Animal Phy Lec 3-7 Digestion

7/25/2019 Animal Phy Lec 3-7 Digestion

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Human Physiologyby Lauralee Sherwood 2007 Brooks/Cole-Thomson Learning

The Digestive System


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Engineers in Physiology

In the 1950s, a chemical engineering professor, Edward Merrill of MIT,was asked to help local doctors measure the viscosity of lung mucus

and human blood (a uids iscosit! is a measure of its thickness, orresistance to ow, when e"posed to stress#$

Edward Merrill


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In 1965, a variety of biocompatible plastics and composites were designed

by chemical engineers for use in prosthetic devicesand replacement valves,

arteries and veins.

The development of the widely used kidney dialysis machine provides a

good example of the lifesaving synergies that can result when biomedical

researchers and chemical engineers wor together.

Adam Heller

!hemical engineer, Adam Heller developed a rapid,

micro-analytical technique re"uiring a much smaller

sample of blood than previous sampling techni"ues#

$ust %&&n', which is about one(eighth of what amos"uito draws when it bites a human being.

)ngineers have built a continuous glucose monitorby

electrically wiring a glucose(reacting protein.



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Automatic insulin-injection pumps are computeri%eddeice, which draw on well&esta'lished micropumping

techniues deeloped '! chemical and mechanicalengineers, are t!picall! the si%e of a pager and can 'ecarried on a 'elt or shirt pocket$

)ork on microuidic deices has proided fertile groundfor innoatie colla'oration 'etween the chemical

engineering and 'iomedical communities$ Thesee"tremel! small anal!tical deices (often called *lab-on-a-chip+# are used to carr! out arious chemical,'iomedical and thermal reactions, measurements, andanal!ses with greater specicit!, speed, and relia'ilit!than conentional macro&scaled approaches$

-n organ-on-a-chip is a multi&channel .&/ micro uidic cell

culture chip that simulates theactiities, mechanics andph!siological response of entireorgans and organ s!stems$ Theconergence of la's&on&chips andcell 'iolog! has permitted the stud!

of human ph!siolog! in an organ&

specic conte"t, introducing a noel


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Engineering Digestion

ust tr!ing to take a drink or eat a meal in outer space can

'e er! challenging$ 2cientists and engineers who work for3-2- hae designed special deices to help astronauts eat&4Lunch in Outer Space+$

ae !ou heard of *astronaut ice cream or space icecream+6it was designed '! )hirlpool 7orporation undercontract to 3-2- for the -pollo missions$


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On the way to SUPERFOODS..


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The Human

Digestive System


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Digesi!e ra"# Coninuous $rom mouh o

anus# Consiss o$

%ouh &haryn'

(so)hagus Soma"h Small inesine

# Duodenum# *e+unum# ,leum

Large inesine# Cecum# !!en"i## Colon# e"um

.nus

.""essory digesi!e organs# Sali!ary glands# ('o"rine )an"reas# Biliary sysem

Li!er allbladder


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The Digestive Regimen


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Overview o$ the Digestive System


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&rimary $un"ion# Trans$er nuriens waer and ele"rolyes $rom

ingesed $ood ino body1s inernal en!ironmen

Four $unctions

# %oiliy

# Se"reion

# Digesion#.bsor)ion

O Di ti S t $ Ch i l


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The gus o$ )eo)le $un"ion like in"ustrial chemical

!lants

They are assemblies o$ ubes and anks in whi"h $oods are

hydroly3ed by en3yme-"aaly3ed rea"ions or $ermened by

microorganisms

aw maerials ener a one end wase maer is !oided a

he oher and !aluable )rodu"s are absra"ed on he way

. mill a he enran"e end redu"es he raw maerials osmall $ragmens enabling he rea"ions o )ro"eed $aser

Teeth is li%e a grin"ing mill and he digesi!e ube as a

"hain o$ "hemi"al rea"ors

Our Digestive System !er$orms Chemical

Engineering

E & i h $ E l i l R ' d i $ l $ i ll


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Eco&ot is shor $or Ecological Ro'ot and i re$ers o a "lass o$ energei"ally

auonomous robos ha "an remain sel$-susainable by "olle"ing heir energy $rom

maerial mosly wase maer in he en!ironmen


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Micro-robotic explorers, powered by microbial fuel

cells, could represent an efficient and reliable energy

source on a planet without human intervention


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Digestive Tract

4all has same general sru"ure hroughou lengh$rom eso)hagus o anus

5our ma+or issue layers

# (ucosa

,nnermos layer

# Su'mucosa

# (uscularis e#terna

# Serosa 6uer layer


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)ayers o$ Digestive Tract *all


