid hormones and their metabolic derivatives

A

Unfermented Fractions

128
Q

Categories of dietary fiber:

A

soluble
insoluble
nonfermentable

129
Q

What type of fiber:
beta-glucans (arabinogalactans, lactoferrin), gums, mucilages, and pectins

A

Soluble

130
Q

Which dietary fiber comprises 10-20% of the total dietary fiber content of fruit, okra, beans, turnips, oats, parsnips, sea weeds, and prunes

A

soluble

131
Q

Which dietary fiber include the celluloses and the lignins

A

insoluble

132
Q

what is classified as both soluble and insoluble

A

hemicellulose

133
Q

Most adults with healthy colons should ingest _____ to ______ g of soluble fiber daily

A

25-35 g

134
Q

foods rich in soluble fiber often contain ____________ that prevent the digestion of dietary fat and may induce deficiencies in essential fatty acids and fat - soluble vitamins

A

lipase inhibitors

135
Q

Soluble fiber intake greater than ______ g/day may inhibit the digestion of non-fiber CHO, increasing the amount of sugar and starch reaching the colon

A

50 g/day

136
Q

What type of dietary fiber includes oat hulls, methylcellulose, and wood pulp cellulose

A

nonfermentable

137
Q

Which dietary fiber functions in the colon to increase the bacterial mass of the stool (by adhesion), decrease the absorption of glucose, and increase the glucose content of stool (by interfering with CHO digestion in the small intestine), dilute pathogens and toxins in digesta and stool, increase rate of passage stimulating peristaltic concentrations, inhibit the inflammatory responses to bacterial infections by blocking microbial access to the intestinal mucosa, and inhibit phagocytotic capacity of intestinal macrophages (possibly by interfering with macrophage-secreted oxidizing compounds

A

nonfermentable

138
Q

What happens at the colon?

A

human colonocytes and immune cells, microbes and ingested foods interact in the near-absence of oxygen

139
Q

GI tract contains ____ living bacteria, representing over ____ individual species

A

GI tract contains 10^14 living bacteria, representing over 400 individual species

140
Q

goal of dietary maintenance of colon health

A

foster stable steady-state, with the human host and its microbial symbiotes and pathogens in harmonic balance

141
Q

the most common microorganisms in the stomach and duodenum are: (3)

A

Lactobacilli
streptococci
yeasts

142
Q

Small pH differences along the small intestine favor:

A

Lactobacilli
Enterobacteriaceae
streptococci
bacteroides
bifidobacteria
fusobacteria

in the human jejenum and ileum

143
Q

the most common microorganisms in the colon are: (11)

A

bifidobacteria,
lactobacilli,
Streptococci
Bacteroides
Fusibacteria
Enterobacteriaceae
Pseudomonas
Clostridia
Proteus species
yeasts
protozoa

Colon harbors larger diversity of organisms

144
Q

The most beneficial individual species for the GI tract:

A

Bifidobacterium bifidus (bifidum),
Bifidobacterium infantis
Lactobaacillus acidophilus,
Lactobacillus bulgaricus
Lacto brevis
Lacto casei
lacto cellobiosus
lacto fermenti
lacto leichmannii
lacto plantarum
lacto rhamnosus,
lact saliverius
lacto sporogenes
Saccharomyces boulardii
Enterococcis faecium
Streptococcus Thermophilus

145
Q

Most common microorganism in healthy human digestive tract

predominant microbes in human breast milk

A

Bifidobacteria

146
Q

what comprises about 50% of all intestinal microflora and ferments dietary fiber CHOs to short chain fatty acids

A

Bifidobacteria

147
Q

Bifidobacteria function (8)

A

enhance epithelial barrier fxn by reducing pathogenic load
reduce risk for developing colon cancer by metabolizing carcinogens and pro-carcinogens
suppress growth of pathogenic species by maintaining a slightly acidic colonic pH
binding to adhesion proteins on pathogens (competitive exclusion)
secretion of adhesion-inhibiting proteins
secretion of broad-spectrum antibiotics (like bulgarican)
secretion of antiviral L-bifidus factor (also found in cow’s milk)
and stimulation of GALT phagocytosis of pathogens

148
Q

What comprises about 25% of all intestinal microflora

A

Lactobacilli

149
Q

Types of Lactobacilli that are most common (5)

A

L. brevis
L. acidophilus
L. bulgaricus
L. casei
L. rhamnosus

150
Q

Lactobacilli roles (

A

ferments dietary fiber CHOs to lactic acid and short chain fatty acids – contributes to the slightly acidic colonic pH
enhance epithelial barrier integrity by reducing pathogenic load
reduce risk of colon cancer by binding heterocyclic mutagens, deconjugating bile acids and binding and metabolizing cholesterol

