Digestion & Absorption - Ch 3

8/18/2019 Digestion & Absorption - Ch 3

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Chapter 3

DIGESTION &

ABSORPTION


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Digestion

• Digestion – The process of changing foodinto simpe components !hich the "od#can a"sor"

• Digesti$e tract or Gastrointestina tract%!here digestion & a"sorption tae pace

• 'o(th%)esophag(s%)stomach%)smaintestine%)arge intestine


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GI Tract Anatom#


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Digestion

• 'o(th – ingestion of food* che!ing+mastication, & s!ao!ing

-. Bo(s – portion of food s!ao!ed

at one time/. Sai$a % !ater0 sats0 en1#mes0

m(c(s secreted "# sai$ar# gands

to2 a. 'oisten food & aids s!ao!ing

". Begins car"oh#drate digestion


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Digestion

• Esophag(s – connects mo(th to stomach

-. Epigottis – coses air!a#

/. Bo(s mo$ed aong "# peristasis

3. 4ardiac sphincter – eeps food from"acing (p into esophag(s


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Digestion

• Stomach – coecting & ch(rning-. Gastric gands secrete2 gastric 5(ice

+!ater0 en1#mes0 h#drochoric acid, that

is most "acteria and "egins proteindigestion and m(c(s to protect ining

/. 4h#me – semi%i6(id mass of partia#

digested food3. P#oric sphincter – reg(ates passage

of ch#me into sma intestine


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Secretions of Digestion


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Digestion

•Sma Intestine – 3 segments2-. D(oden(m – opening from common "ie d(ct

secretes f(ids from2

a. 7i$er & Ga"adder – "ie em(sifies fat

". Pancreas – am#ase "rea do!n car"oh#drate0 sodi(m "icar"onate

ne(trai1es the acidic ch#me and ipase

/. 8e5(n(m

3. Ie(ma. Ieoceca $a$e – sphincter that reg(ates

passage of ch#me into arge intestine


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Digestion

• 7arge intestine +coon, % rea"sor"ing & eiminating

-. 9ermentation of (ndigested

resid(es "# "acteria occ(rs/. Terminates at rect(m0 !here !ater

some mineras are a"sor"ed

3. An(s – sphincter that contros defecation +e:cretion of fi"er

resid(e0 !astes and some !ater,


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The 9ina Stage


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Digestion

• '(sc(ar action heps to prope i6(efied

food thro(gh the G.I. tract "#2

-. Peristasis – m(sc(ar contractions

that p(sh contents for!ard

/. Segmentation – in!ard s6(ee1ing for

greater mi:ing of secretions3. Sphincter contractions


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Peristasis


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Segmentation


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Sphincter 4ontractions


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A"sorption & Transport

• End%prod(cts of digestion2

-. 4;O ))) 'onosaccharides

/. 9ats ))) G#cero < fatt# acids3. Proteins ))) Amino acids

=. >itamins0 mineras & !ater – no

digestion


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A"sorption


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• A"sorption occ(rs in the sma intestine

-. ?a of sma intestine co$ered

!ith -@@s of fods/. Each fod co$ered !ith -@@@s of

$ii

3. Each $ii contains -@@s of micro$ii


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The Sma Intestine >ia


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• A"sor"ed n(trients enter either the2

-. >asc(ar s#stem – !ater%so("e

n(trients +monosaccharides0 amino

acids0 !ater%so("e $itamins0

mineras0 !ater, enter the "ood $ia

the porta $ein for transport to thei$er


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/. 7#mph s#stem – fat%so("e n(trients

+ipids0 fat%so("e $itamins, enter here0

e$ent(a# entering the "ood near the

heart

3. Transport of ipids – since fats are inso("e in

!ater0 the# m(st "e pacaged for transport as

ipoproteins +trig#ceride0 phosphoipid0 protein0

choestero,


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A"sorption & Transport= "asic t#pes of ipoprotein2

-. 4h#omicrons – $er#0 $er# o! densit#

+C trig#ceride,* a"sor"ed from sma

intestine into #mph & circ(ated to ces

!here some of ipid materia is piced off

& remnants ret(rn to i$er

/. >7D7 – $er# o! densit# ipoprotein +@C trig#ceride,* made "# i$er &

tra$es to ces


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3. 7D7 – o! densit# ipoprotein +@C

choestero,* remains of >7D7* high

e$es increase ris of heart attac

=. ;D7 – high densit# ipoprotein +@C

protein,* remo$es choestero from "ood

for ret(rn to i$er* high e$es decrease

ris of heart attac


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pper GI Pro"ems

Dysphagia – diffic(t# s!ao!ing !ithtendenc# to choeaspirate

-. 9oods that are soft te:t(re & smooth

consistenc# critica to a$oid aspiration+i.e. p(dding consistenc# or p(reed,

/. Thicened i6(ids (sing commercia

thiceners are easier to s!ao!