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(ucosa

Lines luminal sur$a"e o$ digesi!e ra"

Highly $ol"e" sur$ace grealy in"reases absor)i!e area Three layers

# (ucous mem'rane Ser!es as !rotective sur$ace %odi$ied $or se"reion and absor)ion

Conains# E#ocrine glan" cells# se"ree digesi!e +ui"es# En"ocrine glan" cells# se"ree blood-borne gasroinesinal hormones# E!ithelial cells# s)e"iali3ed $or absorbing digesi!e nuriens

# )amina !ro!ria+--loose "onne"i!e issue ouses gu-asso"iaed lym)hoid issue 8,)T9

# ,m)oran in de$ense agains disease-"ausing inesinal ba"eria# (uscularis mucosa

S)arse layer o$ smooh mus"le: it eeps the mucosal surface andunderlying glands in a constant state of gentle agitation to expel contents ofglandular crypts and enhance contact between epithelium and the contents ofthe lumen.


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The Digestive E!ithelium

The oral "a!iy )haryn' and eso)hagus 8where me"hani"al sresses are mos se!ere9

are lined by a strati$ie" s-uamous e!ithelium whereas he soma"h he small

inesine and almos he enire lengh o$ he large inesine 8where absor)ion o""urs9

ha!e a sim!le columnar e!ithelium.

The li$e s)an o$ a y)i"al e)ihelial "ell !aries $rom two to three "ays in he eso)hagus

o u) o si# "ays in the large intestine The lining o$ he enire digesi!e ra" is

"oninuously renewed hrough he di!isions o$ e)ihelial sem "ells kee)ing )a"e wih

he rae o$ "ell desru"ion and loss a e)ihelial sur$a"es


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Su'mucosa

Thi"k layer o$ "onne"i!e issue

&ro!ides digesi!e ra" wih disensibiliy and elasi"iy

Conains larger blood and lym!h!essels

Conains ner!e nework known as su'+mucosal !le#us

(eissners Ple#us/;inner!aes he mu"osal e)ihelial

layer and glands---!ara+sym!athetic stimulation


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(uscularis E#terna

%a+or smooh mus"le "oa o$ digesi!e ube

,n mos areas "onsiss o$ wo layers# Circular layer

,nner layer

Conra"ion de"reases diameer o$ lumen

# )ongitu"inal layer 6uer layer

Conra"ion shorens he ube

Conra"ile a"i!iy )rodu"es )ro)ulsi!e and mi'ing

mo!emens (yenteric0uer'ach1s !le#us

# Lies beween he wo mus"le layers: provides motorinnervations to both layers of the tunica muscularis, havingboth parasympathetic and sympathetic input.


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Serosa

Se"rees serous $lui"

# )u'ricates an" !revents $riction beween

digesi!e organs and surrounding !is"era

Coninuous wih mesenery hroughou mu"h o$ he

ra"

#.a"hmen )ro!ides relai!e $i'aion

# Su))ors digesi!e organs in )ro)er )la"e while

allowing hem $reedom $or mi'ing and )ro)ulsi!e

mo!emens


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Regulation o$ Digestive System

Digesi!e moiliy and se"reion are regulaed by

#.uonomous smooh mus"le $un"ion 8PacesetterCells9: slow wa!e 8B(9

# 2ntrinsicner!e )le'uses

# E#trinsicner!es

# asroinesinal hormones


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Pacesetter cells Ca3al/+generae slow wa!e )oenials he

,1s basi" ele"ri"al rhyhm 8B(9 wa!elike $lu"uaions inmembrane )oenial ransmied hroughou smooh mus"le !ia

ga) +un"ions

Threshold is rea"hed by he e$$e" o$ !arious me"hani"al

neural and hormonal $a"ors in , ra"

These smooh mus"le "ells undergo s)onaneous "onra"ion

ha riggers a wa!e o$ "onra"ion ha s)reads hrough he

enire mus"ular shee &a"eseer "ells are lo"aed in he

muscularis mucosae an" muscularis e#terna he layers o$whi"h surround he lumen o$ he digesi!e ra" The "oordinaed

"onra"ions o$ he mus"ularis e'erna )lay a !ial role in he

mo!emen o$ maerials along he ra" hrough )erisalsis and in

me"hani"al )ro"essing hrough segmenaion

&a"eseer Cells

& i b


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&oins o remember

&a"eseer Cells do no iniiae an a"ion )oenial


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*hy an anti+cholinergic "rug li%e4 anti+

histamines cause consti!ation5

They are also !rescri'e" $or "e!ression 6 slee!