Also ameliorate symptoms of lactose intolerance in individuals with inadequate lactase production by secretion of beta-galactosidase (lactose –> glucose + galactose)

suppresses growth of pathogenic species by a variety of mechanisms, including maintaining a slightly acidic colonic pH, binding to adhesion proteins on pathogens (“competitive exclusion”), secretion of adhesion-inhibiting proteins, competing for adhesion sites on enterocytes, secretion of species-specific antibiotics (acidolin, acidophilin, lactobacilin, and lactocidin)
secretion of hydrogen peroxide
stimulation of DALT production and secretion of secretory IgA (sIgA)
inhibition of bacterial enzymes (glucuronidase, beta-glucuronidase, and nitroreductase)
stimulation of colonic peristalsis (reducing time for colonocyte-pathogen interactions)

151
Q

Saccharomyces boulardii also known as_____

A

yeast !

152
Q

found both in small and large intestine

A

Saccharomyces boulardii (yeast)

153
Q

Saccharomyces boulardii (yeast)

A

antagonistic to Candida albicans

inhibit effects of cholera toxin
inhibit adhesion of amoeba to intestinal brush border
stimulate enterocyte secretion of brush border enzymes (sucrase, lactase, maltase)
stimulate GALT production and secretion of sIgA

154
Q

Oral supplements with what have been found to reduce severity and duration of childhood rotaviral diarrhea

A

Saccharomyces boulardii (yeast)

155
Q

Colon obtains 70% of its nutrients directly from _________

A

the digesta

156
Q

Microbial fermentation of fermentable dietary fibers results in the production of ?

A

SCFAs – acetate, propionate, butyrate

the relative proportions of the SCFA’s produced reflect substrate supply and the relative proportions of the microbial species present

157
Q

What is especially important to human colonocytes?

A

butyrate

158
Q

what is metabolized to Acetyle CoA within Colonocytes?

A

butyrate

159
Q

what is the primary energy source for colonocytes and is required for the formation and maintenance of intercellular tight junctions

A

Acetyl CoA

160
Q

Within the colon, butyrate stimulates: (7)

A

secretion of enteroglucagon (hormone that is trophic for intestinal villi)
stimulate T-lymphocyte proliferation in GALT
attenuates B-lymphocyte reactivity in GALT
inhibits TNF-alpha-induced activation of the nuclear transcription factor (procarcinogenic) NF-kB in colonocytes
inhibits TNF-alpha-induced secretion of pro-inflammatory IL-8 by colonocytes
inhibits growth of pro-inflammatory Clostridium species
required for maintenance of colonocyte apoptotic destiny

161
Q

Hormone that is trophic (stimulating for activity) for intestinal villi?

A

enteroglucagon

162
Q

Butyrate insufficiency within the colon results in - (5)

A

depletion of intracolonocyte acetyl-CoA
increased introcolonocyte cyclic AMP concentration
inhibition of apoptosis
failure of intercellular “tight junctions”
impairment of epithelial barrier integrity in the colon and increased large intestinal epithelial permeability

163
Q

Consequence of butyrate insufficiency secondary to inadequate fermentation of butyrate precursor dietary fiber include: (3)

A

intraepithelial inflammation
systemic illness
inflammatory syndromes that mimic autoimmune dx

164
Q

balance within the colon

A

ecologic harmony

165
Q

dietary and medical practices that disturb the balance within the colon (ecologic harmony) include:

A

infant formula feeding
low fiber diets
diets high in resistance starch content (starches resistance to digestion by amylase)
inadequate intake of glutamine

166
Q

Starches that are resistant to digestion by amylase

A

resistance starches

167
Q

things that desensitize the colon

A

inadequate production of pancreatic zymogens that results in poor digestion of dietary sugars
oral antibiotic therapy
ingestion of zenobiotics and exotoxins

168
Q

The human GI tact is ________ at birth

A

sterile

169
Q

Parturition

A

action of giving birth

the tract is seeded initially by maternal vaginal organisms to child

170
Q

When does mammary gland microflora contribute to early Bifidobacteria for a newborn?

A

breastfeeding

171
Q

When else contributes to early intestinal ecology (besides breastfeeding and childbirth)

A

foodborne microflora and self-inoculation via coprophagy (eating of feces or dung)

172
Q

maternal antibodies get transferred in

A

colostrum

173
Q

In breastfed infants, over ____ of intestinal bacteria consist of ____________

A

In breastfed infants, over 90% of intestinal bacteria consist of Bifidobacterium infantis

174
Q

In non-breast fed infants there are ______ #s of Bifidobacteria and Lactobacilli and ________ numbers of Enterococci, Coliforms, and Clostridia

A

In non-breast fed infants there are LOW #s of Bifidobacteria and Lactobacilli and HIGH numbers of Enterococci, Coliforms, and Clostridia