3. T("e feeding into d(oden(m ma# "eindicated


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pper GI Pro"emsReflux esophagitis +Fheart"(rn, !hich often occ(rs d(e

to a hiata hernia and

Gastritis (infammation of stomach ining, and

Peptic Ulcers +erosions of the ining of stomach or

d(oden(m, re6(ire a bland diet to red(ce

gastric secretions and eiminate foods that

ca(se pain or discomfort

-. A$oid chocoate0 gariconions0 caffeine0

spic# & fatt# foods0 mint0 acoho

/. Sma meas !ith f(ids "et!een meas

3. Antacids & acid controers


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Gastroesophagea Ref(:


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Digesti$e Pro"ems

Delayed Gastric Emptying – ma# "e dea#ed

temporari# foo!ing s(rger# or chronica#

d(e to Dia"etes 'eit(s

-. 7o! fi"er0 o! fat speeds gastric empt#ing

& pre$ents "e1oars that ma# form a

"ocage

Constipation – pre$ent !ith a high fi"er diet and

treat "# drining pent# of f(ids inc(ding pr(ne 5(ice0 get reg(ar e:ercise & add a:ati$es

+h#drophiic cooids,0 as needed


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Digesti$e Pro"ems

Diarrhea/dehydration – treat (nder#ingca(se and repace f(ids & eectro#tes topre$ent deh#dration

-. 'id cases (se 5(ices0 sports drins0

caffeine%free sodas0 tea0 "roth0 orareh#dration form(as +e.g. Pedia#te,

Dierticular Disease

-. A$oid n(ts0 seeds0 h(s +e.g. ora0stra!"erries0 popcorn, !hich ma#

get trapped & ca(se di$ertic(itis


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Di$ertic(a in the 4oon


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'aa"sorption S#ndromes

Dumping !yndrome

4ar"oh#drate maa"sorption that occ(rs d(e to

remo$a of p#oric sphincter from partia

gastrectom# ca(sing osmotic diarrhea

-. S#mptoms inc(de !eaness0 di11iness0rapid heart"eat0 diarrhea0 a"domina pain

/. A$oid concentrated s!eets0 drin f(ids

"et!een meas0 eat sma0 fre6(ent meas


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"actose #ntolerance

4ar"oh#drate maa"sorption d(e to a ac of

the en1#me actase that spits actose into

g(cose < gaactose

-. Incidence assoc. !ith aging0 certain ethnicgro(ps0 and G.I. disease or s(rger#

/. S#mptoms inc(de cramping0 distention0

diarrhea after cons(ming prod(cts containing

mi or actose3. 7actose%Restricted Diet or en1#me ta"ets &

treated mi are aso a$aia"e


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$at %alabsorption – ca(sed "# disorders of thestomach0 intestine0 pancreas & i$er

-. Steatorrhea +fatt#0 oose0 foam#0 fo(

smeing stoos, !ith s("se6(ent oss of

energ#0 essentia fatt# acids0 and fat%so("e

$itamins

/. 7imit fat intae to 3%=@ gmsda#

3. S(ppementation !ith fat%so("e $itamins+!ater%misci"e forms a$aia"e,

=. En1#me repacement to aid digestion

& a"sorption


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Pancreatitis – infammation of the pancreas0

res(ting in impaired digestiona"sorption-. S#mptoms inc(de se$ere a"domina pain0

and na(sea & $omiting

/. Initia#0 N.P.O. +nothing "# mo(th, to rest

the pancreas (sing I.>. f(ids to maintain

f(id & eectro#te "aance

3. A$oiding acoho is imperati$e as diet

progresses=. 4hronic pancreatitis ma# ead madigestion

of fats0 chronic a"domina pain0 !eight oss

& dia"etes


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Cystic $ibrosis – hereditar# diseasecharacteri1ed "# thic m(c(s affecting man#"od# organs0 inc(ding (ngs & pancreas0 anda"norma# high eectro#te concentration in

s!eat-. Energ# & n(trient needs -/@%-@C of norma

/. 9at needed to meet high energ# needs so

en1#me repacements (sed to controsteatorrhea

3. 7i"era (se of f(ids & sat


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Celiac Disease +G(ten%sensiti$e enteropath#, –sensiti$it# to giadin0 part of the protein g(ten0fo(nd in !heat0 r#e0 "are# & oats

-. S#mptoms inc(de !eight oss0 diarrhea0

fatig(e0 anemia +iron0 foate0 >it. B-/,0

generai1ed maa"sorption0 "one disease

/. A$oiding foods containing g(ten re6(ires

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Digestion & Absorption - Ch 3

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