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Bacterial Flora in theBacterial Flora in the

ColonColon Numerous bacteria, especially colonNumerous bacteria, especially colon

bacilli, are present even normally inbacilli, are present even normally in

the absorbing colon.the absorbing colon.

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GIT IN INFANTSGIT IN INFANTS

BIRTH STERILE GITBIRTH STERILE GIT

BREASTFED INFANTSBREASTFED INFANTS

90% BIFIDOBACTERIA90% BIFIDOBACTERIA COWS MILK, SOLID FOODCOWS MILK, SOLID FOOD

BACTEROIDESBACTEROIDES

STREPSTREPENTERICSENTERICS

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GIT IN INFANTSGIT IN INFANTS

The gastrointestinal tract is sterile atThe gastrointestinal tract is sterile at

birth, but colonization typicallybirth, but colonization typically

begins within a few hours of birth,begins within a few hours of birth,

starting in the small intestine andstarting in the small intestine and

progressing caudally over a period ofprogressing caudally over a period of

several days. In most circumstances,several days. In most circumstances,

a "mature" microbial flora isa "mature" microbial flora isestablished by 3 to 4 weeks of ageestablished by 3 to 4 weeks of age

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Bacterial Flora in theBacterial Flora in the

ColonColon Bacteroides, bifidobacteria, lactics,Bacteroides, bifidobacteria, lactics,

enterics, enterococci, clostridia,enterics, enterococci, clostridia,

methanogens with bacteroides beingmethanogens with bacteroides being

the major variety (>700 species)the major variety (>700 species) Inhabited mostly by anaerobic bacteriaInhabited mostly by anaerobic bacteria

Other factors like POther factors like PHH also influencealso influence

inhabitanceinhabitance

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Microbial Populations in the Digestive Tract of NormalHumans

Stomach Jejunum Ileum Colon

Viable bacteria pergram

0 - 103 0 - 104 105 - 108 1010 - 1012

pH 3.0 6.0-7.0 7.5 6.8-7.3

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Bacterial Flora in theBacterial Flora in the

ColonColonSignificant functions areSignificant functions are

Synthesize VitaminsSynthesize Vitamins

Digests cellulose (incompletely)Digests cellulose (incompletely)

Prevents growth of pathogenic organismsPrevents growth of pathogenic organisms Contributes to gas formation (Flatus)Contributes to gas formation (Flatus)

Digests other undigested material (varies)Digests other undigested material (varies)

Symbiosis/mutualistic (not just commensal)Symbiosis/mutualistic (not just commensal)

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Bacterial production ofBacterial production of

VitaminsVitamins Vitamin K, BVitamin K, B

1212, thiamine, riboflavin, thiamine, riboflavin

and other B vitaminsand other B vitamins

Vitamin K synthesis for BloodVitamin K synthesis for Bloodcoagulation becomes importantcoagulation becomes important

during deficiencyduring deficiency

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Partial digestion ofPartial digestion of

CelluloseCellulose Degradation of cellulose by colonicDegradation of cellulose by colonic

bacteria varies, but generally it isbacteria varies, but generally it is

poorly fermented (doesnt digestpoorly fermented (doesnt digest

well)well)

Extra calories of nutritionExtra calories of nutrition

Significant in herbivorous animalsSignificant in herbivorous animals

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Prevents growth ofPrevents growth of

pathogenic organismspathogenic organisms

The bacteria found in the colon canThe bacteria found in the colon can

be grouped into two categoriesbe grouped into two categories

based on their effect on humansbased on their effect on humans

friendly or unfriendly bacteriafriendly or unfriendly bacteria

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Prevents growth ofPrevents growth of

pathogenic organismspathogenic organisms Unfriendly contribute to long-termUnfriendly contribute to long-term

illness and chronic degeneration ofillness and chronic degeneration of

the bodythe body

Friendly favorably alter theFriendly favorably alter the

intestinal flora balance,intestinal flora balance, inhibit theinhibit the

growth of harmful bacteriagrowth of harmful bacteria, promote, promote

good digestion, boost immunegood digestion, boost immunefunction, and increase resistance tofunction, and increase resistance to

infectioninfection

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Contributes to gasContributes to gas

formation (Flatus)formation (Flatus)

By-product of Bacterial metabolismBy-product of Bacterial metabolism

Carbon dioxide, methane, hydrogenCarbon dioxide, methane, hydrogen

sulfide, various other gasessulfide, various other gases

Contribute to PropulsionContribute to Propulsion

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Digests other undigestedDigests other undigested

materialmaterial Colonic bacteria primarily degradeColonic bacteria primarily degrade

carbohydrates, but they also usecarbohydrates, but they also use

some amino acids and proteins assome amino acids and proteins as

substrates necessary for thesubstrates necessary for theproduction of energy, and carbonproduction of energy, and carbon

atoms essential for bacterial growthatoms essential for bacterial growth

and maintenance.and maintenance.

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AppliedApplied

Rise in unfriendly bacteriaRise in unfriendly bacteria

Causes conditions likeCauses conditions like EnteritisEnteritis

(inflammation),(inflammation), Ulcerative colitisUlcerative colitis(inflamed and ulcerated)(inflamed and ulcerated)

Diarrhea resultsDiarrhea results

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AppliedApplied

Inhibition of Bacterial sustenanceInhibition of Bacterial sustenance

AntibioticsAntibiotics andand Poor intake of dietary fibrePoor intake of dietary fibreinhibit friendly species of bacteria as well asinhibit friendly species of bacteria as well as

the disease-causing bacteriathe disease-causing bacteria An individual who depends on absorption ofAn individual who depends on absorption of

vitamins formed by bacteria in the largevitamins formed by bacteria in the large

intestine may become vitamin deficient.intestine may become vitamin deficient.

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