"isor"ers an" gastro intestinal cram!s


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2n ,2 tract Parasym!athetic 7S !lays

ma3or role.Sym!athetic 7S.actsonly un"er e#treme stress


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Rest an" Digest


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Summary o$ Pathways Controlling Digestive

System ctivities

( tilit


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(otility

%oiliy

# %us"ular "onra"ions ha mi' and mo!e $orward

he "onens o$ he digesi!e ra"

# Two y)es o$ digesi!e moiliy

Pro!ulsive movements# &ush "onens $orward hrough he digesi!e ra"

(i#ing movements

# Ser!e wo $un"ions

< %i'ing $ood wih digesi!e +ui"es )romoes digesion o$

$oods

< 5a"iliaes absor)ion by e')osing all )ars o$ inesinal

"onens o absorbing sur$a"es o$ digesi!e ra"

% ili & i l i


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%oiliy--&erisalsis

The )aerns o$ , "onra"ion as a whole "an be

di!ided ino Peristalsis an" Segementation

&erisalsis o""urs as a series o$ !eristaltic wave

cycles in disin" )hases saring wih rela'aion

$ollowed by an in"reasing le!el o$ a"i!iy o a )eak

le!el o$ )erisali" a"i!iy lasing $or =#>= minues

This "y"le re)eas e!ery 8.9:; hours bu is

inerru)ed by $ood ingesion

The role o$ his )ro"ess is likely o clean e#cess

'acteria an" $oo" $rom the "igestive system

&erisalsis o""urs during and shorly a$er a meal

The "onra"ions o""ur in wa!e )aerns ra!eling

down shor lenghs o$ he , ra" $rom one se"ion o

he ne' The contractions occur "irectly 'ehin"

the 'olus o$ $oo" ha is in he sysem $or"ing i

oward he anus ino he ne' rela'ed se"ion o$

smooh mus"le

% ili S i


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%oiliy--Segmenaion

Segmenaion also o""urs during

and shorly a$er a meal wihin shorlenghs in segmened or random

)aerns along he inesine This

!rocess is carrie" out 'y

longitu"inal muscles rela'ing while

"ir"ular mus"les "onra" a

alernaing se"ions hereby mi'ing

he $ood This mi#ing allows $oo"

an" "igestive en


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This is the same %in" o$ muscular

movement that allows worms to move


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&erisalsis and Segmenaion


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&erisalsis and Segmenaion

# iniiaed by !acema%er cells in small inesine

whi"h )rodu"e 'asic electrical rhythm &ER/# Cir"ular smooh mus"le res)onsi!eness is

in$luen"ed by disension o$ inesine gastrin ande'rinsi" ner!e a"i!iy

# 5un"ions %i'ing "hyme wih digesi!e +ui"es se"reed ino small

inesine lumen

(')osing all "hyme o absor)i!e sur$a"es o$ smallinesine mu"osa

%igraing moiliy "om)le'

# Sweeps intestines clean between meals

%oiliy Diseased Condiion


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%oiliy?Diseased Condiion

,n normal digesion $ood "onen is )ro)elled hrough he digesi!e

ra" by rhyhmi" and coor"inate" contractions or !ro!ulsionscalle" !eristalsis

4hen someone su$$ers $rom a digesi!e moiliy disorder )erisalsis

be"omes im)aired resuling in slow "onra"ions ra)id "onra"ions or

ha!ing a "ombinaion o$ boh slow and $as "onra"ions ,n some

"ases )erisalsis may be oally absen

Some )eo)le a$$e"ed by moiliy disorders may be underweigh

Digesi!e moiliy diseases is generally se"ondary when he moiliy)roblem o""urs as a resul o$ a "isease or me"ical con"ition

('am)les o$ se"ondary "auses in"lude "ia'etes4 Par%inson=s

Disease4 en"ocrine "isor"ers4 neurological "isor"ers4 la#ative

a'use4 an" a'"ominal surgery


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(uscles contract in waves to move the $oo" "own the

oeso!hagus. This means that $oo" woul" get to a

!erson=s stomach4 even i$ they were stan"ing on theirhea"


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hat happens if a large chunk of food

gets stuck in esophagus

*hy "oes your stomach Rum'le0,rowl


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*hy "oes your stomach Rum'le0,rowl


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Peo!le who eat on very regular sche"ules may 'e more

susce!ti'le to this RU(&)27,. For e#am!le i$ the

stomach receives $oo" at noon every "ay4 then the 'o"ywill e#!ect $oo" at noon4 whether $oo" is !resent or not.

(a%e sure you eat a HE)TH> 'rea%$ast so that your

'o"y "oesn=t run low on $uel energy/ 'e$ore lunchtime.