175
Q

Clinically, feeding with infant formula instead of breast mild is associated with : (3)

A

Sepsis, necrotizing enterocolitis, and gastroenteritis

176
Q

what causes a lack of substrate for fermentation that prevents the beneficial mild acidification of the colonic lumen and results in its relative alkalinization

A

low fiber diet

177
Q

the rise in colon intraluminal pH is accompanied by :

A

decreased supply of butyrate to colonocytes with disruption of colonocyte apoptotic synchrony and persistence of senescent colonocytes with increased probability of undergoing precarcinogenic and carcinogenic change

178
Q

what decreases the rate of passage, increases the time available for absorption of water by colonocytes, and provides increased exposure of colonocytes to toxins, mutagens and carcinogens

A

lack of sufficient amounts of dietary fiber in the colon

179
Q

decreased water absorption to stool results in increased stool hardness and incidence of ______

A

constipation

180
Q

what will increase the amount of fermentable nonfiber CHO reaching the colon

A

incomplete digestion of dietary sugars

181
Q

fermentation of sugars within the colon result in

A

hyper-acidification of intraluminal pH and an increase in microbial production of SH2

182
Q

SH2 readily enters colonocytes where it acts as an::

A

inhibitor of enzymatic conversion of butyrate to acetyl CoA

183
Q

what produces leaky tight junctions with an increase in intestinal permeability, increased risk for energy deficit in colonocytes

A

Intracolonocyte acetyl CoA deficiency

184
Q

decreased colonocyte oxidation of butyrate produces

A

delayed colonocyte apoptosis with increased colonocyte exposure to toxins, mutagens, procarcinogens, and carcinogens and increased risk for colorectal carcinoma

185
Q

what kills Lactobacilli and Bifidobacteria although usually targeted at pathogenic organisms

A

oral antibiotics

186
Q

as the numbers of Lacobacilli and Bifidobacteria decrease due to oral antibiotic, what increases?

A

the pathogenic bacterial species

when this happens it has a severe impact on Colon health and causes colonocytes to have increased exposure to pathogens

187
Q

most pathogenic species are insufficient fermenters of

A

dietary fibers

188
Q

When taking antibiotics, intestinal permeability increases leading to

A

increased exposure of intestinal mucosa to pathogen-produced irritants decreases the synchrony of colonic smooth muscle contractions and commonly induces diarrhea

189
Q

environmental toxins can damage the:

A

colonic mucosa both directly and following their conversion to reactive metabolites in the liver and excretion into the intestinal tract via the bile

190
Q

the proportion of reactive metabolites in the colon reflect the interplay of the genetic diversity of hepatic mixed function oxidases and:

A

the extent of exposure to environmental toxins

191
Q

environmental toxins and their metabolites also interact with?

A

pathogens

for example: bacteria may deconjugate reactive metabolites reaching the colon via the bile, liberating highly reactive (and usually highly oxidizing or DNA damanging) compounts

192
Q

environmental toxins and their metabolites also interact with?

A

pathogens

for example: bacteria may deconjugate reactive metabolites reaching the colon via the bile, liberating highly reactive (and usually highly oxidizing or DNA damaging) compounds

193
Q

non-digestible fermentable CHOs that encourage beneficial change in the host’s microbial balance

A

prebiotics

194
Q

non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and activity of one or more bacterial species in the colon, thereby improving the host health

A

prebiotics

195
Q

most widely available prebiotic:

A

CHOs (usually oligomers) that are not hydrolyzed or absorbed in the stomach or intestines and that are selectively fermented by non-pathogenic microbes

196
Q

the fermentation of prebiotic CHOs produces ________ that are beneficial to the human colon

A

metabolic byproducts

197
Q

Common sources of prebiotic fructans (fructooligosaccharides; FOS) and inuilin

A

wheat, onions, asparagus, chicory, banana, and artichoke

198
Q

Oligofructoses from other plant sources include:

A

galactooligosaccharides and levans

These compounds get converted to SCFAs by intestinal microbes and provide about 70%of the metabolizable energy of an equal weight of sucrose

199
Q

GRAS

A

generally recognized as safe

200
Q

__ to ___ % of the population is sensitive to oligofructoses

A

1-4%

201
Q

Fructooligosaccharides (FOS)

A

specifically fermented SCFA’s by Bifidobacteria and are not converted to lactic acid and do not induce lactic acidosis

202
Q

Supplimenting with 4g/day of FOS

A

increases the proportion of bifidobacteria in the colon

203
Q

Oligofructose roles:

A

increases calcium absorption in men and women
reduce the number of aberrant crypt foci in the colon
reduces the incidence of inducible mammary tumors in animal models of cancer

204
Q

products of oligofructose fermentation inhibit:

A

hepatic triglyceride synthesis

205
Q

oral deitary supplements containing live microbes that beneficially affect the hosts microbial balance