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To"ay1s Scenario


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To"ay s Scenario


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2t ta%es your mouth4 eso!hagus4 stomach4small intestine4 large intestine4 gall'la""er4

!ancreas an" liver 3ust to "igest a glass o$

mil%.


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Sali!a


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Sali!a

Saliva* +roduced largely by three ma$or pairs of salivary glands

* !omposition

99.5- /0 &.5- electrolytes and protein amylase, mucus, lyso2yme3

* 4unctions

alivary amylase begins digestion of carbohydrates

4acilitates swallowing by moistening food

ucus provides lubrication and Antibacterial action

alivary ;lands


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alivary glands % pairs3 ( parotid,

sublingual, and submandibular7produce saliva

timulated by thought of food or

ingested food

There is constant low level of

secretion

8asal ate &.5ml:min

The rate depends on "uantity of

food.

alivary ;lands

Control of alivary ecretion


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Control of alivary ecretion

Control o$ Salivary Secretion


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Control o$ Salivary Secretion

Salivary &u$$ering


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Salivary &u$$ering

Sali!a "onains !hos!hate whi"h is "a)able o$ bu$$ering he

)

Phos!hate is a goo" 'u$$er an" !hos!hate salts are widely

used in s"ien"e o )re)are bu$$er soluion owe!er alhough we

hink o$ sali!a as "onaining a lo o$ )hos)hae i +us does no

"onain enough o allow i o be really e$$e"i!e in vivo.

This lea!es us wih bi"arbonae whi"h is o$en re$erred o as he

ma+or bu$$er o$ sali!a ,n mouh bi"arbonae a"s mainly o

neurali3e a"id

The normal4 resting4 !H o$ the mouth "oes not $all much

'elow a'out !H ?.@ an" the reason $or this is the

'icar'onate.


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Cha)er >@ The Digesi!e Sysem



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Cha)er >@ The Digesi!e Sysem


Stomach


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Stomach

Three main $un"ions# Store ingeste" $oo" unil i "an be em)ied ino small inesine# Se"rees hy"rochloric aci" HCl/ and en


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Has $oo" "igestion starte" 'e$ore

reaching stomach5

Heart'urn


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Heart'urn

,astric (otility


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,astric (otility

5our as)e"s

# 5illing ,n!ol!es Rece!tive Rela#ation

# (nhan"es soma"h1s abiliy o a""ommodae he e'ra!olume o$ $ood wih lile rise in soma"h )ressure

# Triggered by a" o$ eaing

# %ediaed by Aagus nerve

# Sorage Ta%es !lace in 'o"y0$un"us o$ stomach 555

%i'ing

Takes )la"e in anrum o$ soma"h# Em!tying

)argely controlle" 'y $actors in "uo"enum

,astric Em!tying an" (i#ing as a Result o$


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ntral Peristaltic Contractions

,astric Em!tying


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,astric Em!tying

5a"ors in soma"h# mount o$ chyme in stomach is main $actor that in$luences

strength o$ contraction

5a"ors in duodenum# Fat

5a digesion and absor)ion akes )la"e only wihin lumen o$ smallinesine

*hen $at is alrea"y in "uo"enum $urher gastric em!tying o$addiional $ay soma"h "onens is !revente"

# ci" Un+neutrali


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,ast c !ty g

5a"ors rigger eiher

# 7eural res!onse %ediaed hrough boh inrinsi" ner!e )le'uses 8shor re$le'9

and auonomi" ner!es 8long re$le'9

Colle"i!ely "alled enterogastric re$le#

.ddiional $a"ors ha in$luen"e gasri" moiliy

# Emotions

Sa"ness an" $ear# end o de"rease moiliy nger an" aggression# end o in"rease moiliy

# 2ntense !ain# ends o inhibi moiliy

,astric Secretions


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Two disin" areas o$ gasri" mu"osa ha se"ree gasri" +ui"e

#O#yntic mucosa Lines body and $undus

# Pyloric glan" area P,/

Lines he anrum

asri" glands a base o$ gasri" )is-

Three y)es o$ gasri" e'o"rine se"reory "ells# (ucous cells

Line gasri" )is and enran"e o$ glands

Se"ree hin waery mu"us

# Chie$ cells

Se"ree en3yme )re"ursor Pe!sinogen 555/

# Parietal o#yntic/ cells

Se"rees HCl5555

Colle"i!ely hey make ,astric Buice

HCl an" its Role


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Functions o$ HCl#."i!aes !e!sinogen to active en


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Hormonal Regulation


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Aagussimulaion and ctsimulaes

)arieal and "hie$ "ells

"ells are simulaed by !agalsimulaion hrough gastrin+releasing

!e!ti"e his "auses he "ells o

se"ree gasrin whi"h in urn no only

dire"ly simulaes )arieal "ells bu

hrough EC) cells o release

histamine

These "ells are simulaed by he

hormone gastrin

isamine and gasrin a"

synergisi"ally as he mos im)oran

simulaors o$ CL se"reion $rom

)arieal "ells and simulaors o$

se"reion o$ !e!sinogen $rom chie$

cells.