A

probiotics

206
Q

when effective, probiotics can”

A

increase the numbers of intestinal Bifidobacteria and Lactobacilli
decrease microbial species that do not ferment fiber to SCFAs

207
Q

Probiotic supplement should survive passage through:

A

the stomach and small intestine to reach the large intestine
produce SCFAs from dietary fiber
maintain colonic pH at about 6
prevent the adherence of pathogens to the colonic mucosa
adhere to human colonocytes in situ
be capable of eventually permanently repopulating the colon

208
Q

Reseeding with adherent probiotic species required at least ____ (time and how)

A

6 months of daily ingestion of at least 10 billion colony forming units (10^10 CFU) per species

209
Q

Is reseeding possible for all people?

A

no, some will require life-long daily supplementation

210
Q

supplementation with a pre/probiotic combo consistently has either:

A

prevented or produced significant reductions in the severity and duration of colonic diarrheas, including infant formula induced diarrheas, childhood viral diarrhea, traveler’s nonbacterial diarrhea, antibiotic-induced diarrhea, diarrhea accompanying AIDS enteropathy and diarrhea caused by Clostridium difficile infection (C.diff)

Has helped with reducing need for parenteral feeding in pts with small bowel bacterial overgrowth (dysbacteriosis) and inflammatory bowel disease

211
Q

what is the leading cause of nosocomially acquired infection

A

C. diff

212
Q

C.diff is found in ____ % of all inpatients, and infection with it causes more than_____% of all interic infections

A

20, 70

213
Q

supplementation with oral combination of pre/probiotic is _________ in the prevention or treatment of most other bacterial (small intestinal) diarrheas

A

ineffective

214
Q

system that plays important role in regulation of digestive system function:

A

nervous system

215
Q

Extrinsic nerves to the digestive system from the unconscious part of the brain or spinal cord respond to the presence of food in the alimentary tract by

A

stimulating the local release of acetylcholine, which causes intestinal smooth muscle contraction, squeezing and pushing food and fluids along the digestive tract and stimulating the release of digestive enzymes

216
Q

in response to the emptying of the digestion tract,

A

adrenaline (epinephrine) is secreted centrally, which relaxes the muscles of the stomach and intestine and decreases the flow of blood to the organs

217
Q

intrinsic nerves in the walls of the esophagus, stomach, small intestine, and colon are excited when

A

the walls of the hollow organs are stretched by food; in response, the movement of food may be increased or decreased

218
Q

premature infants have decreased ability to secrete

A

gastric pepsin, lipase, pancreatic trypsinogen, lipase, amylase, and chymotrypsinogen

they are unable to form micelles with dietary fat

enterocyte secretion of the ectoenzymes, enterokinases, and lactase, also are reduced

219
Q

normal term infants exhibit _____ and _____ activities similar to those in adults, while ____, ____, and _____ secretion is impaired compared to that of an adult.

A

pepsin and lipase

pancreatic enzyme, bile, and enterokinase

therefore the ability to digest dietary starches and animal fats is minimal until about 6 months of ago

220
Q

Enterokinase activity reaches adult levels at about ___ years of age

A

4

221
Q

examples of dietary nutrients that are NOT absorbed directly into the enterohepatic portal blood system include:

A

long-chain fatty acids

222
Q

examples of dietary nutrients that ARE absorbed directly into the enterohepatic portal blood system include:

A

amino acids
medium-chain fatty acids
monosaccharides

223
Q

hormone responsible for the decrease in GI smooth muscle tone and motility during pregnancy is

A

progesterone

224
Q

ingestion of a meal containing large amounts of saturated fat will result in a transient increase in the serum concentration of

A

chylomicrons

225
Q

product of enterokinase rxns is

A

trypsin

226
Q

most iron is transported in the blood via the plasma carrier:

A

transferrin

227
Q

organs most active in the synthesis of endogenous cholesterol are the liver and the _____

A

intestinal mucosa

228
Q

lactulose is a CHO that is

A

nonabsorbable laxative

229
Q

digested dietary protein is absorbed primarily in the

A

jejenum

230
Q

monosaccharides are transported across the placenta from the maternal circulation to the fetal circulation by the process of

A

facilitated diffusion

231
Q

if a bolus containing 600 mOsm/L enters the jejunum, the net direction of fluid movement in the intestinal tract will be:

A

from the circulation to the intestinal lumen

232
Q

excessive production of gas within the intestines may be caused by excessive colonic bacterial fermentation of unabsorbed

A

CHO

233
Q

a major intracellular antioxidant is the nutrient

A

glutathione

234
Q

a required prereq to the digestion of proteins is the HCl-dependent process called

A

denaturation

235
Q

the true digestibility of dietary fatty acids is

A

> 95%

CNS Exam (3 decks)

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