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The stomach is exposed to the harshest conditions in the digestive tract

!o keep from digesting itself, the stomach has a mucosal barrierwiths ma$or biochemical factory

Importance to digestive system * secretion of bile salts

)iver


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&ile# ."i!ely se"reed by li!er and a"i!ely di!ered o gallbladder beween meals# Sored and "on"enraed in gallbladder# Consiss o$

&ile salts Cholesterol Le"ihin Bilirubin

# .$er meal bile eners duodenum

&ile salts# Deri!ai!es o$ "holeserol# Con!er large $a globules ino a liuid emulsion# .$er )ari"i)aion in $a digesion and absor)ion mos are reabsorbed ino he blood

Pancreatic )i!ases


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Digestion an" 'sor!tion o$ Fats


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*ho are the $erries in your $at

"igestion555


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*here are the chylomicrons $orme"

insi"e the cells5

*hy cant they enter the 'loo" vessels5

*hy "o we $eel slee!y a$ter eating


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How "oes the 'o"y a'sor' vitamins5


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The small intestine is where vitamin absorption happens along with most other

types of absorption3. ?ater(soluble vitamins, such as vitamin !, have @activetransports@ for absorption (( molecules that pic them up in the small intestine,

in a section called the#e#unum&

The 8 vitamins are also water(soluble and need to be replenished every day,

although their absorption wors a bit differently. TheyAre bound to proteins andtherefore re"uire a protein breadown triggered by stomach acids. =bsorption of

most of the 8 vitamins happens further down in the small intestine, in the ileum.

!he other type of vitamin, the fat-soluble ones such as A, %, " and (, need

to dissolve in fat before they can make it into the body. The process re"uiresfat(digesting bile acids that come from the liver and live in the small intestine.

?hen the bile acids brea down the fat the vitamins are dissolved in, the

vitamins move with the fat through the intestinal wall, into the body, and finally

end up in the liver and in body fat, where theyAre stored until theyAre needed

much lie fat3.


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Try!sin "lea!es )e)ide bonds on he "arbo'yl side o$ basi" amino a"ids 8lysine and arginine9

Chymotry!sin "lea!es )e)ide bonds on he "arbo'yl side o$ aromai" amino a"ids 8ryosine)henylalanine and ry)o)han9

Car'o#y!e!ti"ases 3in"-"onaining meallo-en3ymes ha remo!e single amino a"ids $rom

he "arbo'yl-erminal ends o$ )roeins and )e)ides

Small 2ntestine


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Cha)er >@ The Digesi!e SysemHuman Physiologyby Lauralee Sherwood 2007 Brooks/Cole-Thomson Learning

Sie where mos digesion and absor)ion 8E=F9

ake )la"e Three segmens

# Duodenum

# *e+unum

# ,leum

%oiliy in"ludes

# Segmenaion

# %igraing moiliy "om)le'

Large ,nesine


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&rimarily a drying and sorage organ

Consiss o$# Colon

# Cecum

# !!en"i#

# Rectum Conens re"ei!ed $rom small inesine "onsiss o$

indigesible $ood residues unabsorbed biliary"om)onens and remaining $luid

Colon# E#tracts more water an" salt $rom contents

# 5e"es # wha remains o be eliminaed

Large ,nesine


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Cha)er >@ The Digesi!e SysemHuman Physiologyby Lauralee Sherwood 2007 Brooks/Cole-Thomson Learning

Large ,nesine


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(ass movements

# %assi!e "onra"ions# %o!es "oloni" "onens ino disal )ar o$ large inesine ,astrocolic re$le#

# %ediaed $rom soma"h o "olon by gasrin and byauonomi" ner!es

# %os e!iden a$er $irs meal o$ he day# 6$en $ollowed by urge o de$e"ae De$ecation re$le#

# ,niiaed when sre"h re"e)ors in re"al wall are simulaedby disension

# Causes inernal anal s)hin"er o rela' and re"um andsigmoid "olon o "onra" more !igorously# ,$ e'ernal anal s)hin"er 8skeleal mus"le under !olunary

"onrol9 is also rela'ed de$e"aion o""urs

Animal Phy Lec 3-7 Digestion

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